Editing Drawings

Manifold provides rapid and efficient editing of drawings, either in a drawing window or as a drawing layer in a map window.   Manifold editing tools allow us to modify existing features in drawings, like changing the shape of areas or lines, or to create new features.    When we modify or create we can alter or specify the attributes that is, the field values of objects, or we can alter or specify the geometry of those objects, that is, the coordinates of the vertices that define them, or we can edit both attributes and geometry.

Drawings can be edited interactively, using point-and-click mouse moves to do things like reshape areas, or with commands to edit many features at once, for example, using the Transform pane to convert all selected area objects into lines, or using the Merge Drawings command to combine multiple drawings into a single drawing.  Drawings can also be edited using queries or scripts.  

This topic describes interactive editing using mouse moves and keyboard, showing how to create new objects in drawings and how to modify existing objects. To change the appearance of drawings, by changing colors and symbology, see the Style pane for drawings.

Drawings and measurement use exactly the same moves for drawing lines or paths.   See the Measurements topic for step by step examples applicable to drawing and editing features in drawings.

Index Required - A drawing's table must have a key field and index on that field for the drawing to be editable.  When Manifold creates or imports drawings it automatically adds the necessary key field and index, so we do not normally need to think about this.  However, if somebody has manually deleted the necessary index, we will not be able to edit the drawing. To add an index to a table that does not have an index, see the Add an Index to a Table topic.

Create New Features

We edit drawings to create new areas, lines, and points by choosing the Create Area, Create Line, and Create Point options within the cursor mode button in the main toolbar.  We can also choose the cursor mode from the main menu using the View - Mode command.

 Choose Create Area, and then click where we would like vertices to appear, using snap modes to guide clicks if we like.  

Keyboard shortcuts for different snap modes work during clicking and dragging, so while creating new objects we can switch between no snapping or snaps to coordinates, bearings, etc.  When done, we right-click and choose Save Changes.

In the illustrations above we create a new, red area adjacent to an existing area.  When creating new areas, we can toggle cursor snapping on and off as desired, to snap the cursor to existing vertices.  That allows us to create the new area exactly adjacent to the existing area.   Another way to create the same area, and to automatically clip the new area to the boundaries of an existing, adjacent area, is to use the Clip editing command.

The Info pane automatically pops open when we add a new object, showing fields for that object.  That allows us to enter field values, or attributes, for the object's record in the drawing's table as part of creating that object.  

Shortcut: Press Shift-Space to exit an object creation mode and to get back to Default navigation mode.

Alt-click to Modify Existing Features

We can edit drawings to modify existing areas, lines and points, in two ways, based on the tab chosen in the Info pane.

• Values - Edit attributes - This shows the values for attributes in the Info pane and allows us to make changes.

• Coordinates -  Edit geometry - This shows the coordinates for the object  in the Info pane and allows us to make changes either in the map or in the coordinates list.

Alt-clicking an object puts it into Values mode.   Clicking any coordinate handle or segment, or choosing the Coordinates tab, puts it into Coordinates mode (same as Move Coordinates mode in context menus).

 With the cursor in Default navigation mode, Alt-click an object in the active layer to pick it for editing: that launches the Info pane and allows us to view and edit attributes.  

Shift-Alt-click to pick an object in any visible layer, automatically making active the layer that contains the picked object.  If objects in different layers overlap, the highest layer wins.  

After picking an object, we can immediately edit attribute values for that object in the Info pane.  To edit the shape of the object, click on any vertex or segment in the object to put it into Move Coordinates editing mode.   We can then move the clicked vertex by dragging it, or we can move the entire object by Shift-dragging the clicked vertex.    Keyboard shortcuts for different snap modes work during dragging, so while editing objects we can switch between no snapping or snaps to coordinates, bearings, etc.,  in the middle of editing motions.

We apply edits by pressing Update Record in the Info pane, or by pressing Ctrl-Enter, or by right-clicking anywhere and choosing Save Changes.   We can abandon edits, not making any changes, by right-clicking anywhere and choosing Undo Changes, or by switching to another layer, or by choosing a different cursor mode, or by pressing Ctrl-Backspace.   Esc exits editing mode if there are no uncommitted changes.  

We can Ctrl-click several vertices to select them, which allows us to move all selected vertices together.  

In the illustrations above we have Alt-clicked the area to be edited.  We then Clicked one of the vertices to switch into Coordinates mode.  Next, we Ctrl-clicked four of the vertices on one side of the area to select them. Selected vertices are shown in darker blue color when editing.  We can also select edit handles by Ctrl-dragging a selection box around the handles we want to select.  

Dragging any of the selected areas moves all of them.    If we want to move the entire object, Shift-dragging the big edit handle will move the entire object.   Press Ctrl-Enter to commit the changes, or right-click and choose Save Changes from the context menu.

If we do not want a layer to be editable in a map, we can use the Layers pane to disallow picks in that layer.

Alt-Click to View and Edit Attributes

Use the Info pane to view and edit attributes.   The Info pane automatically pops open when we pick an object with an Alt-click.  That allows us to edit the field values, or attributes, for the object's record in the drawing's table.  We can do that for existing objects or we can do that on the fly when creating new objects.  

To unpick a picked object, press Esc if there are no uncommitted changes, or Alt-click on a blank part of the map (not on some other object), or Ctrl-Backspace.

Alt-click an object to pick it for editing and to pop open the Values tab of the Info pane.

We can then edit field values for that object.  

Edits are shown with provisional blue background until we commit them by pressing the Update Record button.  That allows us to change more than one value at the same time, which may be required if there are constraints on the data table.

View and Edit Geometry

For safety, editing the geometry of an existing object is a two-step process: We first Alt-click the object to pick it for Values mode, viewing and editing attributes, and then we switch into Coordinates mode to edit the shape of the object.  

There are four ways quickly to switch the object into Move Coordinates mode, the default editing mode:

• Click any vertex in the object.

• Click any segment in the object.

• Click on the Coordinates tab in the Info pane.

• Right-click anywhere in the map and choose Edit Coordinates.

Most users will click a vertex or segment in the object.  The clicked vertex will enlarge to show it is the active vertex for editing.   In Move Coordinates mode we can edit an object either in the drawing or in the Coordinates tab of the Info pane.   We can go back and forth between the drawing window and the Coordinates tab, using whichever interface is convenient whenever we like.

In the drawing, drag the active vertex to a new location, or use any of the editing commands available in the context menu by right-clicking in the drawing.

In the illustrations above we have Alt-clicked the area and then we have clicked the vertex to be moved.  We drag it to a new position, and then we press Ctrl-Enter to commit the edit.  If we prefer we can right-click and choose Save Changes from the context menu.    We do not have to update every change: we can make many changes and the system will show the edited object in blue preview outline color.  We can go back and make corrections or changes to our edits.  When we like what we see, we can commit changes, or abandon them with no changes to the object.

We commit edits by pressing Update Record in the Info pane, or by pressing Ctrl-Enter, or by right-clicking anywhere and choosing Save Changes.   We can abandon edits, not making any changes, by right-clicking anywhere and choosing Undo Changes, or by switching to another layer, or by choosing a different cursor mode, or by pressing Ctrl-Backspace.   Esc exits editing mode if there are no uncommitted changes.  

Coordinates Tab

The Coordinates tab of the Info pane lists in order all coordinates, that is, vertices, that define an object.  

In the Coordinates tab, we can double-click into a coordinate cell to manually edit the coordinates for that vertex.   We can select multiple vertices either in the drawing window or in the Coordinates list, and then any edit we make to any one of them in the Coordinates list will apply to all selected rows.  

For example, in the illustrations below we select two vertices in the Coordinates list.  

Then we press Delete to delete them.

When we delete the coordinates in the list, the object snaps into the new shape, shown in provisional, blue color over the current shape.

Press the Update Record button or Ctrl-Enter to apply the changes.  

Press Ctrl-Backspace to abandon the changes, or right-click and choose Undo Changes.   See the Info Pane topic for detailed instructions on editing objects using the Info pane.

To quickly exit editing mode, either press the Values tab or click some distance away from the object.  That will shift from editing mode showing the Coordinates tab list to the Values tab list showing attributes.

Snap Modes

Snapping jumps the mouse cursor directly to a desired location, like a point or the end of a line, when the mouse cursor moves near that location.  That makes it easy to exactly click a desired location just by moving the mouse cursor approximately nearby.   Snap Modes control snapping and turn it on and off.  We can also use snap modes to constrain mouse cursor motion to specified grid locations or to bearings, such as only horizontal or vertical motions.  

 Snap mode is indicated with a blue box cursor that snaps to locations allowed by the snap mode.  Snapping is off when we first launch a new Manifold session, and then stays off or on depending on how we last toggled it in that Manifold session.  Snapping status is a common setting between the path tool and editing commands, so if in the path tool or while editing we have last turned snapping off, or we have changed the snapping mode, it will stay off or stay in the new mode until we turn snapping back on or change to a different mode.

When in edit mode, the Spacebar is a keyboard shortcut that toggles snapping on and off.   We also can toggle snapping on and off when in edit mode by right-clicking into the drawing and choosing Snap from the context menu.  The right-click context menu also allows us to switch snap modes, from the default snapping to nearby vertices to other snap modes.    See the Snap Modes topic for full information, keyboard shortcuts, and examples.  

 By default, snapping works only with objects in the active layer.  If we uncheck the Snap to Active Layer Only choice in the right-click context menu, then snapping will work for all visible layers which have snapping enabled in the Layers pane.

Snapping might be confusing for beginners when first learning how to create lines and other objects.  If the mouse cursor is jumping to objects and vertices nearby instead of allowing us to click where we want, right-click and see in the context menu if snapping is on.   If snapping is on, turn it off if snapping is not desired.   When editing or using the path tool, we can toggle snapping off and on by pressing the Spacebar.

Snap parameters used in some Snap Modes can be set in the Snap Parameters dialog, which we can call from the cursor mode menu or by launching View - Mode - Snap Parameters from the main menu.

Creating New Points, Lines and Areas

Open the drawing in a drawing window or as a layer in a map.  The cursor mode button in the main toolbar switches the mouse cursor between default navigation, creating objects, or creating paths for measurement or editing.

The drop-down menu on the mode button lets us choose a different mode.

To create new objects in a drawing, choose Create Area, Create Line, or Create Point mode and then click away to create the object desired.  If in the middle of creating a complex line or area we realize that some earlier clicks were off, we can go back and adjust them, and then continue with more clicks where we left off.  When finished, right-click and choose Save Changes.

If we choose Create Point the mouse cursor user interface switches from Default navigation mode into Create Point mode.

The mode button always shows what mode applies for that window.   Hovering the mouse over the mode button will show a tooltip.

Different windows can have different modes, with one window being in Create Line mode while another window stays in Navigation mode.  As we switch between windows the mode button will automatically switch to show the mode for that window.

Shortcuts: When in a Create... mode, press Shift-Space to get back to Default navigation mode.  When not actively editing, for example, when we have just saved changes or have just undone changes, Alt-clicking to pick another object or Ctrl-clicking to select another object, will also end Create... mode.  That shortcut allows jumping directly from some Create... mode or Draw Path mode straight into work on the next object of interest.

Attributes

When creating points, lines, or areas, with the first click the Info pane will pop open to the Values tab, allowing us to enter attribute values for the new object.  At any time we can move the mouse from the drawing window to the Info pane, and then double-click into any of the attribute field cells to enter a value we want.  Enter to apply the value, just like editing a table.

Copy, Cut, Paste

We can also insert points, lines, and areas by pasting objects that have been copied or cut from another drawing window or drawing layer in a map window, or from a table that has a geometry field.  Pasting objects between drawings or tables that have different field names will launch the Paste dialog to allow mapping contents from one field name to a different field name.

Pasting with Ctrl-V automatically matches field names from the source drawing or table to the destination drawing or table, automatically iterating mfd_id values to avoid collisions between pasted records from the source table that originally had the same mfd_id value as existing records do in the destination table.    If field names do not match, the Paste dialog will automatically be launched.

Pasting with Shift-Ctrl-V calls up the Paste dialog even if all field names match.   In the Paste dialog,  click into a cell in the right-hand column and in the pull down menu choose ignore Field to paste objects with a NULL value in that field.  Choosing ignore Field for the special mfd_id field will automatically create new, unique mfd_id values, avoiding any collisions in mfd_id values with existing records.  The pull down menu will also allow us to map different source fields into destination fields.

We can also create a new table in the Project pane by pasting records or objects copied or cut from a table, a drawing or a drawing layer in a map window.  Copying records from a table or objects from a drawing and then pasting into the Project pane creates a table that is the same name, with an added number to iterate the name, as the source table or drawing's table.

See the Copy and Paste between Drawings or Tables topic for examples.

Keyboard Shortcuts

Create Points

Shortcut: Press Shift-P to launch Create Point mode.

To add new points to a drawing:

1. Click the cursor mode button and choose Create Point.  The button will show Create Point mode.

2. Click on locations in the drawing where a point is to be created.  Manifold will draw a blue preview square at each location.

3. When all desired points have been clicked, to commit changes right-click anywhere in the drawing and choose Save Changes from the context menu, or press the Add Record button in the Info pane Coordinates tab.  

4. To abandon changes, right-click and choose Undo Changes, or switch to a different layer.

We can use keyboard shortcuts to save changes or to undo changes.  Ctrl-Enter to save changes, and Ctrl-Backspace to undo changes.

To create a multipoint, either press Shift-Ctrl-Enter or press the Shift key when clicking on the Save Changes context menu choice.   See the Notes below on multipoints.

Attributes - When creating many points at once, whatever field values we enter into the Info pane Values tab will be used for all the points so created.   If we want to create points with different field values, then after clicking once to create a point, we enter the attribute values desired and then Save Changes or press Ctrl-Enter to create that point.  That allows us to create points with different attribute values for each point.

Create Lines

See the Editing Drawings - Create Lines with Curves video for a live action example.

Shortcut: Press Shift-L to launch Create Line mode.

To add a new line to a drawing:

1. Click the cursor mode button and choose Create Line.  The button will show Create Line mode.

2. Click on a location in the drawing to start the line and then click on subsequent locations to indicate where each next coordinate defining the line is to be placed. Manifold will draw a blue preview square at each coordinate with a blue preview line between clicked locations and also extending from the last clicked location to the current cursor position.

3. When creating a line, we can go back and adjust clicked coordinates: Press the M key (shortcut to Move Coordinates mode) or right-click and choose Move Coordinates from the context menu. Click the coordinate to be moved, and then drag it as desired to a new location.  To continue the line, right-click and choose Continue Last Branch.  

4. After clicking the last coordinate for the line, to commit changes right-click anywhere in the drawing and choose Save Changes from the context menu, or press the Add Record button in the Info pane Coordinates tab.  

5. To abandon changes, right-click and choose Undo Changes, or switch to a different layer.

We can use keyboard shortcuts to save changes or to undo changes.  Ctrl-Enter to save changes, and Ctrl-Backspace to undo changes.

To add a new, branched line to a drawing:

1. Click the cursor mode button and choose Create Line.  The button will show Create Line mode.

2. Click on a location in the drawing to start the first branch of the line and then click on subsequent locations to indicate where each next coordinate defining that branch is to be placed. Manifold will draw a blue preview square at each coordinate with a blue preview line between clicked locations and also extending from the last clicked location to the current cursor position. With the first click the Info pane Coordinates tab will pop open in the Info pane.

3. For the last coordinate of the branch, shift-click to add that last coordinate.  An inverted T symbol in the right margin of the coordinates list marks the end coordinate of a branch.

4. With the next click a new branch will be started at the clicked location.   Click on subsequent locations to indicate where each next coordinate for that branch should be placed.  

5. When creating a branch, we can go back and adjust clicked coordinates: Press the M key (shortcut to Move Coordinates mode) or right-click and choose Move Coordinates from the context menu. Click the coordinate to be moved, and then drag it as desired to a new location.  To continue the branch, right-click and choose Continue Last Branch.  

6. After clicking the last coordinate for the last branch, to commit changes right-click anywhere in the drawing and choose Save Changes from the context menu, or press the Add Record button in the Info pane Coordinates tab.  

7. To abandon changes, right-click and choose Undo Changes, or switch to a different layer.  

We can use keyboard shortcuts to save changes or to undo changes.  Ctrl-Enter to save changes, and Ctrl-Backspace to undo changes.

Measurements and editing uses similar commands and mouse moves to draw path lines that allow us to measure distances and bearings, or to edit objects.

Create Areas

See the Editing Drawings - Create Areas  video for a live action example.

Shortcut: Press Shift-A to launch Create Area mode.

To add a new area to a drawing:

1. Click the cursor mode button and choose Create Area.  The button will show Create Area mode.

2. Click on a location in the drawing to start the area and then click on subsequent locations to indicate where each next coordinate defining the area is to be placed. Manifold will draw a blue preview square at each coordinate with a blue preview line between clicked locations and also extending from the first location to the current cursor position.

3. When creating an area, we can go back and adjust clicked coordinates: Press the M key (shortcut to Move Coordinates mode) or right-click and choose Move Coordinates from the context menu. Click the coordinate to be moved, and then drag it as desired to a new location.  To continue the area, right-click and choose Continue Last Branch.  

4. After clicking the last coordinate for the area, to commit changes right-click anywhere in the drawing and choose Save Changes from the context menu, or press the Add Record button in the Info pane Coordinates tab.  

5. To abandon changes, right-click and choose Undo Changes, or switch to a different layer.  

We can use keyboard shortcuts to save changes or to undo changes.  Ctrl-Enter to save changes, and Ctrl-Backspace to undo changes.

To add a new, branched area to a drawing:

1. Click the cursor mode button and choose Create Area.  The button will show Create Area mode.

2. Click on a location in the drawing to start the first branch of the area and then click on subsequent locations to indicate where each next coordinate defining that branch is to be placed. Manifold will draw a blue preview square at each coordinate with a blue preview line between clicked locations and also extending from the first clicked location of the branch to the current cursor position.  With the first click the Info pane Coordinates tab will pop open in the Info pane.

3. For the last coordinate of the branch, shift-click to add that last coordinate.   An inverted T symbol in the right margin of the coordinates list marks the end coordinate of a branch.

4. With the next click a new branch will be started at the clicked location.

5. Starting a new branch within an area begins creating a hole in that area.  Starting a new branch outside of an area begins creating an island.

6. Click on subsequent locations to indicate where each next coordinate for that branch should be placed.

7. When creating an area branch, we can go back and adjust clicked coordinates: Press the M key (shortcut to Move Coordinates mode) or right-click and choose Move Coordinates from the context menu. Click the coordinate to be moved, and then drag it as desired to a new location.  To continue the branch, right-click and choose Continue Last Branch.  

8. After clicking the last coordinate for the last branch, to commit changes right-click anywhere in the drawing and choose Save Changes from the context menu, or press the Add Record button in the Info pane Coordinates tab.  

9. To abandon changes, right-click and choose Undo Changes, or switch to a different layer.   

We can use keyboard shortcuts to save changes or to undo changes.  Ctrl-Enter to save changes, and Ctrl-Backspace to undo changes.

Switch Back to Default Navigation Mode

 After creating areas, lines, or points, switch the mouse cursor mode back to Default navigation mode.   Click the cursor mode button and choose Default.

Shortcut: Press Shift-Space to get back to Default navigation mode.

There is no harm done if we forget, since immediately any cursor clicks in the active window will begin to create whatever object had been previously created.  We can press Ctrl-Backspace or Right-click and choose Undo Changes to abandon the edits, and no object will be created.

Editing Existing Points, Lines and Areas

To edit an existing object, Alt-click on the object to pick that object for editing.  The Info pane immediately pops open to display the Values tab, with the object's attributes enabled for editing.    To edit geometry, click on any of the object's vertices or segments.   The Info pane immediately switches to the Coordinates tab, with the object's vertices enabled for editing.    A vertex is one of the coordinates that defines an object.   Many GIS packages use the term vertex instead of coordinate.  Manifold uses both words as synonyms.

See the Example: Change the Shape of Areas topic for step-by-step illustrated examples of the following procedures.

Move a vertex in an object:

1. Alt-click the object to pick it for editing.   Blue boxes appear at the vertices that define the object, and the system automatically pops open the Info pane Values tab.  

2. Click on the vertex to be moved.  The editing session switches into Move Coordinates mode and the clicked vertex is shown with a larger blue box to show it is the active vertex.  Drag the active vertex to whatever position is required.

3. Click any other vertex to be moved, and then drag that vertex as desired to a new location.

4. Press Ctrl-Enter or the Update Record button for the change to take effect.  To abandon changes, press Ctrl-Backspace.

To save changes or to undo changes we can also right-click into the drawing and choose Save Changes or Undo Changes.

Move multiple vertices together:

1. Alt-click the object to pick it for editing.   Blue boxes appear at the vertices that define the object, and the system automatically pops open the Info pane Values tab.  

2. Click on first vertex in the set to be moved.  The editing session switches into Move Coordinates mode and the clicked vertex is shown with a larger blue box to show it is the active vertex.  

3. Ctrl-click on that vertex to select it, and Ctrl-click on all other vertexes to be moved together to select them as well.  Their boxes will darken as well, to show they are selected.

4. Drag the bigger darkened vertex to the desired position.   All other selected vertices will move along with that box.

5. The system will preview the result using blue preview color. Press Ctrl-Enter or the Update Record button for the change to take effect.  To abandon changes, press Ctrl-Backspace.

To save changes or to undo changes we can also right-click into the drawing and choose Save Changes or Undo Changes.

Move an entire object:

1. Alt-click the object to pick it for editing.   Blue boxes appear at the vertices that define the object, and the system automatically pops open the Info pane Values tab.  

2. Click on the vertex that is most convenient to use as a handle to move the object.   The editing session switches into Move Coordinates mode and the clicked vertex is shown with a larger blue box to show it is the active vertex.  

3. Shift-Drag the active vertex to whatever position is required.  All other vertices, that is, the entire object, will move along with that vertex, thus moving the entire object.

4. The system will preview the result using blue preview color. Press Ctrl-Enter or the Update Record button for the change to take effect.  To abandon changes, press Ctrl-Backspace.

To save changes or to undo changes we can also right-click into the drawing and choose Save Changes or Undo Changes.

Another way to move an entire object is to select all vertices in the object and to then drag any one of them as desired.  Since all selected vertices move together when any one of them is moved, the entire object will move.

Delete a vertex from an object:

1. Alt-click the object to pick it for editing.   Blue boxes appear at the vertices that define the object, and the system automatically pops open the Info pane Values tab.  

2. Click on the vertex to be deleted.  The editing session switches into Move Coordinates mode and the clicked vertex is shown with a larger blue box to show it is the active vertex.  

3. Right-click on that vertex and choose Delete Coordinate in the menu.

4. The system will preview the result using blue preview color. Press Ctrl-Enter or the Update Record button for the change to take effect.  To abandon changes, press Ctrl-Backspace.

To save changes or to undo changes we can also right-click into the drawing and choose Save Changes or Undo Changes.

Delete multiple vertices from an object:

1. Alt-click the object to pick it for editing.   Blue boxes appear at the vertices that define the object, and the system automatically pops open the Info pane Values tab.  

2. Click on a vertex to be deleted.  The editing session switches into Move Coordinates mode and the clicked vertex is shown with a larger blue box to show it is the active vertex.  

3. Select all vertices to be deleted by Ctrl-clicking them or by using a Ctrl-drag selection box.

4. Right-click on any of the selected vertices and choose Delete Coordinate in the menu.

5. The system will preview the result using blue preview color. Press Ctrl-Enter or the Update Record button for the change to take effect.  To abandon changes, press Ctrl-Backspace.

To save changes or to undo changes we can also right-click into the drawing and choose Save Changes or Undo Changes.

Add vertices to an object using Insert Coordinates:

1. Alt-click the object to pick it for editing.   Blue boxes appear at the vertices that define the object, and the system automatically pops open the Info pane Values tab.  

2. Click on the segment where the vertex is to be added.  The editing session switches into Move Coordinates mode and the vertex at the beginning of the segment is shown with a larger blue box to show it is the active vertex.  

3. Right-click into the drawing (but not onto the segment) and choose Insert Coordinates mode, or press the I key as the keyboard shortcut to enter Insert Coordinates mode.

4. The line for the segment will now rubber-band to follow the mouse cursor, allowing us to click to insert new vertices.  

5. Delete the last-clicked vertex, if desired, with Backspace.  We can repeatedly backspace to delete all added vertices in the current branch.

6. The system will preview the result using blue preview color. Press Ctrl-Enter or the Update Record button for the change to take effect.  To abandon changes, press Ctrl-Backspace.

To save changes or to undo changes we can also right-click into the drawing and choose Save Changes or Undo Changes.

Add a vertex to an object using Move Coordinates + Split:

1. Alt-click the object to pick it for editing.   Blue boxes appear at the vertices that define the object, and the system automatically pops open the Info pane Values tab.  

2. Click on the segment where the vertex is to be added.  The editing session switches into Move Coordinates mode and the vertex at the beginning of the segment is shown with a larger blue box to show it is the active vertex.  

3. Right-click into the drawing (but not onto the segment) and choose Move Coordinates + Split mode, or press the P key as the keyboard shortcut to enter Move Coordinates + Split mode.

4. Click onto the segment where the new vertex is to be inserted.  The segment will split into two segments at that spot, with a new vertex inserted.

5. The system will preview the result using blue preview color. Press Ctrl-Enter or the Update Record button for the change to take effect.  To abandon changes, press Ctrl-Backspace.

To save changes or to undo changes we can also right-click into the drawing and choose Save Changes or Undo Changes.

Add a vertex to an object using Add Mid Coordinate:

1. Alt-click the object to pick it for editing.   Blue boxes appear at the vertices that define the object, and the system automatically pops open the Info pane Values tab.  

2. Click on the segment where the vertex is to be added.  The editing session switches into Move Coordinates mode and the vertex at the beginning of the segment is shown with a larger blue box to show it is the active vertex.  

3. Right-click onto the segment where the new vertex is to be inserted, and choose Add Mid Coordinate from the menu.  The segment will split into two equal segments, with a new vertex inserted at the mid point.

4. The system will preview the result using blue preview color. Press Ctrl-Enter or the Update Record button for the change to take effect.  To abandon changes, press Ctrl-Backspace.

To save changes or to undo changes we can also right-click into the drawing and choose Save Changes or Undo Changes.  

To summarize options for committing or abandoning edits:  We commit edits by pressing Update Record in the Info pane, or by pressing Ctrl-Enter, or by right-clicking anywhere and choosing Save Changes.   We can abandon edits, not making any changes, by right-clicking anywhere and choosing Undo Changes, or by switching to another layer, or by choosing a different cursor mode, or by pressing Ctrl-Backspace.   Esc exits editing mode if there are no uncommitted changes.  

Tech tip:  How we choose to add vertices to an object depends on our taste and the workflow.   Using Move Coordinates + Split is convenient when adding coordinates in many different locations to reshape a line or area.  In that mode we can simply click wherever we want a vertex added in a segment and then we can drag it as we like to a desired location.   Using Insert Coordinates mode is convenient when we want to sequentially grow additional vertices within a segment by click, click, clicking where want those vertices.

See the Info pane topic for additional info.  For example, we can modify a point, line, or area by loading a saved object from a Manifold coordinate format file, and we can modify a line or area by loading a traverse file in ESRI traverse file format, as shown in the Example: Create Parcels from Traverse Files topic.

Example: Edit Attributes

Alt-click an object to edit that object's attributes.  Small blue boxes appear at the vertices that define the object, and the system automatically switches to the Info pane Values tab.  

The Values tab shows attributes for the designated object.   Attributes which cannot be edited, such as geom data type values or key fields such as mfd_id used for the primary index, will be shown with gray background color.  Attributes which may be edited are shown with white background color.  Editing an attribute value is just like editing a cell in a table.  

To edit an attribute, Double-click into the value cell and enter the value desired.   Press Enter to stop editing.  Just as with editing a cell in a table, the edited cell will be shown in blue preview color.   To commit the edit, press Ctrl-Enter or click the Update Record button.  To abandon the edit, press Ctrl-Backspace.

Right-clicking onto an attribute cell pops open a context menu.   We can right-click onto a cell, choose Copy and then right-click onto a destination cell and  choose Paste to paste the copied value into the destination cell.

The Edit choice allows us to view and to edit longer text in a larger dialog that is more suitable for multi-paragraph text than the space available in a single cell.

To commit the edit, press Ctrl-Enter or click the Update Record button.  To abandon the edit, press Ctrl-Backspace, or right-click into an empty part of the map and choose Undo Changes.  

Example:  Edit Object Geometry

To edit an existing object:

• Alt-click an object to pick it for editing in the Info pane and in the map window.  Blue boxes appear at the vertices that define the object, and the system automatically switches to the Info pane Values tab.   
• Click any vertex or segment in the object to mark the vertex as the active vertex, which switches the Info pane to the Coordinates tab, and puts the object into editing mode.

We can also switch the object into editing mode by clicking the Coordinates tab in the Info pane, or by right-clicking anywhere in the map window and choosing Edit Coordinates.  

• Click any vertex to mark it as the active vertex and then drag it to a new location, or edit the coordinates for that vertex in the Coordinates list in the Info pane.  
• Ctrl-click vertices in the map window or in the Coordinates list to select them, showing them in dark blue.   Any action applied to a selected vertex will apply to all selected vertices.

When selecting vertices of an object that is in editing mode, all of the usual mouse selection moves work.  For example, we can select many vertices by using Ctrl-drag to draw a selection box around them in the map window.  In the Coordinates tab list, we can Ctrl-click a coordinate row and then Shift-Ctrl-click another coordinate row and both rows and all in between will be selected.

In the illustrations below we select two vertices by Ctrl-clicking them (either in the map window or in the Coordinates list) and then we press Delete to delete all selected vertices.

When we delete the coordinates in the list, the object snaps into the new shape, shown in provisional, blue color over the current shape. Press Ctrl-Backspace to abandon the changes.

Press the Update Record button or Ctrl-Enter to apply the changes.    We can also right-click into the drawing and choose Save Changes or Undo Changes.

A shortcut:  If we have switched into editing geometry mode, we can switch back to the Values tab, and thus back to viewing and editing attributes mode, by clicking a spot in the drawing somewhat away from the object.    We can also, of course, click on the Values tab in the Info pane.

Selecting Vertices

We pick an object for viewing and editing attributes by Alt-clicking it.  We then click a vertex or segment to switch into Move Coordinates mode, our basic editing mode for dragging vertices to new positions.   In addition to clicking a vertex to make it the active vertex, we can also select vertices to apply the same editing action, like a move, to all of the selected vertices at once.  Selected vertices appear with dark blue edit handles.

We select vertices using the same moves we use to select objects in drawings:

• Ctrl-click a vertex to select it.

• Shift-Ctrl-click a vertex to deselect it.

• Ctrl-drag a selection box select all vertices within the box.

• Shift-Ctrl-drag a selection box to deselect all vertices within the box.

Selected objects in drawings are shown in red selection color.   Selected vertices in an object picked for editing are shown in dark blue color, but their corresponding rows in the Coordinates list in the Info pane are shown in red selection color.

Example: Selecting Vertices

A powerful capability when creating new objects or editing existing objects is the ability to select one or more vertices that can be moved or deleted together.   Selection for vertices uses the same mouse move commands used for selection in general.   A visual difference is that selected vertices are shown in dark blue color instead of red color.    That avoids visual confusion with any objects that are selected in the drawing.

In the illustrations below we have Alt-clicked an area to pick it.   

To switch into Move Coordinates mode, the default editing mode, we click any vertex or any straight line segment. Editing handles immediately grow slightly in size with the edit handle for the active vertex growing even larger to show that is the active vertex.  If we clicked a vertex, that will be the active vertex.  If we clicked a segment, the vertex at the beginning of the segment will be the active vertex.   

To select a vertex, we Ctrl-click it.   We can Ctrl-click more than one vertex to select it.  

Ctrl-click a vertex and the vertex immediately is re-colored in dark blue color, to show it has been selected.  We Ctrl-click the next vertex, to select that vertex as well.  It switches to dark blue color to show it has been selected.

The usual selection mouse commands work.  For example, we can Ctrl-drag a selection box to select all vertices within the box.    We can Shift-Ctrl-drag a deselection box to deselect all vertices within the box.

To make a different vertex the active vertex, we can Click it, or we can click a straight line segment with the desired vertex at the beginning.  That will not change the selection state of the vertex.   If we want to deselect a vertex, we can Shift-Ctrl-click it.

If we drag the active vertex to move it, all selected vertices will move with it.    To apply the move, right-click and choose Save Changes, or press Ctrl-Enter as a keyboard shortcut, or press the Update Record button in the Info pane.

When changes are applied, the object changes based on how we moved vertices.  It is still picked, but no longer in Move Coordinates mode.

Straight or Curved Segments

When a drawing displays objects such as areas, lines or points, each object is drawn based on the set of coordinate locations, called coordinates for short,  that defines it.   In this short-hand nomenclature a "coordinate" is really a short hand way of saying a "coordinate pair," that is, two coordinates that consist of an X coordinate number and a Y coordinate number.   A synonym for such a coordinate location that defines an object is the word vertex.   This documentation uses both coordinate and vertex as synonyms.

A single point is defined by a single coordinate.  Lines and areas are more complex than points because they involve lists of coordinates.   Lines and areas consist of a sequence of coordinates that define them, with segments between those coordinates making up the line or the borders of an area.  

Most GIS systems (including all Manifold GIS products before Release 9) use only straight segments between coordinates to draw lines and areas.   In such systems a line that may appear to be a smooth curve when the view is zoomed out will be seen when the view is zoomed in to be made up of a sequence of straight line segments, each segment being defined by the coordinates at each end of that segment.  Such lines consisting of straight line segments are often called polylines in other GIS systems.   Manifold uses the words line and polyline as synonyms.

Likewise, an area will be defined by a set of coordinates that when linked by straight segments define the boundary of the area object as well as the boundaries of any internal "holes" or external "islands."   When the view is zoomed out such areas might look to be smoothly curved shapes, but upon closer inspection will be seen to be made up of straight segments that define their boundaries.  Because such areas are made up of straight line segments, areas are often called polygons in other GIS systems.   Manifold uses the words area and polygon as synonyms.

A more complex way of defining objects in vector-based drawings is to use curved segments between coordinates, the precise shapes of the curved segments being defined by mathematical formulae based on the beginning and end coordinates, plus one or more control points that precisely define the shape together with the beginning and end coordinates.   For example, a circular arc can be defined by three coordinates: two coordinates to define the beginning and end of the arc plus a third coordinate through which the circular arc must pass.  Given three such coordinates a simple mathematical relationship defines at any desired level of resolution the shape of a circular arc which passes through those three locations.

In Manifold, the segments which make up lines or areas can be either straight segments between coordinates or curved segments between coordinates, with a mix of straight and curved segments allowed in the same object.  The curved path of curved segments is mathematically computed on the fly based upon the coordinates that anchor the beginning and end of the curve plus any control points that define the curved segment.  

Quicker than constantly saying writing curved segment or curvilinear segment is to simply use the word arc, leveraging that word's meaning as a section of a circle, to refer to circle arcs, ellipse arcs, and spline arcs, the three types of curved segments used in Manifold.

Manifold uses three types of curved segments, arcs, in addition to straight line segments:

Line segment - (default) Straight line segment between beginning and end coordinates.

Circle arc  - A curved segment that is a circular arc, defined by beginning and end coordinates, plus one control point that sets the radius and placement of the circular arc relative to the beginning and end coordinates.

Ellipse arc  - A curved segment that is an ellipsoidal arc, defined by beginning and end coordinates, plus three control points.   The first axis of the ellipse is defined by the beginning and end coordinates.  One of the control points chooses the side of the ellipse the arc is on. Another control point specifies the center of the ellipse.  A third control point defines the orientation and the second axis of the ellipse.   Using three control points plus beginning and end coordinates is a classic user interface for specifying ellipse arcs, but can does result in ambiguities.  Manifold resolves any ambiguities by building an ellipse that primarily follows the control points and then, if necessary, is bent at the beginning and the end to connect to the beginning and end coordinates.

Spline arc - A curved segment that is a spline defined by beginning and end coordinates, plus three control points which define the curve by defining tangents, so the spline tends to run toward each control point in turn without going through a control point.

The illustration above shows a single line that contains both curved segments and straight segments.  It consists of a circle arc segment followed by four line segments followed by a spline arc.  The small dot on the circle segment and the small dots above and below the spline segment are not point objects but are control points for defining the circle arc and the spline.   Those small dots can be clicked and then dragged to adjust the shape of the circle segment and the shape of the spline segment.

Curved segments are created in Manifold by first creating a straight segment and then right-clicking that segment and choosing Convert to... the desired type of curved segment from the context menu.

See the Measurements topic for a step-by-step example using curved segments in a path.  See also the Editing Drawings - Create Lines with Curves video for a live action example creating lines with curved segments.

To add a curved segment when creating a new line or area:

1. Begin creating the object in the usual way, using Create Line or Create Area.

2. Click to create coordinates, creating a straight line segment where the curved segment will go.

3. Enter Move Coordinates mode by pressing the M key (keyboard shortcut to Move Coordinates mode) or right-clicking and choosing Move Coordinates from the context menu.

4. Right-click the straight segment to be converted into a curved segment, and then in the context menu choose the Convert to... choice for the type of curved segment desired.  

5. Adjust the shape of the curved segment as desired by clicking a control point for the curved segment and then dragging that control point as desired.

6. If the curved segment is a spline, to add another control point to the spline, right-click an existing control point and choose Add Spline Coordinate from the context menu.  A new spline control point coordinate appears in the spline approximately midway between the right-clicked control point and the next control point or terminal coordinate of the spline.  It automatically becomes the active coordinate and can then be dragged as desired to reshape the spline.

Create a curved segment in an existing object:

1. Alt-click the object to pick it for editing.   Blue boxes appear at the vertices that define the object, and the system automatically pops open the Info pane Values tab.  

2. Switch into Move Coordinates mode, by clicking any vertex or straight line segment, or by clicking the Coordinates tab in the Info pane.  

3. Right-click the straight segment to be converted into a curved segment, and then in the context menu choose the Convert to... choice for the type of curved segment desired.  

4. Adjust the shape of the curved segment as desired by clicking a control point for the curved segment and then dragging that control point as desired.

5. If the curved segment is a spline, to add another control point to the spline, right-click an existing control point and choose Add Spline Coordinate from the context menu.  A new spline control point coordinate appears in the spline approximately midway between the right-clicked control point and the next control point or terminal coordinate of the spline.  It automatically becomes the active coordinate and can then be dragged as desired to reshape the spline.

Convert curved segments to a sequence of straight segments

1. By default, the Transform pane applies the operation to all objects in the drawing.  To do a conversion only on selected objects, Ctrl-click the objects to be converted, to select them.  They appear in red selection color.

2. In the Transform pane, choose that drawing layer and the geom field in that drawing.

3. Double-click the Clean template.  Choose the convert curves to lines operation.  Choose the number of straight segments desired to replace the curved segment.

4. Check the Transform selection only option to convert only selected objects.

5. If desired, press Preview to get a preview of what will happen.   Press Transform to apply the transform.

Convert a curved segment to a single straight segment

1. Alt-click the object to pick it for editing.   Blue boxes appear at the vertices that define the object, and the system automatically pops open the Info pane Values tab.  

2. Switch into Move Coordinates mode, by clicking any vertex or straight line segment, or by clicking the Coordinates tab in the Info pane.  

3. Right-click a control point coordinate handle for the curved segment to be converted, and then in the context menu choose Convert to Line.  

To save changes or to undo changes we can also right-click into the drawing and choose Save Changes or Undo Changes.

As a practical matter, most people doing GIS will use straight line segments for lines and areas.   Few GIS systems do a good job of supporting curved segments, so there is much less data published using curved segments.   Manifold's ability to work with curved segments allows us to use that data within Manifold in a limited way, at least for display and interactive editing.  

However, most processing tools in Manifold, such as Transform templates and various Geom SQL functions, do their work by first converting a curvilinear segment into a straight line segment between the same two start and finish coordinates.  That will often lead to weird or otherwise unexpected results.  To avoid such problems, first convert curvilinear segments into equivalent constellations of straight line segments at whatever resolution is desired, using the Clean transform template with the convert curves to lines operation option and the number of linear segments desired to approximate the curve in the Curve limit parameter.

Basic Editing Commands

Basic keyboard and mouse commands when creating new objects or editing existing objects:

Context Menus Reference Guide

When creating objects or in Insert Coordinates editing mode at the end of object paths, a right-click launches a context menu like that at left below:

With Move Coordinates mode, or using Insert Coordinates editing mode on segments within a path, a  right-click launches a context menu like that at middle above.  When editing existing objects we also get a Merge command, as seen at right above.

Default object creation mode is Insert Coordinates, where every click inserts a new vertex.  

We can switch to Move Coordinates mode at any time when creating or editing an object, by right-clicking and choosing Move Coordinates  from the context menu. A quick keyboard shortcut is to press the M key.  Clicking the Coordinates tab also switches to Move Coordinates mode when editing an existing object.

Switching to Move Coordinates puts the object into coordinate editing mode, where we can alter the object by first clicking a vertex and then dragging that vertex to move it to a new location, or by right-clicking onto a segment to add a mid point coordinate or to convert it between linear or curvilinear segment types.    Switching to Move Coordinates + Split also puts the object into coordinate editing mode, just like Move Coordinates mode, but with an added implied Split command.   The command is implied because we use it by simply clicking onto a segment to split the segment into two segments, inserting a new vertex at that spot.   This is a different command than using the Split interactive editing command that uses a path line to cut areas and lines into parts.

When in Move Coordinates or Move Coordinates + Split mode, a right-click on a segment provides more choices:  

The context menu at left, above appears when creating a new object we switch to Move Coordinates mode and then right-click onto a segment already created.  The context menu at right, above appears when we edit an existing, already-created object, in Move Coordinates mode right-clicking onto a segment.    Note that the context menu for an existing object contains a Merge command.

The Reverse Branch Direction command appears for lines, but not for areas, since direction of branches in areas depends on whether their geometry is ESRI-style direction or OGC-style direction.

Additional commands: When editing, additional commands depend upon the context in which the segment is right-clicked:

In either Move Coordinate mode, a right-click on a vertex calls up an expanded context menu:  

• Illustration above left: right-click on any vertex when creating a new object.  
• Illustration above center: right-click on an inner vertex when editing an existing object.  
• Illustration above right: right-click on an ending vertex (the first or last vertex) when editing an existing line.

Note that the context menus for an existing object contain a Merge command.

Vertex context menu commands: When editing, additional commands depend upon the context in which the vertex is right-clicked:

Insert Coordinates when Creating New Objects

Most frequently, we create new objects, such as creating a new line, by clicking the locations for coordinates (vertices) one after another.    However, in the middle of creating a new line we may notice we skipped one or more coordinates we wanted.  We would like to go back and to insert those.    To insert those coordinates into an existing segment we first switch to Move Coordinates mode, and then we click the vertex beginning the segment where we would like to insert some more coordinates.   We then switch back to Insert Coordinates mode begin clicking to add coordinates as desired.  When done, we right-click to get the following context menu:

Choosing Continue Last Branch will jump the context for the Insert Coordinates action to the last vertex of the object, so we can keep on clicking to grow the object from the end.   See the Example: Add Vertices in the Middle of a Line being Created topic for an illustrated example.

Expanded Context Menus

After we have clicked at least once when creating a new object or path line, the right-click context menu expands for more choices, shown below, with the menu when creating objects at the left and the menu for the Draw Path tool, used for measurements and editing, at right.

Split appears when at least two vertices have been clicked, and Erase appears for areas when at least three vertices have been clicked.  

Editing Modes

The same right-click context menu allows us to control snap modes and editing modes.   When creating new objects in a drawing, or creating a path line, the default creation/editing mode is Insert Coordinates, where every click inserts a new vertex.  

To edit an existing object, we first pick it by Alt-clicking the object, and then clicking any vertex or segment in that object.  That switches to Move Coordinates mode.  We can also switch to Move Coordinates mode at any time when creating a new object, by right-clicking and choosing Move Coordinates  from the context menu.  That allows us to go back and change parts of a new object that we have already created, when we are still in the process of creating that new object.   For example, when we are creating a complex object and we notice we have made an error near the beginning, we can go back and correct that error and then continue on creating the object from where we left off.

When using the path tool, switching to Move Coordinates puts the path line into edit mode, where we can alter the created line by clicking on and then clicking and dragging a vertex to move it to a new location, or by right-clicking onto a segment to convert it between linear or curvilinear segment types.   

Switching to Move Coordinates + Split also puts the path line into edit mode, just like Move Coordinates mode, but with an added implied Split command.   The command is implied because we use it by simply clicking onto a segment to split the segment into two segments, inserting a new vertex at that spot.    This is a different command than using the Split interactive editing command that uses a path line to cut areas and lines into parts.

When in Move Coordinates or Move Coordinates + Split mode, a right-click on a segment provides more choices.  A right-click on a vertex in those modes will provide the Continue Last Branch choice but not the Convert choices made available for segments.

Typical context menus in Move Coordinates mode when right-clicking onto a segment are shown below:

Shown at left above is the context menu when drawing a new object, in the center for an existing object and at right above the equivalent menu for the Draw Path tool.

Menu Options

Notes

Blue color used in editing - Objects that are picked for editing, as well as paths drawn by the measurement tool and in editing, have their coordinate edit handles and boundaries shown using the same blue color used for previews and for provisional edits in other settings. If desired, we can change the preview and provisional color used by Manifold in the Tools - Options dialog.   This allows us to use a color different than blue color in cases where a visual display already uses very much blue color or to provide a more discernible color in case of color blindness.

What is a multipoint?  - A really bad idea for most people in most cases.  A multipoint is a single point object that has multiple coordinates, giving the appearance of multiple points.  The result is what appears to be many points but which are all one object in one record.  A multipoint can even have multiple branches, each of which has multiple coordinates.   Given that virtually everyone expects what visually seems to be a separate point to be, indeed, a separate point with its own record in a table, the use of multipoints is a sure-fire way to confuse people.  For that reason, even if it seems to make sense to use a multipoint, friends don't let friends use multipoints, and the user interface deliberately makes it difficult to create a multipoint by accident.

Inserting into multipoints - Multipoints are a strange enough idea, but even within that strange idea lie even stranger things:  A multipoint can be branched object, that is, with the points-within-the-same-point object being grouped into branches.  If we pick a multipoint for editing and switch into Insert Coordinates mode, the next inserted coordinate/vertex/point will always be at the end of the coordinate list.   That is, it will always be added as the last coordinate of the last branch of the multipoint.  

Deletions are Confirmed - Deleting objects in a drawing window or in a drawing layer in a map window displays a confirmation dialog. The default button in the confirmation dialog is set to Cancel.  If we do not want to see the confirmation dialog, we can check the Never show this again box.  That will remove the confirmation dialog for deleting frames in layouts, for deleting objects in drawing layers, for deleting labels, and for deleting records in tables.    Another way to eliminate the confirmation dialog is to uncheck the Confirm deleting records box in the Tools - Options dialog.  Objects in a drawing are records in the drawing's table, hence the "records" terminology.

Coordinate deletion logic - Logic for deleting coordinates when editing geometry in a map window tries to achieve sensible outcomes:

• Deleting coordinates will automatically delete ellipse arcs that became incomplete.

• Deleting coordinates for a line or an area deletes finished branches that became incomplete.

• When deleting coordinates in Insert Coordinates mode, a deletion does not always deletes the insert coordinate, switching away from Insert Coordinates mode. Instead, the location of the insert coordinate is checked after the deletion and if it remains valid, the insert coordinate is kept.

• Deleting coordinates does not always resets the focus coordinate to coordinate zero. If the focus coordinate remains valid after the deletion, the focus coordinate is kept. Otherwise, the focus coordinate is set to the closest (in list order) remaining coordinate in the same branch as the deleted focus coordinate.

• Deleting coordinates no longer always closes the last branch. If the last branch is opened, it is kept opened.

Ending branches with too few vertices - Defining an area, or a single branch in an area, requires at least three coordinates.  Likewise, defining a line requires at least two coordinates.  Attempting to end a branch of an area using Shift-click does nothing if the branch clicked so far contains less than 3 coordinates.   If we use right-click and then End Current Branch in the context menu to attempt to end the current branch of a line or an area, the command will first pad the branch to two coordinates for a line and three coordinates plus a closing coordinate for an area.

Alt-click details - Using Alt-click or Shift-Alt-click picks an object only when the cursor is in Default navigation mode.   In default navigation mode, Alt-clicking or Shift-alt-clicking a picked record has no effect: it simply leaves the same record picked.  Alt-clicking or Shift-alt-clicking a location where multiple objects overlap has no effect if a picked record overlaps that same location: it simply leaves the same record picked.   If the cursor is in some other mode, like Create Point, or Draw Path, the Alt modifier is ignored and an Alt-click works the same as a click, with the exception that when an object is not being actively edited (edits have just been saved or have just been undone), an Alt-click to pick or a Ctrl-click to select will pick or select the clicked object, switching back into default navigation mode.  That exception is a shortcut that allows jumping directly from some Create... mode or Draw Path mode straight into work on the next object of interest.

Selecting a Picked Object - When we Alt-click an object we cannot Ctrl-click it in the map window to select it.  We can, however, open the drawing's table and Ctrl-click the record for that object in the table to select it.

Ctrl-click and Ctrl-drag for selection (objects or coordinates) - Using Ctrl-click and Ctrl-drag in Default cursor mode with no picked object being edited selects objects.   Using Ctrl-click or Ctrl-drag with a picked object that is being edited (for example, in Move Coordinates mode) will select coordinates / vertices in that object.

Ctrl-click and Ctrl-drag details - Using Ctrl-click and Ctrl-drag for selection has similar effects with very small Ctrl-drag motions, and Ctrl-click is designed to work when clicking very close to objects.   Ctrl-drag in a map window will not slightly extend the selection box to make a single pixel box work as Ctrl-click would. Instead, Ctrl-click selects data within some distance of the click, but Ctrl-drag is allowed to make the selection box as thin as possible:  the window only starts tracking the box if the cursor is dragged far enough from the initial click point.

Clicking on whole number coordinates - Sometimes when creating objects in drawings, or labels in a labels component, for example, when using Manifold as a CAD editor or using Manifold to create diagrams for illustrations, we would like the coordinates we click for objects to be whole numbers, such as X,Y values of -165, 40 and not -165.4954783999, 40.9398312223.   To do that, use Snap to Grid snap mode with Snap properties set to 1 unit,, as discussed in the Snap Modes topic.

Visual Display of Curved Segments  - Curved segments are computed on the fly using a mathematical formula to derive the precise shape of the curve based on beginning and end coordinates plus control points.  The mathematical basis of the curve provides a fundamentally analog, infinitely precise definition of the curve.

But because computers are digital devices that quantize values such as X,Y positions, the visual display of a what in mathematical theory is a perfectly precise curve will always be a visual approximation, as will computations on the curve.  The quantized approximation is analogous to how a precise curve on a computer display will always have "the jaggies" if we magnify our view to where we can see how individual pixels in the display quantize a smooth curve into a step-function of discrete pixels.

Computations will always happen on the curve to full precision possible in the computer, but a simplification is used for display purposes.  When displaying curved segments Manifold approximates their appearance by drawing the curved segment using multiple straight line segments that give the appearance of a curve.    The number of segments are chosen by a display algorithm that reckons the zoom level and considers how close the straight line segment approximation would be to the ideal curve at that zoom level.   If the approximation is too far off in some spots by more than some internally allowed number of pixels the algorithm chooses to use more segments to approximate the appearance of the curve.  

The algorithm normally produces reasonably appealing visual results but sometimes it estimates poorly and the resulting "curved segment" looks like a polygon made up of straight segments.  Changing zoom will show a smoother curve.  

Curved Segments are a Poor Choice for GIS  - Curved segments are primarily a CAD thing.   Manifold supports curved segments to facilitate import of such segments from CAD systems and other software that uses curved segments, but with the expectation that after import such curved segments will be transformed into straight segments that are more useful in GIS.  One hallmark of non-GIS software, such as CAD, tends to be that curvilinear constructions, such as splines, are used only within what ends up being always the same Cartesian coordinate system.    CAD systems, for example, do not usually feature re-projections into profoundly different coordinate systems that can radically change the shape of objects.   

GIS systems, however, do feature such radical changes where what once was straight rarely ends up being straight after a re-projection, and what once was a curve of known shape based on the locations of defining points and formulae using those points becomes a totally different curve in the new coordinate system.   Even a change in scale can cause radical changes in shape given the highly non-linear nature of most geographic projections.

For those reasons, curved segments in GIS tend to look right only within the scale and the coordinate system for which they were created.   Zoom in or out and the appearance of the curved segment can change significantly.  Change the coordinate system or transform the object's geometry and the result will most likely be nothing like the original curve.    Most transforms in Manifold will automatically replace a curve with a straight line segment.

For those reasons, using curved segments within GIS is almost always a mistake.  When creating new objects intended for GIS use it is almost always a very bad idea to create them as curved segments.   When working with objects that have been imported from other software and have curved segments it is usually a very good idea, often a required part of workflow, before using them in GIS as spatial data to first convert such curved segments into equivalent straight line segments that can be manipulated using well-known GIS infrastructure and transformations.

When creating new objects, for maximum precision we should always use straight segments in spatial work.   Curved segments can be pretty, but they end up being limiting.

Tech Tip:   Curved segments may be rendered in drawing windows as approximations that appear to be made up of straight line segments and not curves.  Rendering of curved segments in drawings depends greatly upon zoom level, coordinate system and other factors so that curved segments are normally rendered using straight segment approximations.   For illustrations and means to convert curved segments to straight segments see the Clean : convert curves to lines transform.

Videos

Editing Drawings - Create Areas - How to create areas (polygons) in a drawing.  We digitize a lake by tracing over a background satellite image layer from a web server.  This quick video shows how editing tools in Manifold make it easy to digitize objects very quickly, correcting any errors with no stress or fear of getting it wrong.  Includes a quick demo of snapping.

Editing Drawings - Create Lines with Curves - A very short video showing how to create lines in drawings using straight segments and also circular arcs.  We create a line in a map of Paris showing our walk around circular ponds. Manifold can create polylines using straight line segments for classic polylines, or using curved segments that are circular arcs, ellipses, or splines for very smooth curves, a much faster and easier technique than clicking many points.  Super!

See Also

Getting Started

User Interface

Cursor Mode

Drawings

Snap Modes

Clip

Erase

Merge

Split

Measurements

Copy and Paste between Drawings or Tables

Layers Pane

Info Pane

Example: Draw Lines, Areas and Points - Simple example of using basic mouse moves to add points, lines and areas to a drawing.

Example: Drawings use Geom Fields in Tables  - An essential discussion on how drawings are created from geom fields in tables, including how the drawing knows which coordinate system to use.

Example: Repair a Wrong Edit using a Backup - How to quickly make a backup table and to then copy and paste geometry from that table to repair errors made when editing objects.  This technique is a life-saver when edits go astray.

Example: Trace an Area in a Map over an Image Background - In a map with a drawing layer above an image layer, create an area object in the drawing by tracing over the outlines of something seen in the image layer below.

Example: Edit Coordinates While Creating an Object - When creating an object in a map using a tool such as Create Area, right in the middle of the process we can edit coordinates in the Info pane Coordinates tab.   This example shows the step by step process.

Example: Edit Attributes and Move a Point - We look at the attributes for a point in a drawing layer and edit one of the attributes using a more expanded Edit dialog.  We then move the point to a new location. Easy!

Example: Edit Attributes, Larger Text, IME for Asian Languages - A tour showing how to edit attributes in a drawing using the Info pane Values tab and the expanded Edit dialog, including advanced Unicode facilities and use of the built in Input Method Editor (IME) to input text in Japanese language.

Example: Create a Multipoint - This topic provides two examples:  First we create a multipoint and then next we create a multipoint having two branches.  The purpose of this topic is to help teach the implementation of geometry in Manifold and other spatial packages using an unusual and rarely met object type, the multipoint, which combines what appear to be many separate points into a single multipoint object.

Example: Change the Shape of Areas - Step-by-step editing of an existing area in a drawing: changing the shape by moving a vertex, by moving several vertices together, by moving the entire object, by deleting a vertex and by adding a vertex.

Example: Edit Areas in a Layer to Align with Another Layer - Editing areas in one layer so their boundaries align, either all or in part, with boundaries of areas in a different layer is a common task in GIS and CAD. For example, we might want area boundaries in a layer with different zoning areas for tax or regulatory purposes to be guided by the boundaries of administrative jurisdictions, such as the boundaries of cities, in a different layer.  This example shows how, using fast and simple techniques.  

Example: Add Vertices in the Middle of a Line being Created - During the creation of a new object we can go back and make corrections, additions and deletions to coordinates already marked.  In this example we start creating a new line, and then notice we have skipped over some locations we wanted to click.  We go back to add those vertices (coordinates), and then we continue with creating the line.

Example: Create Parcels from Traverse Files - Traverse files using ESRI traverse file format are widely used by surveyors and government organizations in the US to define parcels and lines by describing a sequence of directions, distances and curves from a starting point.  Manifold automatically handles both tangent and non-tangent curves in ESRI traverse file format as well as the full variety of options used to specify angles, distances and curves.  This video shows how it's easy to create a parcel from a traverse file.

Example: Edit Covered Objects - Working with drawings where some areas completely cover smaller areas is a bad idea, but sometimes we have to work with data in that form whether we like it or not.   This topic shows techniques that can help us select and edit objects that are completely hidden by higher objects.

Videos

Editing Drawings - Create Areas - How to create areas (polygons) in a drawing.  We digitize a lake by tracing over a background satellite image layer from a web server.  This quick video shows how editing tools in Manifold make it easy to digitize objects very quickly, correcting any errors with no stress or fear of getting it wrong.  Includes a quick demo of snapping.

Editing Drawings - Create Lines with Curves - A very short video showing how to create lines in drawings using straight segments and also circular arcs.  We create a line in a map of Paris showing our walk around circular ponds. Manifold can create polylines using straight line segments for classic polylines, or using curved segments that are circular arcs, ellipses, or splines for very smooth curves, a much faster and easier technique than clicking many points.  Super!

Speed Demo - 22 Million Roads - See the phenomenal speed of Manifold, popping open a project with 22 million vector roads at once with instantaneous opens and  instantaneous, no-delay panning and zooming, even when reprojecting 22 million vector objects on the fly.  Amazing!  This demo opens a 10GB project of all roads in the continental US, over 22 million of them, in 1/10th of a second and then pans and zooms instantly. Everything goes super-fast, not just viewing but editing too: We open a second project with over 842,000 roads in Pennsylvania and copy and paste those into the 22 million line project in seconds.  Find and display entire counties of roads by FIPS number instantly.  You get all this speed using Manifold alone on a typical desktop machine, doing tasks that are impossibly slow in other GIS packages.

Manifold Future - Future Tour Part 1 - This video shows how to download and use a portable installation for Manifold Future.  The video also shows the Contents, pane, layers and layer opacity, one click use of data source favorites, using your own archival favorite and getting record values instantly.  If you are using Viewer or Radian Studio, download and use the Future version to get access to all these powerful new features.

Manifold Future - Future Tour Part 2 Editing - The video shows how to create new objects, how to add fields and vertices and move vertices around, how to edit existing objects and how to use simple selection methods to choose vertices to move together, including moving all objects.

Manifold Future - Future Tour Part 3 Editing - The editing tour continues with a look at how to create branched objects, including how to create areas with holes and islands, how to add branches to lines and how to add coordinates between vertices in existing objects.  We finish up by creating an area that traces over a pond in the Luxembourg Gardens in Paris using a Google satellite view, and then we add a hole to that area and two additional islands.

Manifold Future - Future Tour Part 4 Edit Attributes, Move a Point - We use Manifold Future to see how to view attributes of objects in drawings, including use of the new Edit dialog to view long, multi-paragraph text fields.  We edit fields and see how easy it is to preview edits and either accept them or abandon them. We switch to editing the geometry of objects in a drawing, viewing the coordinate locations and using mouse moves to reposition points. We edit the location of a point to correct an error in a drawing, using Google Satellite view to provide context for the correction.  Fast and easy, with previews all the way!

Manifold Future - Future Tour Part 5 Unicode Attributes and IME -  We take a tour through Manifold Future attribute editing, showing how to edit attributes in a drawing using the Info pane Values tab and the expanded Edit dialog, including advanced Unicode facilities and use of the built in Input Method Editor (IME) to input text in Japanese language.