The Layers pane provides a render scale setting that works with layers which are drawings (vector layers) and labels. The render scale setting is very similar to what Esri calls a reference scale.
Specifying a render scale setting for a layer locks the rendering of that layer within a desktop window or within a layout frame to that specific scale, with vector symbology and labels. Zooming the window or frame closer will increase the size of the symbols or labels, while zooming the window or frame farther out will decrease the size of the symbols or labels. When specified, the render scale value applies during rendering on screen in windows and also during printing of layouts or print previews.
A render scale setting is used to get a display on screen that matches what will be seen in a printed copy at that scale. By locking a layer to a given render scale that is the same scale that we would like to use in a printed version, we can see what the final print version will look like when creating layouts.
The examples in this topic are taken from the project seen above, where we have used the Style pane to assign point symbols in the temples and the amphitheatres layers. We have also created labels layers for the objects in those layers. The illustration shows part of modern Nîmes, France where a famous Roman temple and amphitheater are located.
The illustration above shows a zoom scale of 1:20,000 in use for the window. We plan on creating printed versions at a scale of 1:20,000, so we will use the on-screen version in the map window at that scale to arrange a reasonable size of text for labels and sizes of symbols for points. The symbols in the temples and the amphitheatres layers have been thematically formatted by a ranking field, so that better preserved temples and arenas will have larger symbols.
For a larger illustration size we will work with an undocked map window in this topic.
With the focus on the map window, the Layers pane shows the layers in the map. By default, it reports the opacity of each layer. We will switch that to reporting the Render Scale value, if any. Click on the filter button and choose Show Render Scale.
By default, all of the drawing and labels layers have no render scale value.
Without any render scale value set, let us zoom out and in to see how that affects the rendered size of point symbols and labels.
We start with the map view at a scale of 1:20,000.
Press
the Zoom out button
in the main toolbar to zoom out. The view zooms out, but the size
of the symbols used for points and the size of label text does not change.
Press
the Zoom out button
again. The view zooms out, yet farther, and again the the
size of the symbols used for points and the size of label text does not
change. Point symbols have started to overlap
We
click the Back button
twice to go back to the starting 1:20,000 view. We will
now zoom in by right-clicking and dragging
a zoom box.
Zooming in for a closer view at lower scale, we see more detail in the Roads layer, but the point symbols and labels sizes have not changed.
We right-click and drag to create a zoom box and to zoom even farther in.
Zooming in farther the symbols and labels have not changed in size. They are rendered at exactly the same size no matter what the zoom scale is in use for the map window.
All of the above is typical default behavior: symbols and labels are rendered at the size specified regardless of what the zoom level is. That is very different from looking at a paper map in real life, where as we get closer to the map the symbols and labels will look bigger, because they are closer.
We now add Render Scale values to the temples and amphitheatres layers and labels.
We begin with a view using a scale of 1:20,000.
With the focus on the map window, the Layers pane shows the layers in the map. The Layers pane is still set to showing the render scale values for layers.
We double-click on the none entry for the temples layer.
That launches the Scales dialog, the same dialog that is used to set minimum and maximum scales.
We enter 20000 into the Render scale box and then press OK. If we prefer, we can enter 20,000 to use a thousands separator character for better clarity.
The value 20k appears as the render scale value for the temples layer in the Layers pane. We repeat the procedure to enter 20000 as the render scale value for the temples Labels, amphitheatres Labels, and amphitheatres layers.
Since our view is already set to a scale of 20,000, there is no visible change as a result of the render scale values we have specified.
That will change as we zoom in and out.
We begin by zooming out, to a larger scale. The point symbols and labels now are rendered smaller, just as if we were moving farther away from a printed sheet. Note that the Roads layer has not changed line width, since there is no render scale value specified for that layer.
As we continue zooming out to larger scales, the point symbols and labels keep getting smaller. If we continue zooming out to a scale ten times larger than the render scale specified, the labels will disappear since the labels will be too small to read.
Let us now see what happens when we zoom in.
We begin with a zoom level of 20,000, the same as the render scale.
As we zoom farther in to a smaller scale, the point symbols and labels will be rendered larger, just as if we were getting closer to a sheet of paper. Note that the Roads layer does not change the width of the lines, because there is no render scale value specified for the Roads layer.
As we keep zooming in, the point symbols and labels will keep getting bigger. If we zoom closer to a scale ten times smaller than the render scale value specified, the labels will disappear, since very great differences between the scale of the view and the render scale value result in absurdly large labels.
Render scale values also apply within frames in layouts. It is important to make the distinction that render scale applies within frames, because a layout overall is always rendered as if it was a sheet of paper, so that zooming an overall view of a layout in and out will cause the various elements that make up the layout to get larger and smaller, just like getting closer and farther away from a sheet of paper.
Zooming the overall layout page (that is, not within a frame) always zooms everything to true paper scale.
We
open a layout and click the Zoom to Fit
button , so the layout fills the opened window. The layout is based
on an A4 paper size, roughly equivalent to US Letter paper size, using
a landscape format.
Click the Zoom Out button
to zoom the entire view of the layout out.
The entire layout is resized and rendered smaller, as if the sheet of paper for the layout has been moved farther away.
Click
the Zoom In button to zoom the
entire view of the layout in.
When zooming in, the entire layout is resized and rendered bigger, as if the sheet of paper for the layout has been moved closer. In the view above we have also panned the layout view slightly to bring the upper left corner of the layout into view.
There is no render scale setting for layers in layouts because layouts are always rendered at true scale, as if they really were a sheet of A4 sized paper (or whatever paper size has been specified for the layout). Zooming in and out of an overall layout view alters the visual presentation of all the frames in the layout, including text frames, legends and so forth. That allows us to work with a layout as if it were a sheet of payer with the display composed of various frames that have been placed into the composition.
That is different from the use of render scale in drawings, labels, and maps that appear within frames in the layout. When we define render scale values for those components, those render scale values will also apply in any frame within which those components appear.
Consider, for example, the main frame in the layout in this example, which shows the map component that was used in this example. In the illustration below, we have turned off the text frame that showed the large Nîmes caption.
To open the frame for panning and zooming within the frame, Double-click anywhere within the frame.
A black border appears around the frame (just visible given the dark background of the map) to indicate it is now in panning and zooming mode.
Right-click and drag to draw a zoom box.
When the view within the frame is zoomed in, the point symbols and labels get bigger, just the way they do when zooming in a map window showing that map with the specified render scale settings.
One of the main reasons to use render scale is to lock the rendering of a given layer to a given scale, so that presentations can be created that use a fixed scale. If we specify a render scale value of 20,000 we should use a Location that uses a scale of 20,000 to position the view within the layout frame, so the frame is also set to a scale of 1:20,000.
Rendering labels with render scale does not render anything if the specified render scale is 10 times smaller than the current scale or 10 times bigger than the current scale. That avoids rendering labels that are far too small or too big at the window's scale.
Consider a map we have created that shows roads and road labels in Palo Alto, California. The view above has been zoomed to 1:5000 scale.
In the Layers pane we have set the Render scale value to 5,000 for both the Roads Labels and the Roads layers.
In the view above we have zoomed the map window to 1:625 scale. Both the Roads Labels and the Roads layers are rendered larger, since their render scale value pins them to a fixed 1:5000 scale.
If we keep zooming in to a 1:475 scale, the labels in the Roads Labels layer disappear, since at that scale they are too large to be useful. Note that the auto-disappearance of labels when the viewing scale is ten times larger or ten times smaller than the render scale value specified is for labels only. Symbology in drawings will not auto-disappear when the viewing scale is more than ten times larger or smaller than the render scale value set.
A zoom scale smaller than 1:500 is more than ten times smaller than the Render scale value set of 1:5000, so at any scale smaller than 1:500 the labels will disappear.
We can see the effect in the opposite direction, by starting with a view at 1:5000 scale value, as seen above, and then zooming out.
Zooming out to 1:10000 scale, both the labels in the Roads Labels layer and the vector symbology in the Roads drawing layer have become smaller.
Zooming out to 1:20000 scale, both labels and line symbology are smaller yet.
Zooming out to 1:60000 scale, the labels have disappeared, while the line symbology continues to be rendered. Ten times larger than the Render scale value of 1:5000 is a zoom scale of 1:50000, so in views with zoom scales greater than 1:50000 the labels will disappear.