The Scale pane embedded into the status bar provides the current position of the mouse cursor within within a map, drawing, image, or labels windows.
For layouts, the Scale pane reports the scale for any active layout frame (one that has been picked with an Alt-click or enabled for panning and zooming with a double-click) that shows content from a map, drawing, image, or labels component. If the layout that contains the frame is writable, the scale for the layout frame can be changed using the Scale pane.
The Scale pane can report scale using the following display modes. Right-click onto the Scale pane to change the display mode.
Absolute |
Show scale as an absolute value, for example, 1:24000. This is the default mode. |
Pixel size |
Show scale as pixel size in coordinate system units, for example, 5 m / px. Reporting the scale of a layout frame in pixel size mode reports the number of coordinate system units per millimeter. |
View size |
Show scale as view size in coordinate system units, for example, 500 x 300 m. |
We use the example Cathedrals project that can be downloaded from the Product Downloads page for Manifold.
In the illustration above, showing a view of the great cathedral in Chartres, the Scale pane shows the scale for the active window is 1:5,000. That means that 1 cm on the screen will be approximately 5000 cm or 50 meters in the real world.
Note that given the focus in the illustration above is a Bing streets image server layer, the number of records reported by the Counts pane to the left of the Scale pane is very large. That is normal and expected, since image server layers from Bing and Google are indeed truly huge, being provided by server farms where each layer consists of billions of records in tiles.
Right-click onto the Scale pane to change the scale. We can change the scale to 1:1000.
The display instantly zooms, using the same center point, so the map window display is at an absolute scale of 1:1000. A scale of 1:1000 means that 1 cm on the screen represents a distance of 1000 cm or 10 meters in real life.
Choosing Custom when right-clicking on the Scale pane allows us to set whatever absolute scale we want. If desired, we can change the Set option to pixel view or view size and set scale using those display modes.
We can set the absolute scale to 1:2500. Press OK.
The display instantly zooms, using the same center point, so the map window display is at an absolute scale of 1:2500. A scale of 1:2500 means that 1 cm on the screen represents a distance of 2500 cm or 25 meters in real life.
The absolute scale mode format will automatically switch from 1:xxx to xxx:1 when a 1:xxx format would require an xxx value less than one. The number of decimal digits shown is automatically adjusted for readability.
For example, suppose we use the Custom choice to set a scale of 1:0.15.
The display instantly zooms, and the scale bar will show that as a scale of 6.667:1, which means that approximately 7 cm on the screen represents 1 cm in real life. The display is zoomed far, far into the display, so far into the image that a single very dark blue-green pixel in the image, probably somewhere on the roof of the cathedral, is far larger than the map window. It is not likely we will encounter that format in GIS work.
A more typical high resolution scale is seen above, a 1:200 absolute scale view of parking spaces and automobiles in a parking lot in Redlands, California. 1 cm on the screen measures 200 cm or 2 meters in real life.
Pixel size mode lets us set scale by the size of pixels in use by the display monitor.
Starting with the Cathedrals view seen at 1:2,500 scale in absolute scale mode, we right-click onto the Scale pane.
Choose Pixel Size in the menu.
The Scale pane switches to showing scale as the number of coordinate system units per pixel. The map window is in Pseudo Mercator projection, which uses meters as the coordinate system unit, so the scale is reported in the number of meters per pixel, in this case 0.661 meters per pixel.
Right-clicking on the Scale pane and choosing Custom allows us to set whatever scale we want in terms of pixel size. If desired, we can change the Set option to absolute scale or view size and set scale using those display modes.
We can set the pixel size scale to 1 meter. The dialog allows setting the horizontal pixel size, since pixels on computer monitors are the same size horizontally and vertically. Press OK.
The zoom used by the map window zooms out slightly so that each pixel is 1 meter in real life.
View size mode lets us set scale by the size of the real world shown in the window.
Right-click onto the Scale pane and choose View Size in the menu.
The Scale pane switches modes to use view size mode. It reports that the view shown in the Map window is 484 meters horizontally by 345 meters in the real world.
Right-clicking on the Scale pane and choosing Custom allows us to set whatever scale we want in terms of view size. If desired, we can change the Set option to absolute scale or pixel size and set scale using those display modes.
We can set the view size to 500 meters in the horizontal dimension. The dialog allows setting the horizontal view size, with the vertical size automatically calculated given the aspect ratio of the window in use. Press OK.
The view displayed in the Map window instantly zooms so that the width of the view in real live is 500 meters.
When the Scale pane is set to using view size mode, if we undock the Map window and resize it, as we resize the window the scale pane on the fly will report whatever is the current width and height in the real world of the window, updating the values as we resize the window.
The scale pane reports the scale for any active layout frame that shows content from a map, drawing, image, or labels component. An active frame is one that has been picked with an Alt-click or enabled for panning and zooming with a double-click. If the layout that contains the frame is writable, the scale for the layout frame can be changed using the Scale pane.
Suppose we have a layout that includes a frame which shows the map view
with absolute scale of 1:2500
as was used in the example above. The layout is shown below.
Tech tip: How did we create the frame that shows the map view? We dragged and dropped the Map window into the layout to create a frame that shows the map. We then double-clicked the frame to enable panning and zooming, which allows use of the Locations button. We used the Locations button Windows choice to match the view in the frame to that shown in the Map window as set to an absolute scale of 1:2500.
We then alt-clicked the map frame to put it into editing mode, and then we resized and repositioned the map view frame as desired. After that we added a text frame with a Chartres Cathedral caption and then we used alignment commands to resize the text frame and to line it up with the map frame.
If no frame in the layout is active, the Scale pane in the status bar does not show a scale, since we have not picked a frame and thus it does not know the frame for which it should show scale.
We make the map frame active by double-clicking it. If we preferred, we could make the frame active by alt-clicking it, which would pick it for editing.
A thicker black border appears around the frame, indicating it has been put into pan and zoom mode. The scale pane appears with a default absolute scale mode readout of 1:2,500, which makes sense because we created that frame by matching the view of the map window, which also used the same absolute scale.
We can change the scale pane mode to pixel size mode.
Right-click the scale pane and choose Pixel Size in the menu.
The scale pane immediately switches to showing the scale using pixel size mode. It reports that the scale of the image is 2.500 meters per millimeter. When the layout is printed out on paper, if we measured one centimeter (ten millimeters) in the view shown in the map frame, that would cover 25 meters of distance in real life in Chartres.
This layout is a component within the map project, so it is fully read/write. We can change the scale to a different pixel size.
Right-click on the scale pane and in the menu choose Custom to launch the Scale dialog.
If desired, we can change the Set option to absolute scale or view size and set scale using those display modes.
We set the pixel size scale to 1 meter. The dialog allows setting the horizontal pixel size, since pixels printed out on payer are the same size horizontally and vertically. Press OK.
The display immediately zooms (using the same center point) so that the view shown in the map frame is at a scale of one meter per millimeter. When we print the layout, measuring a centimeter (ten millimeters) of the image on the printed layout will cover a distance of ten meters in real life in Chartres.
Note also that an asterisk * character appears by the name of the project at the upper left of the Manifold desktop, indicating the project has been changed. When we zoom in and out of a map window, we do not change the data in a project. However, when we change a layout frame so that it uses a different view we change the project, and should save it if we want to preserve the changes.
If we like, we can add another text frame with the text Scale: 1 meter per millimeter so anybody who uses our printed layout can measure distances in the layout.
Layouts that are not writable - This topic mentions that the scale pane can be used to change the scale of the view shown in a layout frame if the layout that contains the frame is writable. Why might a layout not be writable? that can happen when we open a .map project read-only, or when we link in a .map project read-only, or when the layout is stored in a database where we only have read-only access permissions.
Approximate Scale - Scale is approximate given variations in dots per inch and screen resolutions. If the coordinate system used is Latitude / Longitude, the scale will be approximated using the latitude of the center of the data set's rectangle.
Projections Matter - Scale reported also depends on the projection (coordinate system) in use. For accurate scale measurements, use a coordinate system that provides accurate scale for the view.
Turn Scale and other Status Bar Panes on/off - Right-click onto a blank portion of the status bar to turn optional panes on or off.
The Scale pane in the status bar is on by default.
The Hero who Saved Chartres Cathedral - For notes on how Colonel Welborn Griffith gave his life to prevent the destruction of Chartres cathedral, see the Example: Locations topic.