What's new for map display and navigation in ArcGIS 10
Basemap layers are a kind of map layer that provides a framework onto which you display your dynamic operational information. Basemap display performance is very fast. Since basemap layers are relatively static and do not change frequently, their display can be computed once and reused many times. The first time you visit an area at a particular map scale, basemap layer display is computed. The display is recalled on return visits to that area and map scale.
This static nature can be advantageous enabling basemap layers to use optimized map display. For example, ArcMap can compute the map display once and then re-use it each time you pan and zoom your map.
Creating a basemap layer
First, design your basemap layers. Identify layers that are a relatively static part of your map display. Also, think about using scale-dependent drawing. This requires a map design that considers how the map is to be portrayed at each map scale.
- Once you have your map design, create each map layer in ArcMap following the normal steps.
- Add a new basemap layer to your map. Right-click the data frame name in the table of contents and click New Basemap Layer.
This adds a new basemap layer in your table of contents. The basemap layer behaves much like a group layer in that you can drag content into it.
- Select the layers that will comprise your basemap and drag them into the basemap layer.
- Rename your new basemap layer.
Once you have set this up, each time you display your map, the basemap layers are drawn using optimized map display logic. Other layers are drawn dynamically to access the latest updates from their data sources.
Basemap layers and accelerated raster layers can be used in concert with hardware acceleration to enable very high performance, continuous, smooth display as you pan and zoom your map. Turning on hardware acceleration in your ArcMap session takes advantage of your graphics card processing to further enhance performance. Hardware acceleration will not have any effect on your map if you are not using basemap or accelerated raster layers. You can turn hardware acceleration on and off on the ArcMap Options dialog box.
You can continuously pan and zoom maps that contain basemap layers and accelerated raster layers using special mouse movements as follows:
- Place the pointer anywhere in the data frame.
- Press and hold the middle mouse button or the Q key. Initially, the pointer appears as the active pan icon . After a few seconds, the pointer changes to the continuous pan cursor .
- Continue to hold down the middle button and navigate the map by dragging in the direction that you want to pan your map. The map continuously pans in that direction. As you pan, the pointer changes to an arrow pointing in the panning direction .
Press the CTRL key to speed up map panning and the SHIFT key to slow panning down.
The basemap layers pan continuously and relatively smoothly while you are panning the map. The rest of the map layers are redrawn once you release the middle mouse button.
The Scale Settings dialog box now gives you the ability to limit the scales displayed while navigating the map. It also contains presets for common Web map schemas such as ArcGIS.com, Bing Maps, and Google Maps.
Less redrawing in data view
In previous versions of ArcMap, if you changed the size of the ArcMap display while working in data view, either by resizing the ArcMap window or by docking/undocking/resizing a dockable window, by default your map was completely redrawn to fit inside the available display area. So the scale changed and the extent stayed the same (although you may have seen some extra geographic coverage based on how well the extent fit inside the new shape of the display area). At version 10, the default drawing behavior in data view has been changed so that when the display size is changed, your map is no longer completely redrawn to fit inside the display. Instead, the scale stays the same and the extent will change. If you make the display bigger, you'll see a larger geographic extent, and vice versa.
This has the performance advantage that the portion of the display unaffected by resizing doesn't need to be redrawn at all. For example, if you close a docked window, only the portion of the display that was obscured by the window needs to be redrawn. It is also easier to work with the display because geographic features on your map don't move around as you dock and undock windows. Features on your map remain in the same location in the display until you manually pan or zoom the map.
In previous releases, the Data View tab on the ArcMap Options dialog box contained an option that let you choose the redrawing behavior for your map document when the size of the display area changed. This option has been removed at 10 to ensure that all map documents opened or created in 10 benefit from the enhanced performance of the new default, irrespective of how this option was set in your map in previous versions.