Setting Up Base Layer Groups

There are two layer types--layers that contain dynamic data and base layers. Dynamic layers always reflect live and up-to-date information from underlying data sources. Base layers are pre-rendered ahead of time and stored in the cache on the server. You use base layers whose underlying data does not change very often.

You can create a set of base layers (a base layer group) to enable smooth panning and zooming in the Viewer. These layers are cached and tiled on the server so they can be quickly displayed as users move around the map. Only specified scale ranges are cached and displayed. As users zoom in or out, the cached layers at the nearest scale range are displayed.

For information on pre-scheduling the caching of base layer groups, see Scheduling and Pre-caching Tiles for Base Layers.

To set up base layer groups

1. Double-click a map to open it.
2. Click the Base Layers tab.
3. In the Base Layers For Smooth Navigation In AJAX Viewer pane, under Layers By Group And Drawing Order, click Base Layers (0 Groups, 0 Layers).
4. Click Create A New Group.

   Create as many base layer groups as you need. In the legend, users can turn the base layers groups on or off as needed. You must create at least one group and you cannot created nested groups.

5. Add layers to groups.
   Note: You can drag and drop layers from the repository tree on the left into a base layer group.

   These layers do not work as individual layers but rather as a group to provide a contextual experience for the user during pan and zoom operations.

   Do not duplicate the layers in the Layers pane. If you want to use layers as base layers, remove them from the Layers pane. You can make a base layer within a base layer group selectable.

6. Under Set Fixed Scales For Incremental Zooming, under Total Number Of Scales, enter the number of zoom scales you need.

   A set of evenly spaced scales is created. The zoom factor is indicated under Messages.

7. Specify Nearest Zoom In and Farthest Zoom Out.

   You can also adjust the map zoom in the Preview pane and click Use Current Map Zoom.