Displaying Different Resolution Data Set at Different Zoom Levels

One of the greatest challenges with web maps is getting data to the user's browser and drawing it quickly. A quick approach is to provide different layers at different levels of zoom. This can be used to provide:

• Rasters of different resolutions
• Polygon and polyline layers with different levels of detail
• Point layers with different numbers of points.

As an example, you might want to create a map with cities for the globe. Displaying all the cities would take too long to draw. The easy solution is to provide several different layers, one with just the major cities, another with additional cities, and a third with all the cities. Then, set the zoom range for each layer so that the first layer is displayed when the user is zoomed all the way out. Then, set the other layers to be displayed only at certain zoom levels as the user zooms in. The CMLayer.ZOOM_RANGE property is used for this.