Time for Action – using Min and Max resolution

Let's look at how to use the minResolution and maxResolution properties and how they affect our zoom levels.

1. Instantiate your map object, by specifying the the min/max resolution properties:

   //Create a map with an empty array of controls 
   map = new OpenLayers.Map('map_element', { 
       controls: [ 
           new OpenLayers.Control.Navigation(), 
           new OpenLayers.Control.PanZoomBar(), 
           new OpenLayers.Control.LayerSwitcher() 
       ], 
       minResolution: 0.02197265625, 
       maxResolution: 0.3515625 
   });

2. You should see something like this, with limited zoom levels:

   

3. Now, let's recreate the map element and set the maxResolution and numZoomLevels properties:

   map = new OpenLayers.Map('map_element', { 
       controls: [ 
           new OpenLayers.Control.Navigation(), 
           new OpenLayers.Control.PanZoomBar(), 
           new OpenLayers.Control.LayerSwitcher() 
       ], 
       maxResolution: 0.3515625, 
       numZoomLevels:8 
   });

4. The map should now show...