prevent osm to load tiles on zoom level > 19

Question

layer_osm = new OpenLayers.Layer.OSM( "Simple OSM Map","",{
        isBaseLayer : true,
        displayInLayerSwitcher : false,
        numZoomLevels: 26,
    });

I have several WFS and WMS Layers on Top of a OSM Base Layer, and I want to stop loading the OSM layer at zoom 19, which is the max zoom for OSM. When I increase the zoom level above 19, I get 404 when loading the OSM tiles. I simply want my OSM Layer to stop loading tiles when zoom level > 19. How can I do that?

Answer 1

You can use the setOpacity function to show/hide the layer_osm by detecting the zoom level on each zoom change. For example, use the below snippet

map.events.register("zoomend", map, function(){
     var zoom = map.getZoom();
     console.log(zoom);
     if(zoom>19){
        layer_osm.setOpacity(0);
     }
     else{
        layer_osm.setOpacity(1);
     }
});

Here is a working fiddle. Zoom in the map and when you'd exceed the zoom level 19, you see that OSM layer hides while the WMS layer stays there.

Answer 2

Inside the layer parameters, define custom resolution for zoom greater than 19. As in this case i have defined the resolutions till zoom level 22.

map = new OpenLayers.Map("osm");
var layer_osm = new OpenLayers.Layer.OSM(null, null, {
        resolutions: [156543.03390625, 78271.516953125, 39135.7584765625,
                      19567.87923828125, 9783.939619140625, 4891.9698095703125,
                      2445.9849047851562, 1222.9924523925781, 611.4962261962891,
                      305.74811309814453, 152.87405654907226, 76.43702827453613,
                      38.218514137268066, 19.109257068634033, 9.554628534317017,
                      4.777314267158508, 2.388657133579254, 1.194328566789627,
                      0.5971642833948135, 0.25, 0.1, 0.05],
        serverResolutions: [156543.03390625, 78271.516953125,39135.7584765625,
                            19567.87923828125, 9783.939619140625,
                            4891.9698095703125, 2445.9849047851562,
                            1222.9924523925781, 611.4962261962891,
                            305.74811309814453, 152.87405654907226,
                            76.43702827453613, 38.218514137268066,
                            19.109257068634033, 9.554628534317017,
                            4.777314267158508, 2.388657133579254,
                            1.194328566789627, 0.5971642833948135],
        transitionEffect: 'resize'
    });
        map.addLayer(layer_osm);

the above script will result in loading the osm tiles from last zoom level (i.e. zoom 19) and show the same tiles for every zoom greater than 19.

Answer 3

Adding maxZoomLevel:19 should do the trick

layer_osm = new OpenLayers.Layer.OSM( "Simple OSM Map","",{
        isBaseLayer : true,
        displayInLayerSwitcher : false,
        maxZoomLevel: 19

    });