[GIS] Client Zoom in OpenLayers with Google layer

google mapsopenlayers-2

I'm displaying some features on a map, but the features are somewhat on the small side and can't be easily viewed at default zoom levels. Using the Client Zoom example, I was able to enable acceptable zoom levels on an OSM layer. However, I'd like the features to be displayed on a satellite/hybrid layer.

Google is my first choice, but I have been unable to get client zoom working properly on their hybrid layer. Attempting to zoom in past the server's maximum zoom level results in the feature itself being zoomed, but not the map tile around it.

Has anyone gotten this to work? Other satellite layers would be acceptable as well.

Best Answer

Client zoom works for grid layers (OpenLayers.Layer.Grid) only. Google layers aren't grid layers. Bing layers are.

Related Solutions

[GIS] OpenLayers – Vector Layer and Google Maps – vector layer and google layers don’t seem to be in sync when zooming on Chrome

Well, I managed to figure out what was going on. Google Chrome's zoom feature doesn't respond well with OpenLayers and Google Maps. I noticed that my zoom was on 110% instead of normal 100%. As soon as you switch to 110% from 100% the 1px gap between all the tiles appears! This 1px gap will appear on some of the zoom levels. Also, the map responds more slowly at any zoom level other than 100%.

I even went to Google Maps (without OpenLayers) and the problem appears there too! The 1px gap between tiles is there. The speed doesn't take as big a hit as it would with OpenLayers, but it is still noticable.

[GIS] OpenLayers with a small, discrete set of XYZ tiles

Kromey, try this:

All tiles in OpenLayers is by default 256x256, so you don't need to explicitly declare it.
The bounds you want is in pixels, because you are dealing with an image. So the image that was split up (your original .png at 8138x5034) needs to be a perfect multiple of 256x256. Your intuition about the size being rounded up is a good one, so use that. But also, you can set your bounds higher, but you might end up pulling in status codes of 404 when OpenLayers tries to pull in tiles that are beyond your map's size.
What you are missing is resolution: 16
The magical part about maxResolution: 16 is that the map knows about it's layer via tiling -- it has no spacial reference, so resolution helps determine how big your map will be. Why 16? I don't know. I do know that resolution and maxResolution is supposed to represent units/pixel.

So, how does the code below help you?

var map; //The map
var day, night; //The layers, one for a "day" map and one for a "night" map

function init(){
  map = new OpenLayers.Map('map', {
    maxExtent: new OpenLayers.Bounds(0,0,8192,8192), //Size of the raw .png image, rounded up to a multiple of 256
    maxResolution: 16,
    resolution: 16,
    numZoomLevels: 6,

    eventListeners: {
        "zoomend": mapEvent,
        "moveend": mapEvent
    }
  });

  //Add the "day" layer
  day = new OpenLayers.Layer.XYZ("Day", "./tiles/x${x}y${y}z${z}.png");
  map.addLayer(day);

  map.zoomToMaxExtent();
}

Cheers!

Best Answer

Related Solutions

[GIS] OpenLayers – Vector Layer and Google Maps – vector layer and google layers don’t seem to be in sync when zooming on Chrome

[GIS] OpenLayers with a small, discrete set of XYZ tiles

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