TileMapServiceImageryProvider extent does not work

[pjcozzi]

Open the Black Marble example. Replace the addImageryProvider call with the following:

imageryLayerCollection.addImageryProvider(new Cesium.TileMapServiceImageryProvider({
    url : 'http://cesium.agi.com/blackmarble',
    maximumLevel : 8,
    extent : new Cesium.Extent(
        Cesium.Math.toRadians(-75.0),
        Cesium.Math.toRadians(28.0),
        Cesium.Math.toRadians(-67.0),
        Cesium.Math.toRadians(29.75)),
    credit : 'Black Marble imagery courtesy NASA Earth Observatory'
}));
imageryLayerCollection.addImageryProvider(new Cesium.SingleTileImageryProvider({
    url : '../images/Cesium_Logo_overlay.png',
    extent : new Cesium.Extent(
        Cesium.Math.toRadians(-75.0),
        Cesium.Math.toRadians(28.0),
        Cesium.Math.toRadians(-67.0),
        Cesium.Math.toRadians(29.75))
})); 

Run it. The Black Marble layer does not take up the same extent as the single image. As you zoom in and out, its extent changes.

[drola]

I did some research on this bug. It appears that Cesium.TileMapServiceImageryProvider.getExtent() returns proper coordinates. In less detailed zoom levels the tile is bigger than the extent which means that when extent returned by imagery provider is smaller than extent of the tile, tile should be cropped.

[kring]

Agreed, the tile should be cropped. I believe there's code to do that in place in ImageryLayer._createTileImagerySkeletons. I'd have to look into it more deeply to learn why it's not working.

[kring]

This problem only happens when the tiles on the server have a different extent from the extent specified in the constructor. It looks like the extent is used to limit which imagery tiles are associated with terrain tiles, but it is not used to limit the portion of the imagery tiles that applied to those terrain tiles.

[shunter]

I gather from @kring's comments in #970 that this is not actually fixed.

[mcecchetti]

I open a pull request: #1010