I tried to initialize a cesium globe with this: url : ‘http://cesiumjs.org/tilesets/imagery/blackmarble’,
and got an error so my globe shows up as blank. How do I properly initialize it? Or is it not possible?
Same goes for default terrain..
I got mine set to use a different default imagelayer and different terrain by hacking Cesium.js
It works by removing every other imagelayer and terrain layer EXCEPT the ones that I preferred.
It thus works via an undesirable baboonTune 
The Viewer documentation covers what options are available at construction time, though we could probably use some better examples.
Here’s an example of specifying specific imagery and terrain providers. This specifies one of each and requires that the BaseLayerPicker widget be turned off.
var viewer = new Cesium.Viewer(‘cesiumContainer’, {
imageryProvider : new Cesium.TileMapServiceImageryProvider({
url : ‘//cesiumjs.org/blackmarble’,
maximumLevel : 8,
credit : ‘Black Marble imagery courtesy NASA Earth Observatory’
}),
terrainProvider : new Cesium.CesiumTerrainProvider({
url : ‘//assets.agi.com/stk-terrain/world’,
requestWaterMask : true,
requestVertexNormals : true
}),
baseLayerPicker : false
});
If you want to use the BaseLayerPicker, then you need to specify what imagery and terrain seletions are available. It’s more code bu just as straight forward. Here’s a full example that adds two possible terrains and 2 possible imagery providers. It makes the second one active by default by setting the selectedXXX properties, otherwise the first index would be active instead.
var providerViewModels = ;
providerViewModels.push(new Cesium.ProviderViewModel({
name : ‘Bing Maps Aerial’,
iconUrl : Cesium.buildModuleUrl(‘Widgets/Images/ImageryProviders/bingAerial.png’),
tooltip : ‘Bing Maps aerial imagery \nhttp://www.bing.com/maps’,
creationFunction : function() {
return new Cesium.BingMapsImageryProvider({
url : ‘//dev.virtualearth.net’,
mapStyle : Cesium.BingMapsStyle.AERIAL
});
}
}));
providerViewModels.push(new Cesium.ProviderViewModel({
name : ‘Bing Maps Aerial with Labels’,
iconUrl : Cesium.buildModuleUrl(‘Widgets/Images/ImageryProviders/bingAerialLabels.png’),
tooltip : ‘Bing Maps aerial imagery with label overlays \nhttp://www.bing.com/maps’,
creationFunction : function() {
return new Cesium.BingMapsImageryProvider({
url : ‘//dev.virtualearth.net’,
mapStyle : Cesium.BingMapsStyle.AERIAL_WITH_LABELS
});
}
}));
var terrainViewModels = ;
terrainViewModels.push(new Cesium.ProviderViewModel({
name : ‘WGS84 Ellipsoid’,
iconUrl : Cesium.buildModuleUrl(‘Widgets/Images/TerrainProviders/Ellipsoid.png’),
tooltip : ‘WGS84 standard ellipsoid, also known as EPSG:4326’,
creationFunction : function() {
return new Cesium.EllipsoidTerrainProvider();
}
}));
terrainViewModels.push(new Cesium.ProviderViewModel({
name : ‘STK World Terrain meshes’,
iconUrl : Cesium.buildModuleUrl(‘Widgets/Images/TerrainProviders/STK.png’),
tooltip : ‘High-resolution, mesh-based terrain for the entire globe. Free for use on the Internet. Closed-network options are available.\nhttp://www.agi.com’,
creationFunction : function() {
return new Cesium.CesiumTerrainProvider({
url : ‘//assets.agi.com/stk-terrain/world’,
requestWaterMask : true,
requestVertexNormals : true
});
}
}));
var viewer = new Cesium.Viewer(‘cesiumContainer’, {
imageryProviderViewModels : providerViewModels,
selectedImageryProviderViewModel : providerViewModels[1],
terrainProviderViewModels : terrainViewModels,
selectedTerrainProviderViewModel : terrainViewModels[1]
});