the camera region dimension

I have to know the size of the area where this camera focusing?
For example I need to add labels in an area where I focus camera with zoom and zoom out when I give or move to the side taking the visibility or remove.

I’m not sure what the latest is here, but this thread could be of interest:!searchin/cesium-dev/camera$20visible$20extent/cesium-dev/ZLxOyMuA3vo/vB8uO1p3Y_oJ


The methods Cesium.Extent() and Camera.viewExtent () have been removed?

We did some renames for Cesium 1.0 so these are now Cesium.Rectangle and Camera.viewRectangle.