So you’re viewing through the CineCameraActor in an Editor viewport? My best guess is that the aspect ratio of the CineCameraActor is different from the aspect ratio of the viewport. Cesium is using a view frustum based on one, while Unreal is rendering based on the other. Unreal unfortunately doesn’t give us very good access to this information. This often comes up in the context of actually rendering a movie with an unusual aspect ratio, and can be worked around by using the CesiumCameraManager. Details of that here: