While the map is being built, the camera viewpoint and angle are calculated so that 3D graphics can be projected into the video stream and appear to belong in the same scene.

可视画面构建的过程中，通过相机角度的计算可以使3D画面投射到视频流中，这样，虚拟与现实物体看起来就像处在同一个场景当中。