| origin | 所请求观察体的原点。 |
| extents | 所请求观察体的范围（以米为单位）。 |
This method sets the observation volume as an axis aligned box at the requested location. Successive calls can be used to reshape the observation volume and/or to move it in the Scene as needed. Extents are the distance from the center of the box to its edges along each axis.
如果观察体非常大，则调用 SurfaceObserver.Update 的开销将随着可观察表面的数量增加而增加。