| origin | 所请求观察体的原点。 |
| radiusMeters | 所请求观察体的半径（以米为单位）。 |
This method sets the observation volume as a sphere at the requested location. Successive calls can be used to reshape the observation volume and/or to move it in the Scene as needed.
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。