Figure 2.

Surfel streaming in our system. An active region is defined as a sphere containing the current camera frustum. The sphere center is located at two meters from the camera. The radius of the sphere is set to eight meters. The grid timestamp is set to the latest timestamp of the surfel in the grid. The surfels in the local map are divided into equal-sized grids. The old grids far away from the current camera frustum are moved to the global map. In addition, the grids in the global map that are close to the current frame frustum are streamed back. The grids in the global map are sequentially stored according to their global positions.