3d reconstruction and tracking

[akash02ita]

I want to obtain a 3d scan of the indoor system.
However, i am a bit unsure of how I should design the pipeline.

I am using d435i realsense to obtain pointcloud data.
What i want to achieve is to 3d scan the surroundings, especially a target object (such as forearm, or a surface, e.g. a box) so that I can do any sort of 3d drawing or projecting onto the object while tracking the 3d object as well (both the object or camera can move).

Is anyone familiar with how I should design such a pipeline/system? I currently experimented with taking multiple .ply files and applying multi-way registration but it turned out to be not effective (same code but only replaced the input .pcd files to .ply files)