can anyone please guide me how to track a body part and render a 3d object on it???

[Prathmesh Rane]

Actually, This question deals with deep learning and augmented reality. I don't know much about deep learning. But, I want help for making a app as my engineering project which would scan the wrist of the user and when the wrist is scanned a 3d model of the a watch is perfectly occluded on the wrist of the user. Kindly help me out. I only know one thing that I need to use Unity Studio. Rest I don't know kindly help me out. 

[Terry Daniels]

Looks like you can do motion tracking right on your phone with an app by Radical Group.

https://www.youtube.com/watch?v=fwc9vTCLYCc&t=18s

If you're looking to reverse engineer some stuff you can search for stuff on Github.  I found a group called Qualysis that has a variety of different  APIs in different formats including Python and Unity which uses C#.  

https://github.com/qualisys/

Removing items from reality is a bit more sophisticated AR-type of work.  You might look into the ML image identification resources at the hub or try some sort of image sampling algorithm in Unity. Unity has some ML resources but mostly for avatar work.  

There may be some hidden layer processes in the hubs ML stuff that could work to seperate flesh from metal.  Let me know if you get to the point of removing clothing in AR.  It might be interesting! :)