Feature extraction with webar coloring

Question

I'm making a Webar Coloring with ARjs and Threejs, but how do I Feature extraction on Threejs? It bothers me..

For example, I have a car in my target map, and when I color in the target map, my car changes color. I have no idea about feature extraction right now

Does anyone do feature extraction directly on Threejs? Again, use CV

example: https://www.youtube.com/shorts/VCcUipRgDBc