Track 3D Position of Blob/Fingertip

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Hi Foobar.Yes I want to do something like that in the paper you mentioned. I am looking for a way to accurately move a virtual object in 3D space when I do a pinch. So you take the inner contour(hole) on the border of the gap-->which are hands pixels and then calculate mass center.I want to do something like that but using as a reference the area where the 2 fingers touch each other if possible.What would you suggest.Also can you tell me more specifically what you mean by dilation?Did you find any solution for orientation?

I just drew the contour onto an image an applied cv::dilate to increase it. I found no stable solution for the orientation. A small error in the orientation will already lead to jumps in your input which is not very pleasant for the user. The same is valid for the fingertip. You need something very reliable and an error under maybe 3mm to have a good user experience.