Kinect depth conversion from mm to pixels

问题:

Does anybody knows how many pixels correspond for each millimeter of depth value in images taken from kinect for xbox360? I'm using the standard resolution and settings...

Thanks!

回答1:

1 pixel corresponds to a number of millimiters that depends on the depth value of that pixels (i.e. its level of gray).

The simplest way you can get the distance between two pixels in a depth image is to convert those pixels (which are expressed in Depth Space) in real world coordinates (i.e. in Skeleton Space)¹. Then, you can calculate the distance between those points using a common euclidean distance formula.

So if you have two pixels P₁ and P₂, with depth values respectively equal to D₁ and D₂, you can proceed as follows:

DepthImagePoint dip1 = new DepthImagePoint();
dip1.X = P1.x;
dip1.Y = P1.y;
dip1.Depth = D1;
DepthImagePoint dip2 = new DepthImagePoint();
dip2.X = P2.x;
dip2.Y = P2.y;
dip2.Depth = D2;
SkeletonPoint sp1 = CoordinateMapper.MapDepthPointToSkeletonPoint(DepthImageFormat.Resolution640x480Fps30, dip1);
SkeletonPoint sp2 = CoordinateMapper.MapDepthPointToSkeletonPoint(DepthImageFormat.Resolution640x480Fps30, dip2);

double dist = euclideanDistance(sp1, sp2);

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¹ See Coordinate Spaces for more information.