Converting Kinect depth image to Real world coordinate.

edit

Hi All,

I need a small help with converting kinects depth image to the real world coordinates of each depth pixel.

I used the below mentioned formulae found from a paper. But, I assume the Z value is not the correct real world z. Rather, it gives the distance of the pixel from the camera centre. In this (x,y) on the right hand side represent the pixel values and z is the corresponding depth in meters. inv_fx,inv_fy,ox,oy are from the camera matrix.

const float inv_fx = 1.f/cameraMatrix(0,0);
const float inv_fy = 1.f/cameraMatrix(1,1);
const float ox = cameraMatrix(0,2);
const float oy = cameraMatrix(1,2);

realworld.x = z; //The depth value from the Kinect in meters
realworld.y = -(x - ox) * z * inv_fx; 
realworld.z = -(y - oy) * z * inv_fy;

If I am wrong in the formulae, plese correct the formulae mentioned above for calculating the real world point coordinates for each pixel in the depth image.

Regards, Subhasis