Kinect：如何使用openni将深度坐标映射到世界坐标？

Question

I need to map the depth map to the world coordinates using Openni.

So I can't use any of the MSDN code such as "MapDepthToSkeletonPoint" or "MapDepthToSkeletonPoint" or "NuiTransformDepthImageToSkeleton".

I tried to use the following equations from the URL " http://www.tagwith.com/question_495583_kinect-from-color-space-to-world-coordinates " :

x = (u - principalPointX) / focalLengthX * d;
y = (z - principalPointY) / focalLengthY * d; 
z = d;

but I could not get neither principalPointX nor focalLengthX although I tried to use the method "getDepthCameraIntrinsics" but it gave me values of NaN.

I hope somebody can help with this transformation.

Answer 1

I found a solution for this problem: by getting the device handler through the OpenNIGrabber, then get the depth output mode then get the nXRes and nYRes just like the following code

depth_principal_x = ((pcl::OpenNIGrabber*)capture_)->getDevice()->getDepthOutputMode().nXRes;
depth_principal_y = ((pcl::OpenNIGrabber*)capture_)->getDevice()->getDepthOutputMode().nYRes;
focal_length= ((pcl::OpenNIGrabber*)capture_)->getDevice()->getDepthFocalLength();

Then use the following code using the assigned variables from the code above:

x = (u - depth_principal_x) / focal_length * d;
y = (z - depth_principal_y) / focal_length * d; 
z = d;

I hope this will help