distance calculation between camera and depth pixel?
The content of my research is the same as yours, but I have a problem now. I use stereocalibrate() to calibrate the binocular camera, and found that the obtained translation matrix is very different from the actual baseline distance. In addition, the parameters used in stereocalibrate() are obtained by calibrating the two cameras with calibrate().
I need to calculate distance from camera to depth image pixel. I searched through internet but I found stereo image related info and code example where I need info for depth image.
Here, I defined depth image in gray scale(0-255) and I defined a particular value( let range defined 0 pixel value is equal to 5m and 255 pixel value is equal to 500m in gray scale). 
camera's intrinsic (focal length, image sensor format) and extrinsic (rotation and transition matrix) is given. I need to calculate distance from different camera orientation and rotation. 
I want to do it using opencv python. Is there any specific documentation and code example regarding this?
Or any further info is necessary to find this.