Pixelwise rectification in the Stereo library

[brunost]

I'm working with the Machine Vision Stereo library where I'm trying to calibrate two cameras and do some measuring of different objects. The example works fine, however as far as I can see there are no option to rectify only a single pixel coordinate from each camera. In stead, you have to rectify the whole image before you can calculate the disparity. I understand that this is the standard way to do it, but since I already have the coordinates of the pixels I want to measure, I'm wasting a lot of time/resources by rectifying the entire image. 

In other words I need either the look-up table or/and the homography matrix that IMAQ Get Rectified Image From Stereo VI uses, but as far as I can see this is information is not available. Is there perhaps a way to access the IMAQ Binocular Stereo Session, since the information most likely is hidden there?

[Klemen]

Hello,

yes I would say that the information regarding the rectification matrix for each camera must be hidden in the stereo calibration output, but I don't think this can be accessed.

At least not without knowing how NI codes this information in a file. The documentation and support regarding this is not so good in my experience.

If you want, you can use OpenCV stereo in Labview (via .dll calls). I have created both the calibration and measurement interface in Labview. The calibration also returns the rectification matrix for each camera. Take a look at this:

https://decibel.ni.com/content/blogs/kl3m3n/2015/08/28/stereo-vision-opencv-and-labview-comparison

Hope this helps in anyway.

Best regards,

K