Using Multiple Calibration Grid Images

[Vishwarath1990]

Hi Can anyone explain how to calibrate a field of view with multiple calibration grids. I was looking at this resource but it does not detail the steps

http://zone.ni.com/reference/en-XX/help/372916L-01/nivisionconcepts/spatial_calibration_concepts/

I am working on a laser scanning algorithm and want to calibrate the ground plane on which the grids are placed. I have tried the calibration in Vision Assistant but the results are coming out wrong. Can anyone let me know of a good source for information on this

[Rscd27]

Hello Vishwarath1990,

I have a couple of comments/observations:

1-Have you consider using a bigger grid instead of three? I ask you this because the algorithm would be more complex and you could get similar results with a bigger grid.

2-The grids does not seem very well aligned on the image. Check the following screenshot:

 

This could mess up the calibration data.

3-What version of the Vision Development Module are you using? Are you using LabVIEW as well? is it 32-bit or 64-bit? The 3D calibration process is very intensive and using a 64-bit environment could be recommended. 

4-What is the purpose of doing the perspective calibration? Are you going to be doing measurements on an object?

I will investigate about how to use multiple calibration girds in one single image, I honestly have not use multiple grids at the same time except for Stereo Vision. 

Regards, 

[Vishwarath1990]

Hi Randy,

Thanks for the information. Yes, I am using LabVIEW-32 bit version and the module is NI-Vision 2015. A bigger grid does sound like a good idea. I got the current default grid out of NI vision folder, is there a location for the bigger grid you are talking about?

If we align the grids properly on the base plane would that solve the problem without a bigger one?

[Rscd27]

Hello Vishwarath1990,

I am glad that the information was useful for you. I do not believe we have a bigger grid in the NI's folder, however you can create your own grid while it cmplies with this requirements: 

What are the Requirements for an NI Vision Calibration Grid?: 

http://digital.ni.com/public.nsf/allkb/815CFD0DACE4AFB08625770F004EE84E 

For what I have read so far I believe that the way to apply the algorithm to multiple calibration grids is to apply the calibration multiple time (one by each grid). However I will confirm that for you. 

Regards,