Can Vision make absolute measurements based on pixels

[AndrewZ]

I would like to make displacement measurements of a manifold as it expands and contracts. Is there any way this can be done on an absolute pixel value basis rather than on a relative basis, compared to some other feature. This would make my life much easier.

Thank you in advance for your help,

Andrew Zwart
Wescast Test Engineering

[AndrewZ]

Sorry for being unclear in my previous post. I am trying to build such a script with Vision Builder 6.0.

Thanks,

Andrew Zwart

[nickbike]

Hello AndrewZ,
The absolute measurement you are trying to take should work exactly as you want. I am going to point you to the vision concepts document. It should be installed as a PDF document when you install NI-Vision. Pay particular attention to pages 3-7 through 3-13. This section talks about how Vision calibrates images. Your calibration to real world units can be taken into account for every measurement after you do the calibration. I am sure you have seen the example "Non-linear calibration" in the LabVIEW example finder. If not, take a look at it. With this in mind, can you please use the "IMAQ get calibration info.VI" after setting up your calibration and check the error array (not the pink cluster wire) that comes out? See if the error around the sides of the image are larger than the center of the image.

Nicholas C
National Instruments
Applications Engineering