LabVIEW
IMAQ Insufficient Data
Solved!
Hi aeastet,
Following example <LabVIEW>\examples\Vision\Stereo Vision\Compute Depth Image\Compute Depth Image.vi
I could make it return some internal parameter values with "Insufficient Data" = false.
I think you were overwriting the previous calibration at each iteration instead of combining all the calibration images in a single template image.
See the modified version attached.
Regards,
Raphaël.
Vision is a complex topic in itself and IMAQ makes it not always easier.
First what we do intuitively with our eyes and brain can be rather complicated to replicate with computers. Transforming our intuitive process to an algorithmic implementation is prone to many problems.
The other thing you need to remember is that an IMAQ resource very much behaves like a LabVIEW refnum. Unlike the other LabVIEW datatypes that are value based, IMAQ refnums are reference based. That can be very confusing for normal LabVIEW users. If you branch a string off and change its value in one branch you now have two different strings in memory. If you branch an IMAQ resource off and change the image content in one, your other branched off IMAQ resource will also contain the new image, since the IMAQ resource is only a reference to the actual image data.
Since images are often huge memory lumps, not treating an IMAQ resource as reference would more often than not create an out of memory error dialog, since every wire branch would create a new copy of the whole image. The IMAQ developers had the choice to try to educate the users to never branch off IMAQ wires unnecessarily or to implement an IMAQ resource as a reference, somewhat breaking the usual by value paradigm of LabVIEW wires. Guess which one felt easier to do 😀.
rolfk,
I do have one more question if you will indulge me. I have the calibration from the vi from above. I saved the calibrated image so I can use that to fix the images coming from the camera. What is the proper way to add the calibration to the raw image? I was told that this was all I need to do. Is this correct?
IMAQ Vision has in fact an even more colorful history than just 10 different developer groups. Originally it was a VI Toolkit called Concept V.I. and developed by the Aliance member Graftek. It was originally developed for LabVIEW when LabVIEW was still only running on Macintosh computers. The VI functions supported many image operations, but the VI interface was for nowadays standards a bit archaic. No error cluster, a special cluster datatype that looked like a string showing the image reference name and the rest of the data hidden. The C code behind the CINs (there were no shared libraries or DLLs back then) at that time were doubtlessly quite involved but I can only guess how much trouble it was to maintain that all, since every VI had its own CIN that required its own C code file that had to be compiled and loaded into the VI after every little change. A true maintenance nightmare.
Then in 1996 or thereabout, NI entered the vision market themselves and rather than developing their own solution, they reached an agreement with Graftek to the rights for Concept V.I. Graftek continued to do vision solutions but more or less retreated from the LabVIEW world. NI went and redesigned the Toolkit by cleaning up the C files, adding a native datatype for the IMAQ resource, integrating it with their drivers for their image acquisition hardware they were developing, and redesigning the VI interfaces to use the by now well known error cluster. The C code backend was recompiled as a single shared library that each VI could call the according function(s) from through the Call Library Node. And extensions were added to the library such as overlays, ROI and several more things.
And yes it was a bit of a stop and go project. Unlike the LabVIEW team that was a permanent group with many of its members working there for 10 and even 20 years, the vision group was a small team that developed a new feature to add to the toolkit, then the new toolkit was released and that was it for a while, with only a few technical support people remaining. Then a new feature was decided upon and everything started again. And in true software developer tradition there are always 1 more option how to architect a software than you have developers working on it, so yes paradigms changed several times. Some people were hired from other companies to integrate a new feature or product that was similar to what they had worked on before, such as the SmartCameras that were basically an idea developed in a group at Philips and when Philips decided that it was not a technology they wanted to commercialize, someone from that team went to NI and helped develop these SmartCameras.
So yes, it certainly has several different developers who were working at different times on it. And it always was a side project and not exactly a major division of its own within NI, unlike DAQ or LabVIEW, or GPIB which was still the biggest group within NI in the early 90ies.
As to your question about image calibration, I'm sorry but it has been more than 10 years that I used that function and even then only very briefly. We used overlay and the caliper function but that was about it.
