zivid
Better documentation for Camera Intrinsics and Distortion parameters.
Hello, I have just stumbled into these file: https://github.com/zivid/zivid-python/blob/master/modules/zivid/camera_intrinsics.py Camera Instrinsics and Distortion parameters are quite useful for a lot of applications and should be documented better.
Best
Hi!
First of all, if you are wondering how to retrieve intrinsics from a camera, look here: https://github.com/zivid/zivid-python/blob/master/modules/zivid/experimental/calibration.py
If you are looking for documentation on how to interpret the values, then I agree it could be better. Long story short, it is the "Standard OpenCV model" intrinsics: https://docs.opencv.org/4.x/dc/dbb/tutorial_py_calibration.html
I tried to match the parameters got from Zivid calibration.py against the one I have obtained with CalibrateCamera from OpenCV and the parameter values are completely different. Are unit of measurements different somehow?
Hi Tommaso!
There should be no difference in units. The Brown distortion model uses unitless parameters that work in normalized coordinates.
Can you share the two sets of parameters for reference?
Actually, it was an issue on my side. Sorry about that. I made a small bug in the code, which resulted in wrong values.
Now my values and the ones from Zivid SDK are much closer:
Zivid:
{"_k1": -0.08929276466369629, "_k2": 0.11623617261648178, "_k3": -0.03393297642469406, "_p1": -0.0004479888884816319, "_p2": -0.00011812106822617352, "_cx": 969.7472534179688, "_cy": 592.1499633789062, "_fx": 1778.913330078125, "_fy": 1778.9261474609375}
OpenCV:
{"_k1": -0.07816818141757419, "_k2": 0.06866144436678583, "_k3": -0.024689114436057036, "_p1": 0.00016911156978288228, "_p2": -0.0004692102909033517, "_cx": 959.6700426181453, "_cy": 592.86066030548, "_fx": 1,776.7353645734295, "_fy": 1,779.8388818694884}
How are the Zivid values computed? Are these parameters uniquely computed for each Zivid camera you produce, or are they fixed for all Zivid II cameras? I am wondering whether I should trust the ones obtained from the Zivid SDK more, or the ones that I compute via calibration. Thanks!
All Zivid cameras are individually calibrated over a wide range of temperatures and aperture values with a high-end calibration process and custom algorithms. My recommendation is to trust the ones from Zivid SDK.
Thanks for this relevant info! It would make sense to add it into the documentation
Thanks for the feedback Tommaso. We'll see what we can do to improve the docs.