Brilliant, I've got them. Thanks!

23 days later

Finally got my new modern art delivered, I can finally test this again!

    That's quite large kneave ! When you are calibrating it, just make sure the board is actually flat (eg on table, or on the ground), as currently, it looks like it's bending a bit, which would cause worse calibration.
    Thanks, Erik

      Thanks Erik, I had it made to the same specifications @DanielCalaver mentioned that you use for your wide-angle products. I used it on the ground and managed to avoid the cats "helping" but sadly I'm still getting the epipolar errors.

      I'll try again tomorrow with natural light rather than the indoor lights we have and more images too.

        kneave thanks, yeah, if the board reflects too much light from ahead it can be disruptive, hope it'll work this time!

          Sadly it hasn't, though I'm down to only one epipolar error so that's progress I guess:

          Reprojection error threshold -> 100
rgb Reprojection Error: 0.688267
1200
Reprojection error threshold -> 166.66666666666666
left Reprojection Error: 0.614719
1200
Reprojection error threshold -> 166.66666666666666
right Reprojection Error: 0.577443
['high epipolar error between right and rgb']
py: DONE.

          I've uploaded the calibration images and board definition here: https://we.tl/t-5uGyFtsNkM
          The command I ran was python calibrate.py -s 4 -ms 3.1 -brd FFC-3Pw -nx 22 -ny 16 -c 3 and this is from the ar0234x3 branch of DepthAI.

          One thing I'm still unsure of which I suspect could have an impact is the HFOV value I'm using for the stereo cameras. They are the same as the centre with a 160deg lens instead of the 90 that the 0234 come with. I couldn't find a definition for the HFOV for these lenses but calculated it at 122deg, I'm not sure of my maths however as optics isn't my forte to say the least.

          I'm out of ideas and kinda annoyed I can't get this working to be honest. If you've any advice, even suggestions for other lenses to try, I'd appreciate it. Heck, if I can just calibrate with the stereo cameras and ignore the centre could that be an option? I'm planning on using the colour stereo for SLAM and point cloud generation and the centre with narrower field for object detection. If I don't actually need the centre can we get rid of that as it's the RGB to right cam that's throwing the error?

          I just ran the following to disable RGB and got the same error 🙁

          python calibrate.py -s 4 -ms 3.1 -brd FFC-3Pw -nx 22 -ny 16 -c 3 -drgb -m process

          Displaying Stereo Pair for visual inspection. Press the [ESC] key to exit.
1200
Reprojection error threshold -> 100
rgb Reprojection Error: 0.688267
1200
Reprojection error threshold -> 166.66666666666666
left Reprojection Error: 0.614719
1200
Reprojection error threshold -> 166.66666666666666
right Reprojection Error: 0.577443
['high epipolar error between right and rgb']
py: DONE.

          Yes, I downloaded the file but didn't managed to take a close look, will get back on this soon, sorry for delay @kneave

            8 days later

            Hi @kneave sorry for delay, can you check if the lenses for both LEFT and RIGHT are the same? They look a bit different for me and this might affect calibration, could you try to get some better lighting? It was a bit dark in the pictures, maybe try to put the calib board on a wall and the room to be well light? As this way, the lights from above won't be reflected.

            Hi Daniel,

            They both came off the same camera model so should be the same. I finally found the specs for hfov and they're 120 rather than 122. Not sure if that 2deg difference is enough to cause a problem.

            Will check lighting when home too, thanks for the tips!

            Keegan

            2 months later

            Hi Folks, I had to take care of some other projects and I'm just picking this back up. Could I ask if the 3xar0234 branch is still the best one to follow for multi-cam calibration please? I see there has been a new release since I looked at this last and wanted to check there isn't some kind of new Easy Mode you've added! 😅

            • erik replied to this.

              Hi kneave ,
              For calibration, I believe the modular-calibration branch (PR here) would be the best to follow, as it will also be used for calibrating OAK-D-LR (which have 3x ar0234). Thoughts?
              Thanks, Erik

                I'll have a look, thanks. Just to complicate matters I've an oak-ffc-imx378 I'm hoping to use for the centre camera now. I've not been able to get it to be detected by the 3P yet which is annoying but it's been that long since I've looked at this I've likely forgotten a trick needed. That or the one USB cable I have that works reliably has gone AWOL 😅

                  kneave is it the case that only FFC-IMX378 isn't being recognized, while other cameras are? If so, then it's not an USB issue. I would also suggest using latest depthai version.
                  Thanks, Erik

                      erik It's a bit random at the minute, it's sometimes saying no cameras detected but as it's getting that response it at least means it's connected to the 3P and able to get a response back. I'm currently printing a new enclosure, once I've got everything in place I'll do some more tests.

                      Quick render of the new enclosure attached, it'll be 3d printed so not quite as shiny! You can see the centre camera hidden in the black separator between the eyes, I'm keen to make it look like he only has two as much as possible.

                          Hi kneave ,
                          Could you copy the full terminal log of cam_test script, please? If it doesn't work as expected we will send a replacement unit. The render looks dope!! Please let us know how it will turn out🙂
                          Thanks, Erik

                            Sure thing, does it matter which branch I run cam-test from or can I install the production libraries and run against them?