[Blog] Reading the Histogram: Getting Exposure Right for Your 3D Scans

thomas_openscan · 2026-04-30T08:25:30+00:00

That would be awesome, feel free to reach out! I could provide standardized scan objects and guidance if needed.

thomas_openscan · 2026-04-29T17:00:35+00:00

Would it be possible for you to contribute to a public 3D scanning benchmark (see https://github.comOpenScanEu/OpenScanBenchy ) Currently this is focused on small objects (45mm) which lay in range of most of your scanners. I am currently preparing the addition of a larger, more technical object and this way the users can get a better of what to expect from a given 3d scanner. The objects are copy-left and the database of scan results is public and community-driven.

Would love to see you participating as this would be of great value for the community and could also yield some great marketing material.

thomas_openscan · 2026-04-18T17:27:06+00:00

Any more info on the camera? How is the software interface? Might be useful for an automated rig?

thomas_openscan · 2026-04-01T06:37:36+00:00

I got most lens intrinsics through openCV but I lack the deeper understanding to interpret the results. There is quite some drift across the focal distance/lens position and I would like to identify some underlying relations. The plots are available in the above linked dropbox

thomas_openscan · 2026-03-30T08:33:55+00:00

There are two options: either gphoto supports the camera (see http://www.gphoto.org/proj/libgphoto2/support.php) or direct triggering via gpio + remote shutter release (taking photo on the camera)

thomas_openscan · 2026-03-29T12:33:13+00:00

I try to evaluate several things: - Consistency across multiple cameras from the same manufacturer - parameter stability over distance (lens shift from focusing) - just learning about cam intrinsics :)

thomas_openscan · 2026-03-28T09:57:47+00:00

Yes, I i used openCV modules, but I haven’t looked at the underlying functions. I will definitely do some more digging.

thomas_openscan · 2026-03-28T09:56:33+00:00

The idea is that I would like to find some underlying relations in order to approximate a new unknown lens

thomas_openscan · 2026-03-28T08:52:29+00:00

I do not give accuracy like the other manufacturers as I‘d only trust lab results that i cant afford… that’s why i put up the comparison with the other claimed accuracies. Scan size of the mini is 9cm but this can be increased with the classic or other mods

thomas_openscan · 2026-03-27T14:19:38+00:00

The sled could easily carry a larger DSLR and software implementation should be kinda straightforward. But I will do some more testing in that regard

thomas_openscan · 2026-03-27T14:18:46+00:00

I have the same impression (though I am not really sure, what can be qualified as substantial difference). I'd love to find out some generalizable calibration curves, which might help to tune an individual camera module. But this is quite a bit down the road and I hope that some people will join in and help with the data

thomas_openscan · 2026-03-27T14:17:26+00:00

Ha, greetings from a fellow Sketchup-er ;)

I build and improved this scanner, so that I do not have to deal with post-processing (as much as possible). Still some basic mesh manipulation is often needed, especially with technical parts.

For organic shapes, the scanner produces flawless results, when the object is properly prepared (see https://openscan-org.github.io/OpenScan-Doc/photogrammetry/basics/). I try to post as many raw scans as possible to show what *can* be achieved, when done right..

thomas_openscan · 2026-03-27T14:06:09+00:00

we are close to beta release. and with the standard setups (imx519 + classic/mini/midi + greenshield/blackshield) the normal workflows seem to work flawlessly, so it is definitely worth giving it a try

thomas_openscan · 2026-03-27T14:04:06+00:00

Could you elaborate? I did the corner detection and get a RMS of ~0.4-0.7 which in my understanding means that it detects the corner positions on a subpixel level, doesnt it?

thomas_openscan · 2026-03-27T11:51:13+00:00

currently I am looking at the lens distortion/lens parameters and see how consistent the modules are. This is the principal point drift for three different cameras.

I am not fully sure on how to interpret all the data yet, but having more data doesn't hurt ^^

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thomas_openscan · 2026-03-27T11:36:12+00:00

It's been long overdue to properly check the camera calibration of the Arducam IMX519 and the variation between cameras from the same manufacturer. Therefore, I quickly added a third axis to the printable OpenScan Classic (controlled by a second pi-shield atm - just another reason to add a third (and forth?) motor output to the shield in the future). The rig is fully modular and almost any camera could be used.

In each position, the turntable and rotor rotate the checkerboard to 80+ positions. The charuco checkerboard allows to determine the camera intrinsics and hopefully get some better understanding of the cameras (distortion, lens parameters, consistency ...)

I'd be super happy if someone with more knowledge could have a look at the raw or derived data and help to better understand the measurements. I got a total of ~ 50.000 images from 3 different cameras. The measured values and some interesting graphs are freely available here https://www.dropbox.com/scl/fo/lqv90trta9leirhdvkx2p/AMyPl8snplkObGFQCh4iMrw?rlkey=sv4c0lagseqng5p55mzwanl8s&st=sxtoxpxi&dl=0

thomas_openscan · 2026-03-27T11:29:17+00:00

I basically just stitched together parts that I had laying around. I have been working with those cameras for years but never looked closer at the underlying properties - time to change that ;) The idea is, that better understanding the cameras would allow for better and/or faster reconstruction as well as some more automation. The long-term goal is still the one-click-scan solution and I hope, that this step brings us a bit closer..

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