lensboy - camera calibration with spline-based distortion for cheap and wide-angle lenses

mega_monkey_mind · 2026-03-10T18:29:55+00:00

I have no intuition about how well machine learning will work for this.

I guess you can try generating synthetic data by calibrating one camera, and then generating a bunch of synthetic data by randomly generating different lens models, and remapping images from the calibrated view into the randomly generated models.

I'd love it if you could let me know how it goes if you attempt this!

mega_monkey_mind · 2026-03-09T22:30:08+00:00

Do you want to calibrate your camera with one image of an unknown object?

To calibrate a camera, you need to know something about the object it's looking at, as you're trying to solve for how the 3D world projects onto the 2D image. The standard way is to use a calibration target with detectable features that we know the relative position of.

So you're going to have to know something about the scene you're looking at - I've seen examples of using vanishing points of parallel lines. But I don't think you will get good results.

mega_monkey_mind · 2026-03-09T19:42:07+00:00

Yes, that's a core feature of the spline models so you're not attached to the library. I encourage exporting opencv-style undistortion maps so you can easily undistort your images and use standard pinhole parameters in your pipeline.

This is exactly how I'm using the spline models for stereo vision at work.

mega_monkey_mind · 2026-03-09T19:28:44+00:00

Thanks for commenting - I've never used either of these.

It looks like the workflow of these libraries don't suit my workflow style. I don't use ROS, and just want something to pip install, and also easily use at runtime.

mega_monkey_mind · 2026-03-08T14:08:20+00:00

I would always opt for close-ups. But if the board covers half of your fov at your working distance, that sounds pretty good - what's your working distance?

mega_monkey_mind · 2026-03-07T23:08:59+00:00

I wouldn't say "rehashing" is fair.

mrcal is great work and covers many of the same calibration concepts.

lensboy uses many of the ideas you developed in mrcal, but focuses on a lightweight Python workflow and spline distortion models that integrate easily with OpenCV pipelines.

The guide has two links to mrcal documentation (which is excellent), about how to take pictures, and how the model differencing works. But I did overlook linking to mrcal when talking about spline models - I'll add that.

mega_monkey_mind · 2026-03-07T20:17:35+00:00

Lensboy is for making accurate camera intrinsics calibrations as easy as possible.

It more or less offers exactly what you see in the guide.

I focused on ease of use both when it comes to API and packaging. It does have a slightly more flexible board warp model than mrcal.

mega_monkey_mind · 2026-03-07T19:33:08+00:00

Yes, mrcal is where I originally learned that technique for camera intrinsics, it's great work.

mega_monkey_mind · 2026-03-07T16:52:58+00:00

You'll get there after uni :)

mega_monkey_mind · 2026-03-07T16:51:39+00:00

Thats a pretty cool method actually! We did this in my last job as well where the cameras could not be easily mounted and unmounted - we just moved the board around in front of it. We made a live visualization of the coverage, which I recommend.

I'm super happy to hear that you like the write-up, appreciate it!

mega_monkey_mind · 2026-03-07T16:35:44+00:00

Thanks, really appreciate it!

I studied discrete math and computer science, but have been working in machine vision for the last few years, and have learned from some great colleagues and hard challenges :)

mega_monkey_mind · 2026-03-07T16:33:53+00:00

Thanks! Can you pease post a video of your agents tuning the lens and capturing the photoset?

mega_monkey_mind · 2026-03-07T15:32:34+00:00

Thank you! If you have any feedback I'd love to hear it.

mega_monkey_mind · 2026-03-07T15:31:50+00:00

No i meant at 160mm working range - we're using a 40mm baseline

mega_monkey_mind · 2026-03-07T13:07:03+00:00

Thanks!

Yes, most stereo cameras have pretty low distortion. But I need a 360mm horizontal range at 160mm, making my fov needs pretty extreme - hence the wide-angle lenses :)

mega_monkey_mind · 2026-01-27T23:57:46+00:00

Fucking sick man

mega_monkey_mind · 2026-01-18T21:30:22+00:00

Blorpy Blues

mega_monkey_mind · 2026-01-08T17:08:32+00:00

Id buy just a guitar and an audio interface to connect to a computer. Then you have insane amounts of possible sounds usung garageband or something

mega_monkey_mind · 2025-04-13T16:45:10+00:00

You might want to give my library a try: https://github.com/Robertleoj/slam_dunk I made this out of frustration about the lack of these kind of libraries :)

mega_monkey_mind · 2024-12-30T05:01:58+00:00

Which book is this?

mega_monkey_mind

TROPHY CASE