I spent a lot of time trying to respond… so I’m just going to throw this out and hope it’s taken the right way.
This optical calibration is a lot of work and I’ve found programming within the confines of the arduino to be a pain. With doing this in my free time and other projects going on, I might be able to find time to devote to the effort if a bunch of people say, “hey, this is a great idea, but 31x15 is way too many points for me. I’d give it a shot if I if I could just do a dozen squares”. But personally, if you are going to get a pattern printed on a 4x8 banner, set up a camera and all that, you might as well run it at 3-inches on center… it’s going to cost the same and you will end up having a higher resolution error matrix. The process does take a while to run, I give you that, but it requires no user intervention once you hit start. If you have a problem with a process that takes a couple hours to run, Maslow is not for you
I hate sloppy, fixed programming as much as the next person… but making it fixed 31x15 made it easier to troubleshoot and there’s been a need for a lot of that… If someone wants to take where its at and try to make it arbitrary and variable, I’d be more than happy to support them and incorporate their changes into any work I do in the future.
Now, if a goal of asking for this was to get a process included so that you can measure error at a different pattern (and not use it for calibration, or only use it to do a curve fit) that would be much simpler to do. If you wanted to use this technique to compare different changes you make to the calibration model, sled material, etc. and you felt you needed only 12, 24, 96, whatever number of points, that would be less complex (not easy, just less complex). I’ve got a lot of things I’m working on and might be able to find time to incorporate it…
I thank @johnboiles for his efforts to put this and other work out there in a PR.