mzucker

It's actually easy to keep the lines out -- my challenge was to try to keep them in! Just a matter of shifting thresholds around.

Cool - will check it out!

Hence the tagline on the blog: "Why do it by hand if you can code it in just quadruple the time?" :)

Pretty sure focal length would affect things as you say, but also physical dimensions matter too. My program assumes fixed focal length and then picks the page dimensions that work with the assumed focal length -- almost certainly not the correct ones.

Yep, might just work out of the box -- give it a shot!

Yep, I'm still waiting to use ceres for something - I didn't end up using it on my image approximation project https://mzucker.github.io/2016/08/01/gabor-2.html because it doesn't work well with inequality constraints.

The main rationale is removing redundant degrees of freedom -- since the page is allowed to rotate freely, the edges of the page can still move around plenty.

That sounds like a good idea and pretty straightforward to implement -- now I almost wanna try it...

Thanks for the feedback, everyone -- happy to answer questions here or in the Disqus comments on my blog.

Author here - woke up this morning and saw a big bump in site traffic which led me back to HN -- nice to see folks are reading! Happy to answer any questions here or in the Disqus comments on my blog.