Ask HN: How to get large pieces of art into a digital format?

Well, if it's aside from taking a photo, there's probably nothing. It's not like you can buy a cheap scanner and rest it against a large canvas.

I worked at a cultural institution (the National Library of Australia) for many years, and the digitization section was basically just taking photographs. It was, hands down, the cheapest solution to get good quality digitizations where the source material came in many different sizes.

David Rumsey (of the map collection) seems to do this kind of thing with "big ass cameras and a lot of software" (as per @apsdsm's comment)

https://www.davidrumsey.com/about

You can pay shops with large format scanners to do it for you.

The recommendation is that you use cameras.