Adding to basic photo pixel mapping techniques, one way to map more complex things that don’t lie flat is to take multiple photos from different angles, like front + back, and then use a photo editor to arrange them into a single image. Doing that side-by-side would give you something close to a cylindrical wrap. That might be especially handy if your wiring crosses between the front and back too.
The tricky part of this is you have to be able to see each LED in the photo (or make a decent guess), and click them in order.
You can see a good example of that in this project: