After tackling projection onto rectangular surfaces, the next step in this process has been to register a projection with a complex surface. In this test, I used a letter press print by Colleen Romike. The print is a pangram and contains many highly detailed shapes which provided a nice test for this process.
I took a single hand-held reference photo without paying much attention to the lighting, then did a bit of processing in photoshop to create a mask of the letters. The rest of the registration is taken care of by my projection mapping code and some simple behavioral logic to illuminate the individual letters.
The result was actually much better than I was expecting. With more attention paid to the reference photos, this process should be able to yield stunning results with very little time and effort.