The relative 3D values of six of the Rubik cube visible
corners have been manually entered in image 1 to bootstrap the
system.
Constraints of parallelism, perpendicularity and coplanarity
have been used.
Without any constraints, we obtained slanted surfaces for
objects far from the frame of reference (the Rubik
cube). Constraints of parallelism and perpendicularity helped
solve this problem.
Holes in a texture are due to a lack of view or a lack of
supporting polygon for a certain view