To my knowledge, there is no "native" support by GNU Octave. I am not
familiar with the OFF-format  or the Obj-format ( probably).
Gabriel Peyré published some code on GitHub without license . There
is a similar code on the ML File Exchange.
Regarding the remaining issues, you might take a look at the image
package . For more detailed information, please describe your
problem in more detail, best with some code example attached.