Reading a imported obj file in G'MIC

When I do input file.obj in G’MIC cli, it goes directly to the 3D viewer, meaning I have no context on how to read the file.

If I do echo {crop(#-1)}, I see this for a box:


What do these numbers mean?

Finally, 3d viewer doesn’t show with material to me. How do I make sure material is viewable? All I did was changed diffuse color on a detached face of a box, but nothing shows up.

This : G'MIC - GREYC's Magic for Image Computing: A Full-Featured Open-Source Framework for Image Processing - Managing 3D Vector Objects

A 3D mesh is stored as a one-column image, where all the information are stored. See link above to get the details on how data are stored.