Add texture to saved obj file

[felixboevr]

Hi @shubham-goel and congrats for this amazing project.

I figured out how to save the mesh as obj file according to #15

It would be great to add the texture to the saved obj file so that it can be used in blender etc. Is this possible and could you please help with the code? Thank you.

[shubham-goel]

Hi @felixboevr, it would indeed be great if we can save the texture with the mesh!!

You can use the save_obj function defined in facebookresearch/pytorch3d#332. You don't need to install the entire pytorch3d package, but this will work:

    verts_uvs = predictor.faces_uv.view(-1,2)
    if opts.texture_uvshift:
            verts_uvs[:,0] = verts_uvs[:,0] + 0.5       # u -> u+0.5
            verts_uvs = torch.where(verts_uvs>=1, verts_uvs-2, verts_uvs)
    verts_uvs[:,1] *= -1
    verts_uvs = (verts_uvs + 1)/2
    faces_uvs = torch.arange(verts_uvs.shape[0]).long().view(-1,3)
    save_obj('demo.obj', outputs['verts'][0], predictor.faces, 
            verts_uvs = verts_uvs, faces_uvs = faces_uvs, 
            texture_map = outputs['uv_image'].permute(0,2,3,1) # expected shape (1, H, W, 3)
    )

Note that we assume a spherical UV-texture map for the bird. So this will still not save perfect texture for the few faces that cross the bird's plane-of-symmetry. This will be visible as a weird artifact on the bird's back.