Get models from LEGO Bricktales

[Jaco van der Molen]

.obj can be viewed with the standard 3D-Viewer in Windows, I dont know how this is on mac.

The obj files that come directly from the extract do not load in the Windows obj viewer.
However if I import the obj file in Blender and export as obj again, most of them do load.
The obj files Blender makes a smaller file sizes, so I guess it takes out some data here and there?
Blender exports in Wavefront obj format and creates an .mtl file along with it. I guess this has to do something with material?
If I view the obj in the Windows viewer with the mtl file present the 3D object is rendered in a light greyish color.
If I delete the mtl file, the 3D object is rendered in a dark greyish color.