I’d like to try to fix this in our OBJ reader code so that workarounds are unnecessary, if possible.
It is true that the OBJ format doesn’t support global or local transforms for the points however some of the modeling applications will add a comment at the top that hint about the true units for the points. For example, in Maya the OBJ export window has a combo UI element where the units can be specified, however Maya will always write the actual point data in centimeters. Selecting the true units during export appears to affect the unofficial comment at the first line of the file, so I believe we can unambiguously determine the true intended units when we parse a Maya OBJ file. Dunno about whether it sometimes can insert a hint about rotation there… I’ll have to test.
I’m wondering if 3ds uses the same trick. Does it offer options during the export stage? Maybe someone here could supply me with example 3ds OBJ files of a box with dimensions <x,y,z> = <1,2,3>? If 3ds offers a transform on export then I’d like to get an OBJ of a box that was modeled Z-up <x,y,z> = <1,2,3> where the Z axis should be rotated into Y such that the box is supposed to show up with <x,y,z> = <1,3,2> (tall side up). I’d like to look at the resulting file manually to see if we can find clues in the comments.