Correction. I realized a number of things while driving to work. The new version doesn't export normals. They are calculated by VWD. If I export normals, I have a kind of "moiré" all over the meshes. Looking more closely, this moiré seems to be linked to triangulation. Whatever I do, i cannot make the obj exporter to triangulates the quads. When the quads are imported in VWD, half the quad has a normal colour while the other half is black. I didn't have this problem with the Carrara plugin because I was exporting triangles. So, in order to solve the issue, I have to find a way to export triangles. the "triangulate nGons" option of the obj exporter doesn't work (it seems to consider that quads are not nGons). One possibility us to rewrite an obj exporter (as I did in Carrara) or triangulate the mesh before export (or a clone of the mesh). I'll make some test and see how it goes.