I am trying to import some OBJ files into Poser but unfortunately they seem very diferent form the original. Some vertices even disapear when inside Poser or get mismatched forming a "very-optimized" model.

I gather by the pix that your original mesh is in 3ds format & converted to obj. It's possible that some things have gotten "lost in the translation". I've had this happen before in importing meshes. Is there any reason you can't import the original 3ds into Poser? It may handle the 3ds version better.

Poser will round the edges unless there is a second vertex close and parallel to it. Also try importing in DXF format and see the difference.

Turn off the "weld identical vertices" button when you import an obj file. (if you don't have it turned off already) Davo

Also, if you can convert to obj, UVMapper can split the vertices to give a flat appearance. This means more vertices but it stops Poser from goroud (sp?) shading the polygons. I wish poser had a shading choice in the materials dialog along with the materials. I'm still wondering if there's a flat shade material flag somewhere that's hardwired but could be changed in a script.