I'm not an expert on this, but I've seen similar questions in other areas. I don't think your problem is with the image file format, as long as poser doesn't "squawk" when you "load" it. I think it is the direction that your object faces are facing. If they face away from the camera you map to the inside of your rectangular solid and cannot see it from the outside. A quick check for this condition is to make your obj double faced with a program like Maz's TwoFace 4 which is a free download. Hope this helps :}