dual paraboloid environment mapping


I have a problem with the dual paraboloid environment mapping method. I have successfully implemented the method with good results except for one thing.

Where the two maps meet on the object surface the seam is far from invisible. One of the two textures seems to overlap the other one, except for where the meeting takes place exactly on a vertex. I know that it should be possible to fit the two textures so that this seam disapears completely.

Does anyone have any experience in this matter? I can not find the problem myself.