On that
OGF matter, DARK TEMPLAR is right. They are three dimensional shape files. If you were to drop one of them into MAYA (or other compatible Autodesk products), provided that you have the necessary plug-in, then you'd see them in various manageable shapes/graphics, sort of graphics you'd see in CAD graphics works. In your case, GIMP plug-in is way too much faulty, unfortunately (or any of its settings, I can't comment, for don't know GIMP); as they are actually OGF files, no where near being WMF.
Well, some
DDS files do come with mipmaps, they are used to provide guided scaling of the same object in different proportions, from near view to far away, if I've managed to explain properly in correct terminology, as I'm not a graphical designer by profession. But, it's the main idea there. You may not need to deal with mipmaps for all DDS files, depends on conditions. |Just load them if they come with mipmaps and save them as they were, to be on the safe side.