STL and POV-ray use different coordinate systems, so the image does not look "correct".

[fizzup]

POV-ray is unusual because it uses a left-hand coordinate system. STL uses the more common right-hand coordinate system. When you print an STL on a 3D printer:

• The X axis moves the print head left-to-right (increasing X to the right).
• The Y axis moves the print bed back-and-forth (increasing Y when the print head is towards the back of the print bed).
• The Z axis moves the print head up and down (increasing Z when the print head is higher).

Due to this difference, the orientation of the image produced by POV-ray from the mesh that stl2pov creates is not the same as the plastic that you will get out of a 3D printer.

To make the image match the print, you need to store the STL Z value as the POV Y value and the STL Y value as the POV Z value. This transforms the right-hand STL coordinate system to the POV left-hand coordinate system.

[rsmith-nl]

STL uses the more common right-hand coordinate system.

Looking at the "specs" for STL files, such as they are and what there is of them, I cannot find any reference to the coordinate system used...