[Noble713]

Ships used in shipsets are generally created in 3d programs such as POVray, 3d Studio Max, Lightwave, etc. The files that they create contain information on 3-dimensional shapes and whatnot.

The images actually used as shipsets in the game aren't 3d files, but 2-dimensional renderings of them.

What you're trying to do is give the program a photo of an object have it re-interpret the objects in 3 dimensions, and it can't. If you want to make additions or changes to existing shipsets you will have to create new ships entirely from scratch.