<Li> self - intersections . </Li> <Li> noise shells . </Li> <Li> manifold errors . </Li> <P> A step in the STL generation known as "repair" fixes such problems in the original model . Generally STLs that have been produced from a model obtained through 3D scanning often have more of these errors . This is due to how 3D scanning works - as it is often by point to point acquisition, reconstruction will include errors in most cases . </P>

How many types of 3d printers are there