STL files are generally used for purposes of rapid prototyping. A variety of methods use the STL format to construct prototypes. For example, many STL machines use a liquid polymer and harden it in small slices, creating a solid plastic model. Other STL machines use metal powder to create a model in steel. Still other machines use a special wax.
You can import and export STL files. An STL file saves object data in a format used for stereolithography. STL files have a filename extension of .stl. There is an ASCII STL format as well as a binary STL format. You can choose which to create when you export a 3D Studio scene.
The Import STL File dialog has the following options:
Name: Enter a name for the 3D Studio object created from the STL file. Default = the filename (without extension) or the name saved internally in the STL file.
Welds coincident vertices in the STL file into single vertices in the 3D Studio mesh.
Weld Threshold: Determines the size of the area which vertices must occupy to be welded. Vertices with distances equal to or less than this value are welded into a single vertex.
Weld: Turns on the Weld Vertices function. In most cases, you should leave this box selected because unwelded objects cannot be unified or smoothed.
Use Threshold: If on, STL import uses the standard 3D Studio welding method. This can be a very slow process.
Quick Weld: If on, STL import uses a welding algorithm optimized for the STL format. This is up to thirty times faster than standard 3D Studio welding, and is highly recommended.
Auto-Smooth: Applies smoothing groups to the geometry based on the smoothing angle set by the smooth angle spinner. Edges between faces that have an angle between them that is greater than the specified smoothing angle will appear faceted in the rendered image. Edges between faces that are below the specified angle are smoothed
Remove Double Faces: Removes one of the pair wherever two faces are occupying the same location. Recommended.
Unify Normals: Forces the normals of all faces on each object to face the same way (usually out). If, when you render your 3D Studio scene, the face normals are pointing in the wrong direction, use the Normal modifier to flip them. For best results, leave this box selected