STL, abbreviation for stereolithrography, is an interchangeable file format that represents 3-dimensional surface geometry. The file format finds its usage in several fields such as rapid prototyping, 3D printing and computer-aided manufacturing. It represents a surface as a series of small triangles, known as facets, where each facet is described by a perpendicular direction and three points representing the vertices of the triangle.
OBJ files are used by wavefront's advanced visualizer application to define and store the geometric objects. Backward and forward transmission of geometric data is made possible through OBJ files. Both polygonal geometry like points, lines, texture vertices, faces and free-form geometry (curves and surfaces) are supported by OBJ format. This format does not support animation or information related to light and position of scenes.