Like it or not, since the mid-1980s, the STL file format has been the de facto industry standard for transferring information between CAD programs and additive manufacturing equipment. However, the STL format only contains information about a surface mesh, and cannot represent color, texture, material, substructure, and other properties of a fabricated object.
As additive manufacturing technology has evolved from producing primarily single-material, homogenous shapes to producing multi-material geometries in full color with functionally graded materials and microstructures, there has been a growing need for a standard interchange file format that could support these features. A second factor that prompted the development of a new standard was the improving resolution of additive manufacturing machines. As the fidelity of printing processes approached micron scale resolution, the number of triangles required to describe smooth curved surfaces resulted in unacceptably large file sizes.
The Additive Manufacturing File Format (AMF) was introduced as an alternative to the STL file format to address many of the shortcomings of the popular file format. STL files introduce errors such as leaks and inconsistences, and also does not support color, material The choice, or orientation. STL files also rely on triangle subdivision to account for curvature. As the STL file scales in size, retaining resolution means introducing significantly more triangles. For example, a 10cm sphere at 10 micrometer resolution requires 20,000 triangles. Scaling up the 10cm sphere at the same resolution would significantly increase the amount of triangles, resulting in a much larger file. AMF seeks to address these issues by redesigning the way a 3D object is digitally stored.
