Unified 3D Material (U3M) is an open source file format for materials, developed by Browzwear and Vizoo, including physical properties data and texture image maps in a single file.
The file format includes:
U3M core file
physics.json file - calculated physics data from the FAB
You can export all materials in the U3M file format. When doing so, a Unified 3D Material Archived (U3MA) file is created: a compressed (zipped) file containing all the parts of the U3M format.
2020 May Edition (2020.2.1 Build 51188) added support for U3M version 1.1.
Import of U3M 1.0 is supported by 2019 April Edition and newer
Import of U3M 1.1 is supported by 2020 May Edition (2020.2.1 Build 51188) and newer
Export of materials as U3M is done in version 1.0 if using 2020 May Edition 2020.2.0 and older
Export of materials as U3M is done in version 1.1 if using 2020 May Edition 2020.2.1 Build 51188 and newer
PBR and Phong Shading
U3M supports PBR. U3M does not support Phong shading.
If existing materials using Phong shading are exported as U3M:
Only existing maps - diffuse, specular, and normal - are included
The PBR environment interprets the maps so as to keep the same appearance as before