Importing an OBJ File
OBJ files can be imported into FRED using the "Faceted Surface" surface type. This is done by first creating a Custom Element parent node, then adding a surface, selecting Type = "Faceted Surface."
Then, right-clicking on dialog, and selecting "Replace with data from file..."
Then, like all surfaces, optical attributes (coating, scatter, raytrace controls, materials etc.) need to be assigned.
There is no requirement that the geometry represented in the Faceted Surface represent a single object. In fact, the Faceted Surface can be used to construct an arbitrary number of individual geometry elements but will be stored in FRED's object tree as an individual surface node. Representing multiple geometry elements with a single surface node means that all of the geometry elements will have the same optical properties (coating, scatter models, raytrace controls).