Autodesk 12812-051462-9011 User Guide 3 - Page 1929

NOTE Previous versions of 3ds Max supported multiple materials for polymeshes but only one material ID for each ACIS solid when importing a DWG file, regardless of how many material IDs had been assigned to the solid. NOTE Legacy AutoCAD DWG import does not support multiple materials on ACIS solids. Process When 3ds Max imports a DWG file from AutoCAD or Revit Architecture (version 2008 and later) with either the Layer, Blocks as Node Hierarchy, Split by Material" or the Entity, Blocks as Node Hierarchy derivation methods, multiple material IDs are readable and editable as Multi/Sub-Object materials in the Material Editor. 3ds Max reads each face of an imported AutoCAD/Revit solid to determine if it contains any material IDs that can be imported. If the program reads more than one material ID from a solid, it translates each material ID on import and re-assigns it to the object. The program creates Multi/Sub-Object materials only if it finds more than one material ID; if an ACIS solid contains only one material ID, 3ds Max creates and assigns a standard/architectural material instead. NOTE 3ds Max first evaluates the imported file to find any Revit material IDs, and then looks for AutoCAD material IDs. NOTE If you import a DWG file with the Layer, Blocks as Node Hierarchy, Split by Materials derivation method, it does not split the solid to reflect its materials set. Multi/Sub-Object Material Naming In earlier versions, 3ds Max read the material ID information from the color ID of the AutoCAD/Revit material ID's face. Now, it creates a Multi/Sub object material for every translated per face material ID each time you import a DWG file that contains an AutoCAD/Revit solid. When the program finds multiple materials assigned to an ACIS solid and creates a Multi/Sub-Object material, the Multi/Sub-Object material consists of instances of standard architectural scene materials. 7184 | Chapter 23 Managing Scenes and Projects