Activate this option when you want to retain the Smoothing Groups information in the imported FBX file. When the FBX file contains no Smoothing Group data and this option is activated, the plug-in re-evaluates the geometry and creates Smoothing Groups for all imported geometry based on the explicit normals data.
Activating this option directly affects performance. This performance loss occurs because the plug-in must re-evaluate all the geometry.
You can use this option when you import Revit-exported or MotionBuilder-saved FBX scenes, as they contain no Smoothing Group information, but some Smoothing Groups may not generate properly, and could potentially cause shading inconsistencies.
This option is disabled by default in the Autodesk Media & Entertainment preset. It is also disabled in the Autodesk Architectural (Revit) preset.
If the FBX scene already contains Smoothing Group data and this option is disabled, the 3ds Max FBX plug-in imports only explicit normals data (and ignores all Smoothing Group information).
There is a limitation that involves explicit normals and Smoothing Groups. See Importing Explicit normals and Smoothing Groups for an explanation.
Activating this option is ideal for 3ds Max users who import scenes intending to use and modify Smoothing Groups information.
If your scene contains thousands of objects and you know that you do not want to work with Smoothing Groups, do not use this option. Otherwise the 3ds Max FBX plug-in must re-evaluate every object during import, which is time consuming.
If you are a Maya user, the plug-in already exports smoothing information (Hard/Soft edges). Activating this option usually gives the same visual results as disabling the option. The difference is the additional Smoothing Group information/IDs (for example, faces identified as belonging to Smoothing Group 1, 2, and so on).
For example, if you want to edit the smoothing of objects that come from Revit, activate this option to create Smoothing Groups when you import. You can then edit these Smoothing Groups in 3ds Max.
Since Revit has no Smoothing Group data to export, the 3ds Max FBX plug-in importer must create it. Similarly, Maya also does not export Smoothing Group data by default. Maya uses Hard/Soft edge information that it directly applies to geometry normals, unless you activate the Maya FBX Exporter Plug-in Smoothing Group option, and then Smoothing Groups are generated from Hard/Soft edge information.
The Smoothing Groups option in the FBX Collada importer does not import Smoothing Groups from the FBX file. Instead, when you activate this option, the Importer creates the Smoothing Groups during the import process. The Collada importer must create Smoothing Groups on Import because the FBX Collada exporter does not export Smoothing Groups data from 3ds Max. If you disable the Smoothing Groups option, no Smoothing Groups are generated by the Importer.
