When the Viewport is opened (or the Refresh button pressed), the plugin extracts geometry from the AutoCAD scene as follows:
Solids
All 3D solids are transferred into Octane, including Box, Cylinder, Sphere, Polysolid, Wedge, Cone, Pyramid, Torus and Region. All vertices and normals from these objects are transferred, however for some objects UV coordinates do not match AutoCAD in direction due to limitations in the AutoCAD API. Solids which have Nurbs curved surfaces in them may not have UV coordinates scaled correctly.
Surfaces
All surfaces should be transferred into Octane, with UV’s scaled as per Solids (i.e., scale should be correct, but the direction may not be).
Meshes
Mesh vertices are transferred into Octane, but no normal or UV information is available from the AutoCAD API, so there are no UV’s, and normals are calculated (assumes a rounded body).
Due to the way AutoCAD supplies vertex and polygon data for Polyface Mesh objects, normals are NOT calculated, so DISABLE Smoothing on all materials for these objects.
AEC Objects
These need to be converted to Solids in order to be rendered with the plugin.