In the Menu Bar, click Edit > Preferences, then on the left side of the dialog box, select Import > Base CAD.
Import Options
This section determines which surfaces, meshes, curves, and polylines are imported.
Specifies which surfaces are imported. Select one of the following:
Import none - No surfaces are imported.
Import visible - Only the visible surfaces are imported.
Import all - All surfaces, regardless of whether they are visible or not, are imported.
Specifies which meshes are imported. Select one of the following:
Import none - No meshes are imported.
Import visible - Only the visible meshes are imported.
Import all - All meshes, regardless of whether they are visible or not, are imported.
Specifies which curves and polylines are imported. Select one of the following:
Import none - No curves and polylines are imported.
Import visible - Only the visible curves and polylines are imported.
Import all - All curves and polylines, regardless of whether they are visible or not, are imported.
Tesselation
This section determines what gets tessellated.
Sets the quality of the tessellation. Choose from Course, the lowest tessellation and least memory intensive, to High, which is the highest quality, yet most memory intensive. Keep in mind, there is a custom setting, which could be set to an even lower or higher tessellation quality setting.
Determines the maximum deviation between the NURBS surface and the tessellated surface. A low value results in a more accurate polygon model but also increases the number of triangles.
Determines the allowed normal deviation between the normals on the ends of a tessellated edge.
The maximum edge length of the generated polygons. Long polygon edges might not be smoothly shaded in the render view; use this setting to avoid this condition.
Enables stitching of adjacent edges.
Sets the tolerance where two adjacent edges are considered to be touching and where they should be stitched together.
Advanced Options
For advanced options, see Import Options Dialog Box.
Keeps NURBS data after tessellation instead of deleting it. This is useful for re-tessellation later, or for direct NURBS rendering, but uses more memory.
Unifies the direction of surface normals, when enabled. When disabled, no changes are made to the surface normals.
A single shell can have many NURBS surfaces. Merges the geometries to give you one single (stitched) mesh; otherwise you have one mesh per surface.
Items that are originally organized in layers (for example, in Autodesk Alias) are organized into groups. Otherwise, the objects are all placed under the same parent node.
Removes empty (unnecessary) groups.
Shared node instances, used to save system memory, are removed so that nodes exist independently.
Stores transformation data within objects themselves rather than in higher-level group nodes. In other words, if you have a hierarchy of transformation parent nodes of a geometry node, all of them are baked into one single matrix within the geometry; the original information is lost. You would want to avoid this, for example, for animating wheels on a moving car.