Rhino Preferences

This section determines which surfaces, meshes, curves, and polylines are imported.

• Surfaces - 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.

• Meshes - 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.

• Curves and Polygon Lines - 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.

This section determines what gets tessellated.

• Tessellation Quality - Sets the level of tessellation applied, with Course being the lowest tessellation and least memory intensive to High or Custom (depending on the settings) being the highest quality and most intensive.

• Chord Deviation - Sets the tolerance of the distance from the NURBS surface to the tessellated surface in mm. Lower values result in more accurate polygon models but also increase the number of triangles.

• Normal Tolerance - Sets the normal tolerance of adjacent triangles in degrees. Lower values result in more accurate polygon models but also increase the number of triangles.

• Max Chord Length - Sets the maximum length of a triangle edge in mm. Lower values result in more accurate polygon models but also increase the number of triangles.

• Enable Stitching - Enables stitching of adjacent edges.

• Stitching Tolerance - Sets the tolerance in mm where two adjacent edges are considered to be touching and where they should be stitched together.

This section determines which advanced options, like source date, normals, and unshared nodes are enabled during import.

• Keep Source Data - Sets the default behavior to keep NURBS data instead of deleting it. This option will increase memory usage. When disabled, the source data is removed during import.

• Unify Surface Normals - Sets the default behavior to ensure all surface normals point in the same direction (out or in). Merges all tessellated surfaces into one (stitched) mesh during import, when enabled. When disabled, surface normals are not changed during import.

• Merge Geometries - Sets the default behavior to merge the geometries to create one single (stitched) mesh during import, since a single shell can have many NURBS surfaces; otherwise, if disabled, you will have one mesh per surface.

• Create Groups for Layers - Sets the default behavior to create layer groups during import for items that were originally organized in layers (for example, in Autodesk Alias). Otherwise, the objects are all placed under the same parent node.

• Remove Empty Groups - Sets the default behavior to remove all empty (unnecessary) groups in your file during import.

• Unshare Nodes - Sets the default behavior for the unsharing of nodes. When enabled, shared node instances, used to save memory, are removed so that nodes exist independently. When disabled, there is no change to shared nodes during import.

• Flush Transformation - Moves the transformation data of the scenegraph hierarchy to the vertices 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.