OBJ import options

Keep Normals: Specifies whether to preserve vertex normals when files are retrieved. When this option is on ON (the default), vertex normals are retrieved from the file and used by the renderer. When this option is on OFF, vertex normals are ignored, which means that they are recalculated during rendering.

WarningIf vertex normals are retrieved, they are “frozen” and are not updated. Vertex level editing, such as moving one vertex in relation to its neighbors, can make the frozen normals invalid, so subsequent renderings will not be correct. However, object-level editing (such as translation, rotation, or proportional scaling) does not cause these problems.
Input Units: Specifies the major linear unit for the incoming file.
Scale Factor: Specifies the scaling factor for this save. The default is 1.0.
Merge Vertices: Specifies whether vertices are considered for merging.

ON (the default) – Vertices are merged if they are within the position tolerance.

OFF – Vertices are not merged.
Position Tol. (units): Specifies how close vertexes must be to be merged, in the current major linear units. The default is 0.0001 unit.