Rules for Contour Lines

Contour lines are not necessarily drawn in the same location as HLR edges. Consider this model shown in Hidden Lines Removed mode:

Outside Edges of Models

Contour lines are drawn on the outside edges of a model. View orientation changes may result in different edges being drawn with contour lines. A few outside edges are highlighted by the blue arrows.

Edges Where Adjacent Faces Are at a Sharp Angle

Contour lines are drawn on edges if the normal direction of adjacent faces is greater than 89.5°. In the example, no contour lines are drawn on the edges marked with an X because the angle between the adjacent faces is not sharp enough. A contour line is drawn on the edge marked with a ! because the angle between the adjacent faces is 100°.

Edges Where Adjacent Faces Have a Different appearance

Contour lines are drawn when adjacent faces have a different appearance. This includes instances where you assign the same appearance to adjacent faces because the software creates a copy of the appearance. In the example, a different appearance was added to the face marked with an X. Now, two contour lines are added to mark the boundary between the different appearances.

Imported Geometry

Contour lines between two faces with the same orientation are not shown unless the two faces belong to different rendering objects or have different appearances or decals.

A rendering object is created for each SolidWorks feature, so contour lines are drawn between two SolidWorks features.

However, objects that are separate in SolidWorks can become a single object when imported as geometry from another format (such as IGES). In this case, no contour line is drawn.