Selectors

• Materials: Just as in a Surface View module, this selector allows you to highlight parts of the surface separating two particular regions from each other. The two regions are specified in two additional combo boxes which are shown once the selector is activated.
  
  
• Boundary Conditions: Highlights all triangles with a particular boundary id. The boundary ids defined in the surface are listed in a separate combo box. Boundary Conditions can be modified using the Set boundary ids... option of the Surface/Edit menu.
  
  
• Patches: Highlights all triangles belonging to a particular patch of the surface. The different patches can be selected using a slider displayed right beside the selector combo box. A patch is a group of triangles separating the same two regions and having the same boundary id.
  
  
• Intersection test: Performs an intersection test and highlights intersecting triangles. The compute button actually initiates the test, while the back and forward buttons allow you to cycle through the list of intersecting faces. The total number of intersections is printed in the console window. Intersections can be repaired automatically using the Fix intersections tool from the Surface/Edit menu, or manually using the edit tools described below (edge flip, edge collapse, edge bisection, vertex movement).
  
  
• Closedness test: Performs a closedness test and highlights those triangles where the test fails. This test shouldn't be applied to surfaces with several adjacent materials for which it will falsely report closedness errors.
  
  
• Orientation test: Performs an orientation test and highlights falsely oriented triangles. You should have removed all intersections before applying this check. For simple configurations the wrong triangles are removed automatically. The number of inconsistently oriented triangles and the number of removed triangles are printed in the console window. If the automatic method could not remove all incorrect orientations, you can proceed as in the case of intersections and try to repair them manually. Important: A prerequisite for the orientation test is that the outer triangles of the surface be assigned to material Exterior. If the surface does not contain such a material or if the assignment to Exterior is not correct, the test will falsely report orientation errors. This test can be applied to surfaces with multiple adjacent materials.
  
  
• Aspect Ratio, Dihedral Angle, and Tetra Quality sort all surface triangles according to different quality measures. The aspect ratio is the ratio of the radii of the circumcircle and the incircle of a triangle. The largest aspect ratio should be below 20 (better 10). The dihedral angle is the angle between two adjacent triangles at their common edge. The smallest dihedral angle should be above 5 degrees (better 10). Tetra Quality may be useful if you want to create a tetrahedral volume mesh from the surface. For each surface triangle, the aspect ratios of the tetrahedra which will probably be created for that triangle are calculated. The largest tetrahedral aspect ratio should be below 50 (better 25). The worst triangle according to the selected quality measure is displayed, and the worst quality is printed in the console window. Using the back and forward buttons right beside the selector combo box you can cycle through all other triangles and edit the surface if necessary. In the Surface/Edit menu, there are automatic tools for improving all of the quality measures: Flip edges for the triangle aspect ratio, Fix small dihedral angles for the dihedral angle, and Fix tetra quality for the tetrahedron quality.
  
  
• Non-manifold test: This test detects non-manifolds on surfaces and displays every non-manifold location including the incident triangles.
  
  
• Holes test: This test detects holes on triangular meshes, which can be closed by the triangulators available from the Fill Hole... menu entry.