The -q switch

• Quality mesh generation by Jim Ruppert's Delaunay refinement algorithm. (Ruppert's paper describing this algorithm is available from the Research Credit page.)
• Adds points to the mesh to ensure that no angles smaller than 20 degrees occur. Clearly, small angles between input segments cannot be eliminated; all other small angles are.
• An alternative minimum angle may be specified after the `q'. For instance, -q14.3 specifies a minimum angle of 14.3 degrees.
• If the minimum angle is 20.7 degrees or smaller, the triangulation algorithm is theoretically guaranteed to terminate (assuming infinite precision arithmetic - Triangle will fail to terminate if you run out of precision).
• In practice, the algorithm often succeeds for minimum angles up to 33.8 degrees. It usually doesn't terminate for angles above 33.9 degrees.
• For highly refined meshes, however, it may be necessary to reduce the minimum angle to well below 20 to avoid problems associated with insufficient floating-point precision.