Remedy

The remedy to this is to amend the network of active curves:

• Loops that have more than 4 sides may be split down by the addition of extra active curves, although it is best to review the network more broadly to see whether a solution can be found that minimizes the number of patches.

• Loops that have fewer than 3 sides must be split by adding a new active curve, or reviewing the network as above.

• Sometimes loops look as if they are 4-sided when they are not. For example, a small corner may be cut off by another active curve, creating a very small side that is not immediately apparent. Also, bear in mind that the number of sides in a loop is determined by the number of intersections, so even loops that look rectangular may have more than 4 sides. Beware of intersections caused by two curves that are joined end-to-end.

• Make sure that the segment in multi-sided loops that are supposed to define a planar patch do all lie within a plane.