Remedy

Choosing a good set of patch boundaries is perhaps where skill and experience are most evident when using PACE. Whilst a comprehensive discussion is beyond the scope of this document, a few useful rules of thumb are:

• Wherever possible, use four-sided patches. The degenerate edge of a three-sided patch does not behave in the same way as the other corners.

• Patch shape is improved by making the pairs of opposite edges closer to being parallel. This is helped by making boundaries follow the flow of the surface shape (see Figure 3:131 below).

• Try to keep the number of patches to a minimum, whilst recognizing that a certain number of boundaries are necessary to hold the surface to the desired shape.

Figure 3:131. Example illustrating the effect of boundary curve selection on surface fairness. Here, buttocks (bottom) follow the "flow" of the surface better than sections (bottom).