Reference: Patch Smoothing Functions
- Last UpdatedJan 04, 2024
- 3 minute read
PACE employs three methods of defining a patch based on boundary and tangent information. One approach we will refer to as a sculpted method and give the name Sculpted #1. The other two will be collectively referred to as energy methods and are named Energy #1 and Energy #2. The sculpted and energy methods tend to be used somewhat differently. The Sculpted #1 method is the default method. It tends to produce patches that are in some way implied by the patch boundaries.
Figure 3:133. Energy method Energy#1 used to generate surface
Figure 3:134. Sculpted #1 method used to generate surface.
The Sculpted #1 surface has an associated parameter D with which the user can create a tighter or fuller surface patch. The energy methods tend to give surfaces that are tighter, a little bit like a soap bubble formed over a wire frame. One of the main advantages of the energy approach is that it gives some directional control. A patch is parameterized in two directions usually denoted as the u and v directions. It is possible to tighten the patch in one of these directions, which is useful in correcting some types of problems as depicted in the figures below.
Figure 3:135. An example of how the default surface may not be what is required
Figure 3:136. The Sculpted #1 surface is replaced by a tensioned Energy #1 one.
It is also possible to vary the amount of twist allowed in a surface. One way to look at this is to consider the parameter lines in the patch. A parameter line can be created by holding one of the parameters u or v constant while varying the other. Roughly speaking, it is possible, to a limited extent, to control the angle at which the u and v parameter lines cross, effectively controlling the stiffness of the surface.
In cases where the user already has a set of well defined ship curves the surface may be directly fitted to data points sampled from these curves without the use of a smoothing function (option (None) on the Patch Options dialogBuilding the Surface - Smoothing Page of the Patch Options Dialog).