Explains concepts and terminology used in describing curve networks.
To show the curve network toolbox, choose Surfaces > Curve Networks.
Overview
- Build a mesh of intersecting curves to describe a surface.
- Choose CrvNet Tools > New Network from the toolbox and pick all the curves.
- Alias interpolates between the curves to create surfaces automatically.
- You can continue to reshape, add or delete the construction curves, and the curve network surface will update.
- Add sculpt curves to reshape the whole curve network surface by mapping the shape of a free curve onto the surface.
Terminology
Refer to the diagram at left for illustrations of the following terms used with curve networks:
- Curve: one of the curves in the network.
- Intersection: where two curves in the network cross at the exact same point in space. In the interface this is also called
a vertex.
- Curve segment: a section of a curve defined by intersections (vertices) at both ends. Many of the curve network tools work
on curve segments, including the continuity tools. In the interface, and sometimes in this chapter, this is called an edge.
- Region: closed area of a curve network bounded by either three or four curve segments (edges).
- Curve network surfaces: the surfaces are distinct from the curve network itself. In fact, the surface can be pulled away from
the network by sculpt curves.
- Curve network: all the curves defining the surfaces. Alias will not build surfaces until all the curves in the network are valid.
Valid and invalid topology
Alias creates one surface for each valid region of the curve network.
All curve network surfaces are grouped under a single node, as shown in the Object lister or SBD window.
Under certain conditions, you may be able to create a single surface from the resulting curve network surfaces, by using the
Surfaces > Combine Surfacestool.
The following types of closed regions are valid
- Four sided regions are fitted with standard NURBS surfaces.
- Three sided regions are fitted with three NURBS surfaces.
- Regions with T-junctions that can be “collapsed” into three-, four-, or five-sided regions are treated the same as regular
three-, four-, or five-sided regions.
The following regions are not valid
- Regions with more than five sides.
- Regions with only two sides.
- Regions with T-junctions that cannot be “collapsed” into three, four, or five sided regions.
Other rules
- There can be only one curve segment between any two intersections.