Pilot3D uses the following types of geometry
4. NURB curves
5. NURB surfaces
The points and surfaces are separate entity types, but the lines, polylines, and curves are combined together as one entity type. This means that you can create lines, polylines, curves, or combination polyline/curves using just one input command. Pilot3D does this by assigning each edit point of a polyline or curve a special indicator value which says whether the point is a hard “knuckle” (k-type) polyline point or whether it is a smooth curve (c-type) point. The program allows you to create these shapes using the “k” and “c” key values during input. You can also switch back and forth between knuckle and curve edit points at any time after the curve has been created. This combination polyline/curve entity makes it very easy to define complicated 2D graphic arts or 3D wireframe shapes. Note that these polyline segments are not created using multiple NURB knot points or vertex points.
NURB surfaces are made up of a rectangular-like grid of rows and columns. You can create a simple surface, using the Add Surf command consisting of just two rows and two columns with 4 edit points at the intersections of the rows and columns. Then you can add more shape and flexibility to the surface by adding additional rows or columns wherever you like. Other surfaces can be constructed from curves or polylines using the extrude, sweep and loft commands.
Point entities can be used as “tick marks” or place-holders for creating complex curve and surface shapes.
Note: Pilot3D can also read mesh surfaces from DXF or IGES files and automatically fit them with one NURB surface each.