AeroHydro,
Inc.
The most advanced 3D surface modeling available...



MultiSurf tipsOver the years we have written down and collected a
large number of tips on the use of MultiSurf, which we want to share
with the users. The tips are organized in six categories. Modeling Techniques
Tips: Viewing/Displaying
Tips:Organizing/speeding up your model
Tips: Importing files into MultiSurf
Tips: Commands
Tips: Troubleshooting/Diagnosis
Straight portions on BCurves and CCurves All of these techniques involve arranging control points that lie accurately in a straight line. To create a series of points that lie durably on a straight line,
BCurves, type 2: To make a portion straight, put at least three consecutive control points on a line; the straight portion will start and end at midpoints between control points. See PWRB2.MS2. BCurves, type 3: Put four consecutive control points on a line; the straight portion will be (approximately) between the second and third points. CCurves: The key is to put two control points very close together at the end of the straight section  for example a bead at t=0.0001 or t=0.9999. For an example, see sample file STRTPART.MS2. This method makes excellent chines and keels for powerboats. When you know the center and a start point at the correct radius, use a type3 Arc. When you know the axis and a start point at the correct radius, use a Helix with pitch=0 and angle=360 degrees. Create a Frame from three points or a
Roll/Pitch/Yaw Frame from one point and use this as a "sketching plane". Surface with a complex boundary If you are designing a surface with a complex boundary (more than four sides), first make a fair basis surface (using whichever kind of surface gives you the overall fair shape), then trim out the surface you want with a SubSurf or a TrimSurf. Use a SubSurf if the surface can be bounded by 2 snakes. A TrimSurf is best for all others Example applications: topside surface above a chine with steps; broken or stepped sheer. Often the simplest way to make a flat rectangle is with a type1 BSurf having only four
control points  the four corners. If you know three of the corners, make the fourth
as a CopyPoint from the three known corners. Suppose you have three points 'p1', 'ctr' and 'p2', and you need to construct geometry in the plane that bisects the angle 'p1''ctr''p2'. Make a type2 Arc from 'p1', 'ctr' and 'p2'. Put an AbsBead 'mid' at the center of the arc (t=0.5). Then make a Frame 3 'frame' from 'ctr', 'mid' and 'p1'. The x,z plane of 'frame' is the plane that bisects the angle; the x,y plane is the plane of the original three points. Making a copy of a surface in a new location If the copy is a mirror image of the original, use a MirrSurf. If the copy results from rotating the original about an axis, use a RotatSurf. If the copy is displaced parallel to the original, use a RelSurf with just one point (at the new location of the (0,0) corner). A CopySurf is much more versatile – the copy can have any position and location relative to the original, and can be nonuniformly scaled in the process. Build the part in a Frame, using Point objects with the Frame as their parent. When you relocate or reorient the frame, anything built from these points will go with it. Example: FRAME1.MS2 To position a bead at a given distance along a curve from either end, or from another bead, make an ArcLenBead.
The offset can be positive or negative (forward or backwards along the curve). See ARCLENBD.MS2 in Examples folder. Locating a bead at a particular X coordinate along a curve Use an XYZBead (type1 to use X as the coordinate). Wrapping an extrusion onto a surface Use a SweepSurf – "path" is a snake on the surface, "guide" is an OffsetCurv made from the snake, and "shape" is the crosssection. Examples: GUARD.MS2, GUARD1.MS2 Specifying slope at the end of a curve BCurves  Position the second control point in the desired direction from the end control point (a BCurve always ends tangent to its polyline). CCurves  You can put the second control point very close to the first, in the desired direction. The CCurve has to go through both points. XCurves  You can specify the end slopes as numerical values. If you want to specify the end slopes as angles, use a Point with Polar coordinates for the second control point.
