We're building SW surfaces from the ID firm's Alias surfaces. I notice that many of the splines from Alias are not just curvature continuous, but that the curvature changes smoothly. I'm having a heck of a time trying to match that characteristic with SW04.
Checking the curvature combs, several of the splines look exactly like straight lines and radius sections joined by short splines. If I simplify the original spline I get smooth curvature, but it has reverse curvature areas where the straight and arced sections join the short splines and areas where the curvature is quite different from the original.
If I try to build my own curve with straight lines, radii and splines, I can't seem to get the splines to smoothly transition to no curvature straight lines and small curvature radii. Two point splines don't match the original spline and the curvature is discontinous at the ends. Three points splines can match the spline fairly well but also have discontinuous curvature. With four point splines I can get close enough to continuous curvature, but the transition isn't smooth. Adding more points, I don't seem to be able to make the transition any smoother.
I seem to get the closest by making my own single spline by placing a pair of points very close to the ends of the "straight" and "radii" sections and two or three points in the short spline sections, but I always seem to get wobbles in my curvature comb that I can't get rid of. Any rules of thumb on how to place my spline points?
Should I worry about making the splines curvature smooth? Is this a characteristic that the eye even notices?
Jerry Steiger Tripod Data Systems "take the garbage out, dear"