Title
Pythagorean-hodograph space curves
Abstract
We investigate the properties of polynomial space curvesr(t)={x(t), y(t), z(t)} whose hodographs (derivatives) satisfy the Pythagorean conditionx′2(t)+y′2(t)+z′2(t)≡σ2(t) for some real polynomial σ(t). The algebraic structure of thecomplete set of regular Pythagorean-hodograph curves in ℝ3 is inherently more complicated than that of the corresponding set in ℝ2. We derive a characterization for allcubic Pythagoreanhodograph space curves, in terms of constraints on the Bézier control polygon, and show that such curves correspond geometrically to a family of non-circular helices. Pythagorean-hodograph space curves of higher degree exhibit greater shape flexibility (the quintics, for example, satisfy the general first-order Hermite interpolation problem in ℝ3), but they have no “simple” all-encompassing characterization. We focus on asubset of these higher-order curves that admits a straightforward constructive representation. As distinct from polynomial space curves in general, Pythagorean-hodograph space curves have the following attractive attributes: (i) the arc length of any segment can be determined exactly without numerical quadrature; and (ii) thecanal surfaces based on such curves as spines have precise rational parameterizations.
Year
DOI
Venue
1994
10.1007/BF02519035
Adv. Comput. Math.
Keywords
Field
DocType
Space curve,Pythagorean hodograph,helix,arc length,canal surface
Polygon,Family of curves,Polynomial,Mathematical analysis,Numerical integration,Arc length,PSPACE,Bézier curve,Hermite interpolation,Mathematics
Journal
Volume
Issue
Citations 
2
1
55
PageRank 
References 
Authors
5.36
7
2
Name
Order
Citations
PageRank
Rida T. Farouki11396137.40
Takis Sakkalis234734.52