Swept regions and surfaces: Modeling and volumetric properties

  • Authors:
  • James Damon

  • Affiliations:
  • Department of Mathematics, University of North Carolina, Chapel Hill, NC 27599-3250, USA

  • Venue:
  • Theoretical Computer Science
  • Year:
  • 2008

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Abstract

We consider ''swept regions'' @W and ''swept hypersurfaces'' B in R^n^+^1 (and especially R^3) which are a disjoint union of subspaces @W"t=@W@?@P"t or B"t=B@?@P"t obtained from a varying family of affine subspaces {@P"t:t@?@C}. We concentrate on the case where @W and B are obtained from a skeletal structure (M,U). This generalizes the Blum medial axis M of a region @W, which consists of the centers of interior spheres tangent to the boundary B at two or more points, with U denoting the vectors from the centers of the spheres to the points of tangency. We extend methods developed for skeletal structures so that they can be deduced from the properties of the individual intersections @W"t or B"t and a relative shape operator S"r"e"l, which we introduce to capture changes relative to the varying family {@P"t}. We use these results to deduce modeling properties of the global B in terms of the individual B"t, and determine volumetric properties of regions @W expressed as global integrals of functions g on @W in terms of iterated integrals over the skeletal structure of @W"t which is then integrated over the parameter space @C.