Abstract
Although offset surfaces are widely used in various engineering applications, their degenerating mechanism is not well known in a quantitative manner. Offset surfaces are functionally more complex than their progenitor surfaces and may degenerate even if the progenitor surfaces are regular. Self-intersections of the offsets of regular surfaces may be induced by concave regions of surface where the positive offset distance exceeds the maximum absolute value of the negative minimum principal curvature or the absolute value of the negative offset distance exceeds the maximum value of the positive maximum principal curvature. It is well known that any regular surface can be locally approximated in the neighborhood of a pointp by the explicit quadratic surface of the form r(x,y)=[x,y1/2(αx2+βy2)]T to the second order where −α and −β are the principal curvatures at pointp. Therefore investigations of the selfintersecting mechanisms of the offsets of explicit quadratic surfaces due to differential geometry properties lead to an understanding of the self-intersecting mechanisms of offsets of regular parametric surfaces. In this paper, we develop the equations of the self-intersection curves of an offset of an explicit quadratic surface. We also develop an algorithm to detect and trace a small loop of a self-intersection curve of an offset of a regular parametric surface based on our analysis of offsets of explicit quadratic surfaces. Examples illustrate our method.
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References
Faux, I. D.: Pratt, M. J. (1981) Computational Geometry for Design and Manufacture, Ellis Horwood, Chichester
Chen, Y. J.; Ravani, B. (1987) Offset surface generation and contouring in computer-aided design. Journal of Mechanisms, Transactions, and Automation in Design, ASME Transactions, 109, 3, 133–142, March
Rossignac, J. R.; Requicha, A. G. (1986) Offsetting operations in solid modelling. Computer Aided Geometric Design, 3, 2, 129–148
Patrikalakis, N. M.; Bardis, I. (1991) Localization of rational B-spline surfaces. Engineering with Computers 7, 4, 237–252
Perez-Lozano, T.; Wesley, M. A. (1979) An algorithm for planning collision-free paths amongst polyhedral obstacles. Communications of the ACM, 25 9, 560–570 October
Patrikalakis, N. M.; Prakash, P. V. (1988) Free-form plate modeling using offset surfaces. Journal of OMAE, ASME Trans., 110, 3, 287–294
Patrikalakis, N. M.; Gursoy, H. N. (1990) Shape interrogation by medial axis transform. In Proceedings of the 16th ASME Design Automation Conference: Advances in Design Automation, Computer Aided and Computational Design, Vol. I (Ravani, B. Editor), 77–88, Chicago, IL, September, New York, ASME
Wolter, F.-E. (1992) Cut locus and medial axis in global shape interrogation and representation. Computer Aided Geometric Design, 1992. Also available as MIT Ocean Engineering Design Laboratory Memorandom 92-2, January 1992
Dutta, D.; Martin, R. R.; Pratt, M. J. (1993) Cyclides in surface and solid modeling. IEEE Computer Graphics and Applications, 13 1, 53–59, January
Pham, B. (1992) Offset curves and surfaces: a brief survey. Computer Aided Design, 24, 4, 223–229, April
Lasser, D. (1988) Self-intersections of parametric surfaces. In Proceedings of Third International Conference on Engineering Graphics and Descriptive Geometry: Volume 1, Vienna, 322–331
Aomura, S.; Uehara, T. (1990) Self-intersection of an offset surface. Computer Aided Design, 22 7, 417–422, September
Maekawa, T.: Cho, W.; Patrikalakis, N. M. (1997). Computation of self-intersections of offsets of Bézier surface patches. Journal of Mechanical Design, ASME Transactions, 1997 (to appear)
Maekawa, T.; Patrikalakis, N. M. (1994) Interrogation of differential geometry properties for design and manufacture. The Visual Computer, 10 4, 216–237, March
Willmore, T. J. (1959) An Introduction to Differential Geometry, Clarendon Press, Oxford
do Carmo, P. M. (1976) Differential Geometry of Curves and Surfaces, Prentice-Hall, Englewood Cliffs, NJ
Salmon, G. (1927) A Treatise on the Analytic Geometry of Three Dimensions, Vol. 1, Chelsea, New York, 7th edition
Struik, D. J. (1950) Lectures on Classical Differential Geometry, Addison-Wesley, Reading, MA
Maekawa, T.; Wolter, F.-E.; Patrikalakis, N. M. (1996) Umbilics and lines of curvature for shape interrogation. Computer Aided Geometric Design, 13, 2, 133–161, March
Maekawa, T.; Patrikalakis, N. M. (1993) Computation of singularities and intersections of offsets of planar curves. Computer Aided Geometric Design, 10, 5, 407–429, October
Maekawa, T. (1996) Self-intersections of offsets of quadratic surfaces: Part II, implicit surfaces. Design Laboratory Memorandum 96:11, MIT, Department of Ocean Engineering, Cambridge, MA, October
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Maekawa, T. Self-intersections of offsets of quadratic surfaces: Part I, explicit surfaces. Engineering with Computers 14, 1–13 (1998). https://doi.org/10.1007/BF01198970
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DOI: https://doi.org/10.1007/BF01198970