The Visual Computer

, Volume 7, Issue 1, pp 39–58 | Cite as

Designing parametric blends: surface model and geometric correspondence

  • Pramod Koparkar


A model based on the curve-modulation technique is proposed for designing a parametric blend between two parametrically defined surfaces. The modulants are the cross section and the spine curves. The end position and tangency conditions of the cross section are discussed. Its intermediate shape can be left to the designer's choice, and generally depends on the application at hand. Various alternative choices, that fulfill the end conditions are suggested; this provides the flexibility demanded by various applications. The spine is designed as the intersection of two derived surfaces. Two alternative surface derivations are proposed, and both are discussed in some detail with their merits and demerits. The first derivation generates the contact curves automatically and relieves the designer from specifying them; the second one accepts contact curves specified by the designer, and generates the spine accordingly. Both of them are equally important in CAD/CAM and solid modelling applications.

Key words

Geometric modelling Parametric surfaces Blend surfaces Modulation technique Cross-section curves Spine curves Geometric correspondence Offset surfaces Fanout surfaces Designer-specified contact curves 


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Copyright information

© Springer-Verlag 1991

Authors and Affiliations

  • Pramod Koparkar
    • 1
  1. 1.National Center for Software TechnologyBombayIndia

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