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SME MS920303
- Are Nurbs A Panacea?
- standard by Society of Manufacturing Engineers, 06/01/1992
- Publisher: SME
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NURBS (NON UNIFORM RATIONAL B SPLINES) HAVE MANY ADVANTAGES FOR DATA REPRESENTATION IN CAD, ESPECIALLY THEIR APPARENT UNIVERSALITY, SINCE THEY SUBSUME MOST GEOMETRIC REPRESENTATIONS AS SUBSETS, INCLUDING CONICS, BEZIER, ETC. NURBS ALSO HAVE THE ADVANTAGE OF BEING MODIFIED LOCALLY, I.E. ADJUSTING ONE PORTION OF A CURVE OR SURFACE DOES NOT NECESSARILY EFFECT ANOTHER PORTION. NURBS CAN ALSO ENSURE HIGH DEGREES OF CONTINUITY WITHIN A CURVE OR SURFACE. HOWEVER, THIS HIGH DEGREE OF FLEXIBILITY AND GENERALITY COME AT A COST: NURBS ARE SLOW AND CUMBERSOME RELATIVE TO OTHER GEOMETRIC REPRESENTATIONS. HENCE, MOST SYSTEMS HAVE IMPLEMENTED NURBS SUBSETS RATHER THAN THE GENERAL REPRESENTATION. THIS CAN LEAD TO SIGNIFICANT PROBLEMS IN EXCHANGING DATA BETWEEN THESE SYSTEMS. THESE PROBLEMS WILL BE EXPLAINED AND SOLUTIONS SUGGESTED.