Casting with Skewed Ejection Direction

  • Hee-Kap Ahn
  • Siu-Wing Cheng
  • Otfried Cheong
Conference paper

DOI: 10.1007/3-540-49381-6_16

Part of the Lecture Notes in Computer Science book series (LNCS, volume 1533)
Cite this paper as:
Ahn HK., Cheng SW., Cheong O. (1998) Casting with Skewed Ejection Direction. In: Chwa KY., Ibarra O.H. (eds) Algorithms and Computation. ISAAC 1998. Lecture Notes in Computer Science, vol 1533. Springer, Berlin, Heidelberg

Abstract

Casting is a manufacturing process in which liquid is poured into a cast (mould)that has a cavity with the shape of the object to be manufactured. The liquid then hardens, after which the cast is removed. We address geometric problems concerning the removal of the cast. A cast consists of two parts, one of which retracts in a given direction carrying the object with it. Afterwards, the object will be ejected from the retracted cast part. In this paper, we give necessary and sufficient conditions to test the feasibility of the cast part retraction and object ejection, where retraction and ejection directions need not be the same. For polyhedral objects, we show that the test can be performed in O(n3log n) time and the cast parts can be constructed within the same time bound. We also give a polynomial time algorithm for finding a feasible pair of retraction and ejection directions for a given polyhedral object.

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Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • Hee-Kap Ahn
    • 1
  • Siu-Wing Cheng
    • 1
  • Otfried Cheong
    • 1
  1. 1.Department of Computer ScienceHKUSTHong Kong

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