Shankar Krishnan
krishnas@cs.unc.edu
http://www.cs.unc.edu/~krishnas

Education

Ph.D., University of North Carolina at Chapel Hill, February 1997 (expected)

        Title: Efficient and Accurate Boundary Evaluation Algorithms for Sculptured Solids, 
        Advisor: Dinesh Manocha

M.S., University of North Carolina at Chapel Hill, May 1993 (Computer Science).

        Title: Synthesis of Low Power Finite State Machines, 
        Advisor: Akhilesh Tyagi

B.Tech, Indian Institute of Technology, Madras, India, May 1991 (Computer Science).

Research Interests

• 3D NURBS modeling, Surface interrogation problems, Algorithmic algebra.
• Interference detection, Object simplification, Computational geometry.
• 3D computer graphics, Visibility methods.

Research and Teaching Experience

• Fall 1993 - present: Research Assistant on the modeling project (with Dr. Dinesh Manocha).
  • Design and implementation of a new robust and efficient surface-surface intersection algorithm based on a combination of algebraic and numerical techniques.
  • Design and implementation of a CSG-based sculptured solid modeling system, BOOLE, for accurate boundary representation of industrial models in walkthrough environments.
  • Studying the effect of perturbation methods on the robustness of sculptured solid modelers (joint work).
• Spring 1992 - May 1993: VLSI complexity (with Dr. Akhilesh Tyagi). Derived the lower and upper bounds on the average switching (power consumption) per transition for finite state machines. Developed a state assignment algorithm that achieves close to optimal average switching so as to minimize power consumption.
• Fall 1991 - Summer 1993: Research Assistant on Collaboratory project (with Dr. F. Donelson Smith and Dr. John B. Smith). Design and Implementation of a distributed graph server. This allows transparent sharing of objects like files and documents in a collaboratory environment (joint work).
• Summer 1995. Course Instructor for Introduction to Programming, Organized the course material, lectured, set and graded assignments, weekly tests and final exam, office hours, final grading.
• Other System Projects
  • Generation and Visualization of rims on algebraic surfaces, 1995
    Used as a teaching aid in Solid Shape course at University of North Carolina.
  • Distributed Graph and Protection Servers, 1991-93 (joint work)
    In use by the CSCW project at University of North Carolina.
  • Linda: A shared memory environment for a network of workstations, 1990-91 at IIT, Madras (joint work).
  • Design and implementation of a simulated hypercube environment for concurrent computation, 1990 at IIT, Madras.

Transfer of Technology

• My surface-surface intersection algorithm (which can essentially be used to compute any algebraic curve) is being used at a number of industrial and research locations for modeling and robotics applications.
• BOOLE (my sculptured solid modeler) is currently being integrated with the BRL-CAD system developed by the Army Research Laboratories. The BRL-CAD system is used at over a hundred sites for various modeling applications. Air Force Labs are also using the system for model building.
• Lockhead Martin Incorporated is using my modeler as part of their simulation-based design (SBD) project.

Honors and Awards

• Recipient of the National Talent Search Scholarship in India, 1985-1991.
• Fourth place in the Indian National Mathematics Olympiad, 1986.
• Second place in the All India Chemistry Talent Examination conducted by the Royal Society, London, 1985.

Refereed publications - re-prints available on request.

1. S. Krishnan and D. Manocha. An Efficient Surface Intersection Algorithm Based on Lower Dimensional Formulation. ACM Transactions on Graphics, pp. 74--106, Vol. 16, No. 1, Jan. 1997 .
2. S. Krishnan and D. Manocha. Algebraic Loop Detection and Evaluation Algorithms for Curve and Surface Interrogations. Proceedings of Graphics Interface, pp. 87-94, Toronto, Canada, May 1996.
3. S. Krishnan and D. Manocha. Numeric-Symbolic Algorithms for Evaluating One-Dimensional Algebraic Sets. Proceedings of the International Symposium on Symbolic and Algebraic Computation, pp. 59-67, July 1995.
4. S. Krishnan and D. Manocha. Computing Boolean Combinations of Solids Composed of Free-form Surfaces. Proceedings of the 1996 ASME Design for Manufacturing Conference, August 1996.
5. S. Krishnan and D. Manocha. Efficient representations and techniques for computing B-reps of CSG models with NURBS primitives. Proceedings of CSG '96 - Set-theoretic Solid Modelling: Techniques and Applications, pp. 101-122, April 1996.
6. J. Keyser, S. Krishnan, and D. Manocha. Efficient B-rep Generation of Low Degree Sculptured Solids using Exact Arithmetic. To appear in Solid Modeling '97
7. D. Manocha and S. Krishnan. Algebraic Pruning: A fast technique for curve and surface intersection. Computer-Aided Geometric Design. [To appear]
8. S. Krishnan, S. Kumar and D. Manocha. Representation, Boundary Computation and Fast Display of CSG Models with NURBS Primitives. Proceedings of the 1996 IFIP workshop, May 1996. [To Appear].
9. S. Kumar, S. Krishnan, and D. Manocha. Interactive Display of Large Solid Models for Walkthroughs. IEEE Computer Graphics and Applications, March 1996, pp 9-11.
10. S. Kumar, S. Krishnan, D. Manocha, and A. Narkhede. High Speed and High Fidelity Visualization of Complex CSG Models, Proceedings of the BCS International Conference on Visualization and Modeling, Leeds, UK, December 1995.
11. D. Manocha and S. Krishnan. Solving Zero and One Dimensional Algebraic Systems using Matrix Computations. ACM SIGSAM Bulletin , Dec. 1996, Vol. 30, No. 4, pp. 4--21.

Publications in progress

1. S. Krishnan and D. Manocha. Decomposing Spline Surfaces into Non-overlapping regions for Visible Surface Computation. [In review for International Journal of Computational Geometry and its Applications]
2. S. Krishnan, M. Gopi, D. Manocha, and M. Mine. Interactive Boundary Computation of Boolean Combinations of Sculptured Solids. [In review for Eurographics '97]

Communications, Presentations and Technical Reports

1. S. Krishnan, A. Narkhede and D. Manocha. Representation and Computation of Boolean Combinations of Sculptured Models. [communication] Proceedings of the Eleventh Annual Symposium on Computational Geometry, 1995.
2. S. Krishnan, D. Manocha and A. Narkhede. Representation and Evaluation of Boolean Combinations of NURBS Solids. Presented at the 5th MSI workshop on Computational Geometry, Stonybrook, NY, October 1995.
3. S. Krishnan, D. Manocha and A. Narkhede. BOOLE: A System to Compute Boolean Combinations of Sculptured Solids. Presented at the 4th SIAM Conference on Geometric Design Nashville, TN, November 1995.
4. S. Krishnan and D. Manocha. An Efficient Algorithm for computing the Intersection Curve of Free-Form Surfaces. Presented at the 4th SIAM Conference on Geometric Design Nashville, TN, November 1995.
5. Reviewed a number of technical papers for conferences and journals like CAGD, CVGIP.

References

• Dr. Dinesh Manocha, Assistant Professor, Dept. of Computer Science, University of North Carolina at Chapel Hill.
  Work phone: (919) 962-1749.
  E-mail address: manocha@cs.unc.edu.
  
• Prof. Frederick P. Brooks Jr., Kenan Professor, Dept. of Computer Science, University of North Carolina at Chapel Hill.
  work phone: (919) 962-1931.
  E-mail address: brooks@cs.unc.edu.
  
• Prof. Pankaj K. Agarwal, Associate Professor, Dept. of Computer Science, Duke University.
  work phone: (919) 660-6540.
  E-mail address: pankaj@cs.duke.edu.
  
• Prof. Shrawan Kumar, Professor, Dept. of Mathematics, University of North Carolina at Chapel Hill.
  Work phone: (919) 962-9615.
  Home phone: (919) 932-7151.
  E-mail address: kumar@math.unc.edu.
  
• Prof. Stephen M. Pizer, Kenan Professor, Dept. of Computer Science, University of North Carolina at Chapel Hill.
  work phone: (919) 962-1785.
  E-mail address: smp@cs.unc.edu.
  

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