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- This file lists the set of papers and tech reports that is written using IRIT.
-
- Tech reports listed below may be ftp from ftp.technion.ac.il
- [132.68.7.8], directory pub/supported/cs/Tech_Reports/199? as
- cis????.ps.Z.
-
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- Line Illustrations $\in$ Computer Graphics
-
- Gershon Elber
-
- The revolution of the computer graphics field during the last two
- decades made it possible to create high quality synthetic images that
- even experts find it difficult to differentiate from real imagery.
-
- In this paper, we explore a partially overlooked theme of computer
- graphics that aims at conveying simple information using simple line
- drawings and illustrations of polygonal as well as freeform objects.
-
- * To appear in the Visual Computer. Also tech report CIS #9332,
- Computer Science Department, Technion, Januarry 1994
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- Proper Piecewise Linear Approximation of Freeform Surfaces.
-
- Gershon Elber
-
- We present two models for piecewise linear approximation of freeform
- surfaces. One model exploits global curvature bounds and the other
- employs an intermediate bilinear approximation. In both models, a norm
- that minimizes the maximal deviation of the piecewise linear
- approximation from the freeform surface is used.
-
- * Submitted for publication. Also tech report CIS #9413, Computer Science
- Department, Technion, October 1994
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- Symbolic and Numeric Computation in Curve Interrogation.
-
- Gershon Elber
-
- The control of shape of curves is of great importance in computer
- aided geometric design. Determination of planar curves' convexity,
- the detection of inflection points, coincident regions, and self
- intersection points, the enclosed area of a closed curve, and the
- locations of extreme curvature are important features of curves that
- can affect the design, in modeling environments.
-
- In this paper, we investigate the ability to robustly answer the above
- queries and related questions using an approach which exploits both
- symbolic computation and numeric analysis.
-
- * To appear in Computer Graphics {\it forum}. Also tech report CIS #9413,
- Computer Science Department, Technion, October 1994
-
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- Adaptive Isocurves Based Rendering: the Hardware Way.
-
- Gershon Elber
-
- In a recent work~\cite{Gershon-adap-iso-rend}, an almost optimal
- algorithm to provide a coverage based on the isoparametric curves of a
- surface was presented. This approach was combined successfully with
- curve rendering techniques and used to directly render surfaces using
- isoparametric curves instead of polygons.
-
- In this paper, we describes an adaptation of the rendering algorithm
- that uses adaptive isoparametric curves as the surface coverage, to a
- generic hardware. We also discuss the feasibility of implementing the
- adaptive isocurve extraction algorithm itself in hardware. The
- presented results make the surface coverage using adaptive extraction
- of isoparametric curves a tool for competitive freeform surface
- rendering in both software and hardware.
-
- Several results, including a videotape recording of a real time
- display, are demonstrated.
-
- * Presented in Computer Graphics International 1994 (CGI 94), Melbourne,
- Australia, June 1994.
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- Metamorphosis of Freeform Curves and Surfaces.
-
- Gershon Elber
-
- Metamorphosis between two freeform \bspline{} curves is considered and
- several approaches to control the process are discussed. Starting with
- simple convex combination, we examine two other approaches, one based
- on multiresolution decomposition of freeform curves and the other
- based on edge cutting of the control polygon of curves. The later is
- improved by introducing a correspondence test for simple metamorphosis
- relation. Finally, we consider the possibility of extending these
- algorithms to surfaces.
-
- * To appear in Computer Graphics International 1995 (CGI 95), Leeds, UK,
- June 1995.
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- Sketching as a Solid Modeling Tool
-
- Lynn Eggli, Beat Bruderlin, and Gershon Elber.
-
- This paper describes 'Quick-sketch', a 2d and 3d modeling tool for pen
- based computers. Users of this system define a model by simple pen
- strokes drawn directly on the screen of a pen-based PC. Lines,
- circles, arcs, or B-spline curves are automatically distinguished, and
- interpreted from these strokes. The system also automatically
- determines relations, such as right angles, tangencies, symmetry, and
- parallelism, from the sketch input. These relationships are then used
- to clean up the drawing by making the approximate relationships
- exact. Constraints are established to maintain the relationships in
- further editing. A constraint maintenance system, which is based on
- gestural manipulation and soft constraints, is employed in this
- system. Several techniques for sketch based definitions of 3d objects
- are provided as well, including extrusion, surface of revolution,
- ruled surfaces and sweep. Features can be sketched on the surfaces of
- 3d objects, using the same 2d- and 3d techniques. This way objects of
- medium complexity can be sketched in seconds. The system can be viewed
- as a front-end to more sophisticated modeling, rendering or animation
- environments, serving as a hand sketching tool in the preliminary
- design phase.
-
- * To appear in Solid Modeling 95, Salt Lake City, Utah, May 1995.
-