Papers by Richard Riesenfeld
Researchers at the University of North Carolina at Chapel Hill and the University of Utah partici... more Researchers at the University of North Carolina at Chapel Hill and the University of Utah participated in a collaborative, remote, rapid design and manufacturing experiment. Several domain experts at widely distributed geographical locations worked on a challenging multi-disciplinary design problem producing a rugged, compact and light-weight housing for a Video See- Through Head-Mounted Display to be used in image-guided surgical
Eurographics Symposium on Rendering/Eurographics Workshop on Rendering Techniques, 2000
Methods for exact computation of irradiance and form factors associ- ated with polygonal objects ... more Methods for exact computation of irradiance and form factors associ- ated with polygonal objects have ultimately relied on a formula for a differential area to polygon form factor attributed to Lambert. This paper presents an alter- native, an analytical expression based on vertex behavior rather than the edges the polygon. Using this formulation, irradiance values in a scene consisting of
Storage and Retrieval for Image and Video Databases, 2000
ABSTRACT
Proceedings of the 26th annual conference on Computer graphics and interactive techniques - SIGGRAPH '99, 1999
We present a solution to the general problem of characterizing shadows in scenes involving a unif... more We present a solution to the general problem of characterizing shadows in scenes involving a uniform polygonal area emitter and a polygonal occluder in arbitrary position by manifesting shadow irradiance as a spline function. Studying generalized prism-like constructions generated by the emitter and the occluder in a fourdimensional (shadow) space reveals a simpler intrinsic structure of the shadow as compared to the more complicated 2D projection onto a receiver. A closed form expression for the spline shadow irradiance function is derived by twice applying Stokes' theorem to reduce an evaluation over a 4D domain to an explicit formula involving only 2D faces on the receiver, derived from the scene geometry. This leads to a straightforward computational algorithm and an interactive implementation. Moreover, this approach can be extended to scenes involving multiple emitters and occluders, as well as curved emitters, occluders, and receivers. Spline functions are constructed from these prism-like objects. We call them generalized polyhedral splines because they extend the classical polyhedral splines to include curved boundaries and a density function. The approach can be applied to more general problems such as some of those occurring in radiosity, and other related topics.
Computer Graphics and Image Processing, 1980
Fan charts are a popular method for displaying family trees in a compact way. We extend the conce... more Fan charts are a popular method for displaying family trees in a compact way. We extend the concept of fan charts to include a number of interactive metaphors, thus transforming what was a static display medium into an interactive tool for browsing and editing genealogical data.
Computer Methods in Applied Mechanics and Engineering, 2015
ABSTRACT We present a critical analysis of the effectiveness of the current field of CAD, and dis... more ABSTRACT We present a critical analysis of the effectiveness of the current field of CAD, and discuss some of the forces that have taken it so far off course from its strikingly foresighted origins. Armed with the ensuing understanding of the operational forces that have taken CAD adrift, we conclude that the disparity between CAD’s mired state-of-the-art condition relative to more appropriate, inspired and achievable goals for CAD calls for more drastic measures. It is asserted that, well beyond the evolutionary progression of incremental steps characteristic of next version system releases, the field is overdue for developing a class of genuine design-centric, ab initio, CAD systems architectures effecting the original CAD vision through the powerful instruments of contemporary computing tools and technologies.
Lecture Notes in Computer Science, 2006
This paper presents the mathematical framework, and develops algorithms accordingly, to continuou... more This paper presents the mathematical framework, and develops algorithms accordingly, to continuously and robustly track the intersection curves of two deforming parametric surfaces, with the deformation represented as generalized offset vector fields. The set of intersection curves of 2 deforming surfaces, over all time, is formulated as an implicit 2-manifold I in the augmented (by time domain) parametric space R 5 . Hyper-planes corresponding to some fixed time instants may touch I at some isolated transition points, which delineate transition events, i.e., the topological changes to the intersection curves. These transition points are the 0-dimensional solution to a rational system of 5 constraints in 5 variables, and can be computed efficiently and robustly with a rational constraint solver using subdivision and hyper tangent bounding cones. The actual transition events are computed by contouring the local osculating paraboloids. Away from any transition points, the intersection curves do not change topology and evolve according to a simple evolution vector field that is constructed in the Euclidean space where the surfaces are embedded.
IEEE International Conference on Shape Modeling and Applications 2006 (SMI'06), 2006
Symbolic computation of NURBS plays an important role in many areas of NURBS-based geometric comp... more Symbolic computation of NURBS plays an important role in many areas of NURBS-based geometric computation and design. However, any nontrivial symbolic computation, especially when rational B-splines are involved, would typically result in B-splines with high degrees. In this paper we develop degree reduction strategies for NURBS symbolic computation on curves. The specific topics we consider include zero curvatures and critical curvatures of plane curves, various ruled surfaces related to space curves, and point/curve bisectors and curve/curve bisectors.
Computer Aided Geometric Design, 1974
International Journal of Shape Modeling, 2007
XIANMING CHEN School of Computing, University of Utah, 50 S. Central Campus Dr. Rm. 3190 Salt Lak... more XIANMING CHEN School of Computing, University of Utah, 50 S. Central Campus Dr. Rm. 3190 Salt Lake City, UT 84112, USA [email protected] http://<www.cs.utah.edu/∼xchen> ... RICHARD F. RIESENFELD School of Computing, University of Utah, 50 S. Central Campus Dr. Rm. ...
Proceedings of the 2007 ACM symposium on Solid and physical modeling - SPM '07, 2007
B-spline multiplication, that is, finding the coefficients of the product B-spline of two given B... more B-spline multiplication, that is, finding the coefficients of the product B-spline of two given B-splines, is useful as an end result, in addition to being an important prerequisite component to many other symbolic computation operations on B-splines. Algorithms for B-spline multiplication standardly use indirect approaches such as nodal interpolation or computing the product of each set of polynomial pieces using various bases. The original direct approach is complicated. B-spline blossoming provides another direct approach that can be straightforwardly translated from mathematical equation to implementation; however, the algorithm does not scale well with degree or dimension of the subject tensor product B-splines. We present the Sliding Windows Algorithm (SWA), a new blossoming based algorithm for B-spline multiplication that addresses the difficulties mentioned heretofore.
ACM SIGGRAPH Computer Graphics, 1983
ABSTRACT An abstract is not available.
ACM SIGCSE Bulletin, 2009
Many courses on the history of computing are designed for a general student audience, and as such... more Many courses on the history of computing are designed for a general student audience, and as such, include fewer technical details than one might find in a typical CS course. While this approach is appropriate in some contexts, it risks losing the interest of the students who could perhaps benefit most from the subject -namely, future computer scientists. This paper describes a technically-oriented History of Computing course which we taught at the University of Utah in 2008. Like other History of Computing courses, ours included a significant amount of writing and discussion. However, inasmuch as our course was created specifically for CS students, we also incorporated several "hands-on" programming exercises and demonstrations, giving students actual experience with the computing environments of the past. Students and faculty alike have responded enthusiastically to this dualfaceted approach.
Computer-aided Design, 2007
This paper applies singularity theory of mappings of surfaces to 3-space and the generic transiti... more This paper applies singularity theory of mappings of surfaces to 3-space and the generic transitions occurring in their deformations to develop algorithms for contin- uously and robustly tracking the intersection curves of two deforming parametric spline surfaces, when the deformation is represented as a family of generalized offset surfaces. The set of intersection curves of 2 deforming surfaces over all
Visualization and Data Analysis 2012, 2012
ABSTRACT SQiRL is a novel visualization system for querying and visualizing large multivariate da... more ABSTRACT SQiRL is a novel visualization system for querying and visualizing large multivariate data sets. Although initially designed for novice users, recent extensions to SQiRL facilitate more advanced analysis without sacrificing the simplicity that makes this visualization appealing to beginners. The default view provides a simple-to-learn interface for query evaluation. Intermediate users are provided a straightforward method for comparing the results of two queries. More advanced users can make use of a "radial crosstab," a new interactive visualization technique that melds the expressive power of traditional crosstabulation with a drag-and-drop canvas.
Sketch-N-Make is a prototype system that enables individ- uals to create dimensioned designs quic... more Sketch-N-Make is a prototype system that enables individ- uals to create dimensioned designs quickly for a restricted, but broadly useful, domain of machined metal and plastic prismatic parts. Process plans, xturing, tool selection, feeds and speeds, and toolpaths are automatically generated from the designs al- lowing parts to be manufactured on a machining center with the aid only of a
Volume 5: 35th Design Automation Conference, Parts A and B, 2009
Engineering designs are often determined by functional considerations, yet modeled with purely ge... more Engineering designs are often determined by functional considerations, yet modeled with purely geometric parameters. Because of this, a difficult part of a design engineer's job is tracking how changes to the geometric model might alter the functional performance of the design. This paper proposes a design interface that uses temporary functional views of geometric models to augment design engineers, helping them explore design space while continuously apprising them of the implications that modifications have on a design. The basic approach of the proposed interface is to use fast, interactive analysis tools in combination with feedback mechanisms to create temporary, functional design handles on top of the underlying geometric parametric structure. This design exploration tool is implemented in a research CAD system and demonstrated on illustrative examples.
Proceedings 2000 ICRA. Millennium Conference. IEEE International Conference on Robotics and Automation. Symposia Proceedings (Cat. No.00CH37065), 2000
We present an approach for automatically generating complete process plans, including xturing and... more We present an approach for automatically generating complete process plans, including xturing and CNC code, from high level shape feature part descriptions. The demonstration system is targeted at a broadly useful class of machined prismatic parts which includes sculpted exterior pro les and features requiring four and ve axis indexing for manufacture. The approach introduces a set of process plan templates which are schemas for a family of process plans embodying a variety of xturing strategies. The knowledge built into the process plan templates can adapt existing part hole features to be used for xturing, can modify the workpiece to enable xturing, and can create custom xturing components for stages of the process plan. The process plan template system automatically transforms a given part design into a complete process plan. The user can provide optional guidance for this transformation and also can edit the resulting process plan to further extend the usefulness of this approach through customization. Domain knowledge in the process plan then automatically generates CNC code for a target machining center. This research is implemented as an experimental subsystem within our Alpha 1 modeling and manufacturing testbed environment, and has been used to design and manufacture working components for outside client applications.
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Papers by Richard Riesenfeld