8256633
Art-based rendering of fur, grass, and trees
Artists and illustrators can evoke the complexity of fur or vegetation with relatively few well-placed strokes. We present an algorithm that uses strokes to render 3D computer graphics scenes in a stylized manner suggesting the complexity of the scene without representing it explicitly. The basic algorithm is customizable to produce a range of effects including fur, grass and trees, as we demonstrate in this paper and accompanying video. The algorithm is implemented within a broader framework that supports procedural stroke-based textures on polyhedral models. It renders moderately complex scenes at multiple frames per second on current graphics workstations, and provides some interframe coherence. CR
795737
Navigating documents with the virtual scroll ring
We present a technique for scrolling through documents that is simple to implement and requires no special hardware. This is accomplished by simulating a hardware scroll ring--a device that maps circular finger motion into vertical scrolling. The technique performs at least as well as a mouse wheel for medium and long distances, and is preferred by users. It can be particularly useful in portable devices where screen-space and space for peripherals is at a premium.
6983775
Modeling surfaces of arbitrary topology using manifolds
Manifolds describe complicated objects that are locally $\Re\sp{n}$ by defining a set of overlapping maps from the object to $\Re\sp{n}$. In this thesis we present a general technique for inverting that process: we define a complicated object from a set of overlapping subsets of $\Re\sp{n}$. We first present a constructive definition that describes how to perform such a construction in general. We then apply this construction to the particular problem of defining surfaces of arbitrary topology. The surface is built in two steps: we build a manifold with the correct topology then embed the manifold into $\Re\sp3$ using traditional spline techniques. The surface inherits many of the properties of B-splines: local control, a compact representation, and guaranteed continuity of arbitrary degree. The surface is specified using a polyhedral control mesh instead of a rectangular one; the resulting surface approximates the polyhedral mesh much as a B-spline approximates its rectangular control mesh. Like a B-spline, the surface is a single, continuous object.
6477925
Constructive solid geometry for polyhedral objects
Constructive Solid Geometry (CSG) is a powerful way of describing solid objects for computer graphics and modeling. The surfaces of any primitive object (such as a cube, sphere or cylinder) can be approximated by polygons. Being abile to find the union, intersection or difference of these objects allows more interesting and complicated polygonal objects to be created. The algorithm presented here performs these set operations on objects constructed from convex polygons. These objects must bound a finite volume, but need not be convex. An object that results from one of these operations also contains only convex polygons, and bounds a finite volume; thus, it can be used in later combinations, allowing the generation of quite complicated objects. Our algorithm is robust and is presented in enough detail to be implemented.
14187938
Smooth meshes for sketch-based freeform modeling
This paper describes a framework for introducing visually smooth surfaces into sketch-based freeform modeling systems. An existing sketch-based freeform modeling system generates rough polygonal meshes with uneven triangulations after each operation. Our approach generates a dense, visually smooth polygonal mesh by beautifying and refining the original rough mesh. A beautification process generates near-equilateral triangles with a near-uniform distribution of vertices to mask the noise and bad sampling of the uneven mesh. The vertices are distributed on a smoothed surface that approximately interpolates the original mesh. Refinement generates a smooth, dense mesh by subdividing the beautified mesh and moving the vertices to the interpolative surface. The smooth interpolative surface is computed via implicit quadratic surfaces that best fit the mesh locally in a least-squares sense.
2239491
Voice as sound: using non-verbal voice input for interactive control
We describe the use of non-verbal features in voice for direct control of interactive applications. Traditional speech recognition interfaces are based on an indirect, conversational model. First the user gives a direction and then the system performs certain operation. Our goal is to achieve more direct, immediate interaction like using a button or joystick by using lower-level features of voice such as pitch and volume. We are developing several prototype interaction techniques based on this idea, such as "control by continuous voice", "rate-based parameter control by pitch," and "discrete parameter control by tonguing." We have implemented several prototype systems, and they suggest that voice-as-sound techniques can enhance traditional voice recognition approach.
218895568
How to give a good research talk
Giving a good research talk is not easy. We try to identify some things which we have found helpful, in the hope that they may be useful to you.
8892107
Generalising monads to arrows
Abstract Monads have become very popular for structuring functional programs since Wadler introduced their use in 1990. In particular, libraries of combinators are often based on a monadic type. Such libraries share (in part) a common interface, from which numerous benefits flow, such as the possibility to write generic code which works together with any library. But, several interesting and useful libraries are fundamentally incompatible with the monadic interface. In this paper I propose a generalisation of monads, which I call arrows, with significantly wider applicability. The paper shows how many of the techniques of monadic programming generalise to the new setting, and gives examples to show that the greater generality is useful. In particular, three non-monadic libraries for efficient parsing, building graphical user interfaces, and programming active web pages fit naturally into the new framework.
16084483
Why Functional Programming Matters
As software becomes more and more complex, it is more and more important to structure it well. Well-structured software is easy to write and to debug, and provides a collection of modules that can be reused to reduce future programming costs. In this paper we show that two features of functional languages in particular, higher-order functions and lazy evaluation, can contribute significantly to modularity. As examples, we manipulate lists and trees, program several numerical algorithms, and implement the alpha-beta heuristic (an algorithm from Artificial Intelligence used in game-playing programs). We conclude that since modularity is the key to successful programming, functional programming oers important advantages for software development.
27941486
Distributed probabilistic diagnosis of MCMs on large area substrates
This paper addresses the issue of testing MCMs on large-area substrates. The cost of testing each MCM may be as high as 40% of the total manufacturing cost. It is critical that the test process be parallelized in order that multiple MCMs may be tested for the cost of testing one MCM. With this objective in mind, we propose a distributed probabilistic diagnosis algorithm for MCMs on large-area substrates. Our algorithm performs better than the existing diagnosis algorithms and can correctly identify almost all MCMs even when the yield is very low (35%). Further it provides upto an order of magnitude reduction in test application time as opposed to serial MCM probe test.
7653698
Reversing Abstract Interpretations
Program analyses are often presented as one of two brands: forwards or backwards. In this paper we explore the significance of the direction of analysis, and show how arbitrary abstract interpretations may be reversed.