6699728
Art-based rendering with continuous levels of detail
In previous work [6], we presented an algorithm for rendering virtual scenes using art-based styles. We demonstrated the ability to render fur, grass, and trees in a stylized manner that evoked the complexity of these textures without representing all their components explicitly. We achieved this with stroke-based procedural textures that generated detail elements, or graftals, just as needed. Our implementation had several drawbacks. First, each new graftal texture required a procedural implementation that included writing code. Also, graftals were regenerated in each frame in a way that led to excessive introduction and elimination of graftals even for small changes in camera parameters. Lastly, our system provided no way to continuously vary the properties of graftals, including color, size, or stroke width. Such an ability could be used to achieve better frame-to-frame coherence, or more generally to animate graftals. In this paper, we present a new framework for graftal textures that addresses these issues. Our new framework allows all major decisions about graftal look and behavior to be specified in a text file that can be edited by a designer. We have achieved greater frameto-frame coherence by using graftals that remain in fixed positions on the model surface. The look and behavior of graftals as they appear or disappear can now be animated to create smooth transitions. Finally, we introduce the concept of tufts which manage the multiresolution behavior of graftals according to the specifications of the scene designer.
7017581
Multi-finger cursor techniques
The mouse cursor acts as a digital proxy for a finger on graphical displays. Our hands, however, have ten fingers and many degrees of freedom that we use to interact with the world. We posit that by creating graphical cursors that reflect more of the hand's physical properties, we can allow for richer and more fluid interaction. We demonstrate this idea with three new cursors that are controlled by the user's fingers using a multi-point touchpad. The first two techniques allow for simultaneous control of several properties of graphical objects, while the third technique makes several enhancements to object selection.
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.
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.
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.
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.
8283585
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.
17667421
Assessing undergraduate experience of continuous integration and test-driven development
A number of agile practices are included in software engineering curricula, including test-driven development. Continuous integration often is not included, despite it becoming increasingly common in industry to code, test, and integrate at the same time. This paper describes a study whereby software engineering undergraduates were given a short intensive experience of test-driven development with continuous integration using an environment that imitated a typical industrial circumstance. Assessment was made of students' agile experience rather than of project deliverables, using a novel set of process measures that examined students' participation and performance in agile testing. Results showed good participation by student pairs, and clear understanding of agile processes and configuration management. Future work will investigate automation of the assessment of continuous integration and configuration management server data.
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.
14958709
Making choices lazily
We present a natural semantics that models the untyped, normal order A-calculus plus McCarthy’s amb in the context of call-by-need parameter passing. This results in a singular semantics for amb. Previous work on singular choice has concentrated on erratic choice, a less interesting nondeterministic choice operator, and only in relation to callby-value parameter passing, or call-by-name restricted to deterministic terms. The natural semantics contains rules for both convergent and divergent behaviour, allowing it to distinguish programs that differ only in their divergent behaviour. As a result, it is more discriminating than current domain-theoretic models. This, and the fact that it models singular amb, makes the natural semantics suitable for reasoning about lazy, functional languages containing McCarthy’s amb.
8161135
Binding-Time Analysis for Polymorphic Types
Offline partial evaluators specialise programs with annotations which distinguish specialisation-time (or static) computations from run-time ones. These annotations are generated by a binding-time analyser, via type inference in a suitable type-system. Henglein and Mossin developed a type system which allows polymorphism in binding-times, so that the same code can be specialised with different computations being static at different uses. We extend their work to permit polymorphism in types as well. This is particularly important for separately compiled libraries.Following Henglein and Mossin, binding-times are passed as parameters during specialisation, but types are not. Instead, we pass coercion functions when necessary, which makes specialisation less "interpretive" than it would otherwise be. We keep track of the coercions needed by assigning qualified types to polymorphic functions.We also consider hand-annotations to provide limited user control over the binding-time analysis, which our prototype implementation showed to be necessary.