Shader-based OpenGL is a powerful and exciting tool for individuals with data visualization needs, interests in gaming, a need to create and manipulate synthetic environments, and a variety of other high-performance tasks. It is well-known that shader-based OpenGL is difficult to learn for programmers with no prior graphics API experience -- some have even claimed it's impossible to teach to individuals without such prior exposure. In this paper, we report on our experiences developing an educational approach that we believe has contributed to the base of evidence that it is not only possible, but also desirable to do so. Our overriding goal has been to learn and exploit the extent to which mastering a complex graphics API like modern shader-based OpenGL can be enhanced by using a software design framework into which relevant concepts can be placed, thus facilitating more rapid assimilation and mastery of the concepts. We have been using this technique in our Introduction to Computer Graphics course in which we have two primary goals: teach shader-based OpenGL to students who have no prior experience using a graphics API, and present a framework to students that will scale up to medium and large scale applications, both in terms of code size as well as data size. We do not in any way suggest that our architecture is the 'best' for all advanced graphics applications, or even for teaching. Instead we simply claim that use of such a framework helps students master complex OpenGL concepts and develop nontrivial interactive 3D applications. Once students fully understand the basics, they should find it easy to migrate to other perhaps quite different architectures.

Metaview is an interactive tool that helps to teach concepts related to nested 3D coordinate systems, especially in the context of defining and establishing views of 3D scenes in common graphics APIs like OpenGL and Direct3D. We describe the context in which nested coordinate systems arise in the study of graphics programming, then we relate the common conceptual difficulties students typically experience when studying and trying to put this material into practice. We then describe the role that metaview plays in helping to overcome these problems. Space allows us only to describe its core uses in these areas; several of its additional features are briefly listed at the end. Metaview is packaged with a set of built-in 3D models used to demonstrate major concepts. In addition, external and/or student-programmed models are easily imported into the tool. Metaview can be run anywhere, anytime using Java Web Start. The latest released version of the tool can be executed from http://people.eecs.ku.edu/~miller/JOGL/metaview.jnlp. We are currently working on a port to OpenGL ES targeted for portable smart devices such as tablet computers.

evaluation; guidelines; usability testing; cognitive walkthrough A user interface (UI) for a software product was evaluated prior to its release by four groups, each applying a different technique: heuristic evaluation, software guidelines, cognitive walkthroughs, and usability testing. Heuristic evaluation by several ill specialists found the most serious problems with the least amount of effort, although they also reported a large number of low-priority problems. The relative advantages of all the techniques are discussed, and suggestions for improvements in the techniques are offered.

Macaulay's concise but explicit expression for nmltivariate resultants has many potential applications in computer-aided geometric design.Here we describe its use in solid modeling for finding the intersections of three implicit quadric surfaces.By B6zout's theorem, three quadric surfaces have either at most eight or intlnitely many intersections.Our method finds the intersections, when there are finitely many, by generating a polynomial of degree at most eight whose roots are the intersection coordinates along an appropriate axis.Only addition, subtraction, and multiplication are required to find the polynomial.But when there are pmsibilities of extraneous roots, division and greatest common divisor computations are necessary to identify and remove them.

In contrast to the common view of spreadsheets as “single-user” programs, we have found that spreadsheets offer surprisingly strong support for cooperative development of a wide variety of applications. Ethnographic interviews with spreadsheet users showed that nearly all of the spreadsheets used in the work environments studied were the result of collaborative work by people with different levels of programming and domain expertise. Cooperation among spreadsheet users was spontaneous and casual; users activated existing informal social networks to initiate collaboration.

“Wizard of Oz” techniques were used to observe the interaction between users of a statistical package and a human playing the role of an simulated intelligent advisory system. The results emphasized the complexities of the advisory process. More than half of the clients' requests sought help on planning actions toward achieving task goals. Further, protocols collected from the advisor while advice was given revealed the importance of constructing models of the user's current and past interaction with the application, and of addressing the high-level goals that underlie clients' explicit questions. The relevance of these findings to the development of intelligent advisory systems is discussed.

Quadric surfaces occur frequently in the design of discrete piece parts in mechanical CAD/CAM. Solid modeling systems based on quadric surfaces must be able to represent intersection curves parametrically and in a fashion that allows the underlying surfaces to be partitioned. An algebraic approach originally developed by Levin meets these needs but is numerically sensitive and based on solutions to fourth-degree polynomial equations. In this paper we develop geometric approaches that are robust and efficient, and do not require solutions to polynomials of degree higher than 2.

This paper describes the NLMenu System, a menu-based natural language understanding system. Rather than requiring the user to type his input to the system, input to NLMenu is made by selecting items from a set of dynamically changing menus. Active menus and items are determined by a predictive left-corner parser that accesses a semantic grammar and lexicon. The advantage of this approach is that all inputs to the NLMenu System can be understood thus giving a 0% failure rate. A companion system that can automatically generate interfaces to relational databases is also discussed.