Head-mounted displays for virtual environments facilitate an immersive experience that seems more real than an experience provided by a desk-top monitor [18]; however, the cost of head-mounted displays can prohibit their use. An empirical study was conducted investigating differences in spatial knowledge learned for a virtual environment presented in three viewing conditions: head-mounted display, large projection screen, and desk-top monitor. Participants in each condition were asked to reproduce their cognitive map of a virtual environment, which had been developed during individual exploration of the environment along a predetermined course. Error scores were calculated, indicating the degree to which each participant's map differed from the actual layout of the virtual environment. No statistically significant difference was found between the head-mounted display and large projection screen conditions. An implication of this result is that a large projection screen may be an effective, inexpensive substitute for a head-mounted display.

We present a method for dynamically generating an efficient texture bitmap and its associated UV-mapping in an interactive texture painting system for 3D models. Typical 3D texture painting programs require the user to explicitly define the underlying UV-mapping from 3D geometry to 2D bitmap prior to painting. This mapping is unchanged by the painting process. However, a predefined UV-mapping can cause distortion at arbitrary locations and waste bitmap memory in unpainted areas.To solve these problems, we propose an adaptive unwrapping mechanism where the system dynamically creates a tailored UV-mapping for newly painted polygons during the interactive painting process. This eliminates the distortion of brush strokes, and the resulting texture bitmap is more compact because the system allocates texture space only for the painted polygons. In addition, this dynamic texture allocation allows the user to paint smoothly at any zoom level. This technique can be efficiently implemented using standard 3D rendering engines, and the painted models can be stored as standard textured polygonal models. We implemented a prototype system, called Chameleon, and our users' experiences suggest that our technique is very useful for simple painting by casual users.

In this paper, we describe a pedagogy for an undergraduate programming course using Alice 3 and Java. We applied the educational theory of mediated transfer to develop a new version of the Alice system and accompanying instructional materials.The pedagogy was implemented and tested over two years. Student test scores in experimental, treatment course sections showed dramatic improvement over scores in comparable nontreatment sections.

Enabling middle school children to learn from code shared on the internet may provide computer science learning opportunities to those who would not otherwise have them. We augmented a programming environment designed for middle school children to automatically generate tutorials from code snippets in order to help users learn new programming skills. In our new system, users select code snippets from a program shared on the web and then complete an automatically generated tutorial in order to re-create that snippet within their own program. To evaluate the potential learning gains from our generated tutorials, we conducted a between-subjects study in which we evaluated the performance of children introduced to new programming constructs through automatically generated tutorials. Participants who used the automatically generated tutorials performed 64% better on a near transfer task compared to participants without generated tutorials.

We present lessons learned from developing Alice, a 3D graphics programming environment designed for undergraduates with no 3D graphics or programming experience. Alice is a Windows 95/NT tool for describing the time-based and interactive behavior of 3D objects, not a CAD tool for creating object geometry. Our observations and conclusions come from formal and informal observations of hundreds of users. Primary results include the use of LOGOstyle egocentric coordinate systems, the use of arbitrary objects as lightweight coordinate systems, the launching of implicit threads of execution, extensive function overloading for a small set of commands, the careful choice of command names, and the ubiquitous use of animation and undo.