Sketching communicates ideas rapidly through approximate visual images with low overhead (pencil and paper), no need for precision or specialized knowledge, and ease of low-level correction and revision. In contrast, most 3D computer modeling systems are good at generating arbitrary views of precise 3D models and support high-level editing and revision. TheSKETCH application described in this paper attempts to combine the advantages of each in order to create an environment for rapidly conceptualizing and editing approximate 3D scenes. To achieve this, SKETCH uses simple non-photorealistic rendering and a purely gestural interface based on simplified line drawings of primitives that allows all operations to be specified within the 3D world.

Direct volume-rendering has proven to be an effective and flexible visualization method for 3D scalar fields. Transfer functions are fundamental

Most direct volume renderings produced today employ one-dimensional transfer functions, which assign color and opacity to the volume based solely on the single scalar quantity which comprises the dataset. Though they have not received widespread attention, multi-dimensional transfer functions are a very effective way to extract specific material boundaries and convey subtle surface properties. However, identifying good transfer functions is difficult enough in one dimension, let alone two or three dimensions. This paper demonstrates an important class of three-dimensional transfer functions for scalar data (based on data value, gradient magnitude, and a second directional derivative), and describes a set of direct manipulation widgets which make specifying such transfer functions intuitive and convenient. We also describe how to use modern graphics hardware to interactively render with multi-dimensional transfer functions. The transfer functions, widgets, and hardware combine to form a powerful system for interactive volume exploration.

Almost as long as there have been user interfaces, there have been special software systems and tools to help design and implement the user interface software. Many of these tools have demonstrated significant productivity gains for programmers, and have become important commercial products. Others have proven less successful at supporting the kinds of user interfaces people want to build. This article discusses the different kinds of user interface software tools, and investigates why some approaches have worked and others have not. Many examples of commercial and research systems are included. Finally, current research directions and open issues in the field are discussed.

developing distributed, interactive 3D graphics applications across a range of heterogeneous workstations. Repo-3D is designed to make it easy for programmers to rapidly build prototypes using a familiar multi-threaded, object-oriented programming paradigm. All data sharing of both graphical and non-graphical data is done via general-purpose remote and replicated objects, presenting the illusion of a single distributed shared memory. Graphical objects are directly distributed, circumventing the “duplicate database” problem and allowing programmers to focus on the application details. Repo-3D is embedded in Repo, an interpreted, lexically-scoped, distributed programming language, allowing entire applications to be rapidly prototyped. We discuss Repo-3D’s design, and introduce the notion of local variations to the graphical objects, which allow local changes to be applied to shared graphical structures. Local variations are needed to support transient local changes, such as highlighting, and responsive local editing operations. Finally, we discuss how our approach could be applied using other programming languages, such as Java.

It is often difficult in computer graphics applications to understand spatial relationships between objects in a 3D scene or effect changes to those objects without specialized visualization and manipulation techniques. We present a set of three-dimensional tools (widgets) called "shadows" that not only provide valuable perceptual cues about the spatial relationships between objects, but also provide a direct manipulation interface to constrained transformation techniques. These shadow widgets provide two advancesover previous techniques. First, they provide high correlation between their own geometric feedback and their effects on the objects they control. Second, unlike some other 3D widgets, they do not obscure the objects they control. Keywords Direct Manipulation, 3D Widgets, Interactive Systems 1 Introduction A wide variety of techniques for visualizing and manipulating objects have beenimplemented in interactive 3D graphics applications for modeling, animation, simulation an...

We explore a range of techniques that use two hands to control two independent cursors to perform operations in 3D desktop applications. Based on research results in 2D applications, we believe that two-handed input provides the potential for creating more efficient and more fluid interfaces, especially for tasks that are context-sensitive or that have many degrees of freedom. These tasks appear frequently in 3D applications and are commonly broken down into a series of sequential operations, each controlling fewer degrees of freedom -- even though this may dramatically change the character of the task. However, two-handed interaction, in theory, makes it possible to perform the same tasks using half the number of sequential steps since two previously sequential operations can be performed simultaneously. In addition, many forms of two-handed interaction may be simpler to use and to understand since they correspond to common interactions in the physical world. It is significant when ta...

Distributed Open Inventor is an extension to the popular Open Inventor toolkit for interactive 3D graphics. The toolkit is extended with the concept of a distributed shared scene graph, similar to distributed shared memory. From the application programmer's perspective, multiple workstations share a common scene graph. The proposed system introduces a convenient mechanism for writing distributed graphical applications based on a popular tool in an almost transparent manner. Local variations in the scene graph allow for a wide range of possible applications, and local low latency interaction mechanisms called input streams together with a sophisticated networking architecture enable high performance while saving the programmer from network peculiarities. Keywords Distributed graphics, concurrent programming, scene graph, distributed virtual environment, computer supported cooperative work, virtual reality 1.

We present a paradigm and toolkit for rapid prototyping of interactive, animated 3D graphics programs. The paradigm has its roots in declarative programming, emphasizing immutable values, first class functions, and relations, applying these concepts to a broad range of types, including points, vectors, planes, colors, transforms, geometry, and sound. The narrow role of modifiable state in this paradigm allows applications to be run in a collaborative setting (multi-user and multi-computer) without modification. CR Categories and Subject Descriptors: I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism; I.3.6 [Computer Graphics]: Methodology and Techniques; D.1.1 [Pro- gramming Techniques] Applicative (Functional) Programming; D.2.m [Software Engineering] Miscellaneous Rapid Prototyping; G.1.7 [Mathematics of Computing] Ordinary Differential Equations. Additional Keywords and Phrases: Local Propagation Constraints 1 Introduction TBAG is a paradigm and toolkit for ra...

: We introduce a local collaborative environment for gaming. In our setup multiple users can interact with the virtual game and the real surroundings at the same time. They are able to communicate with other players during the game. We describe an augmented reality setup for multiple users with see-trough head-mounted displays, allowing dedicated stereoscopic views and individualized interaction for each user. We use face-snapping for fast and precise direct object manipulation. With face snapping and the subdivision of the gaming space into spatial regions, the semantics of actions can be derived out of geometric actions of the user. Further, we introduce a layering concept allowing individual views onto the common data structure. The layer concept allows to make privacy management very easy by simply manipulating the common data structure. Moreover, assigning layers to spatial regions carefully, a special privacy management is often not necessary. Moving objects from one region into ...