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Item Constructive Cubes: CSG Evaluation For Display Using Discrete 3-D Scalar Data Sets(Eurographics Association, 1991) Breen, David E.The algorithm presented in this paper converts a CSG model into a representation for interactive display on an engineering workstation. Called Constructive Cubes, the algorithm extends the standard CSG-point classification algorithm and then employs a popular isosurface generation algorithm, Marching Cubes, to generate a list of polygons that approximates the surface of a CSG model. The polygons may then be interactively displayed, shaded and inspected on a workstation. The algorithm has many advantages over other CSG algorithms. It is straightforward to implement, requiring no complex surface intersection calculations. The algorithm provides an inherent flexibility that allows a user to balance the time/quality trade-off. It is designed to take advantage of current and future advances in both visualization and engineering workstation design.Item Interactive Occlusion and Automatic Object Placement for Augmented Reality(Blackwell Science Ltd and the Eurographics Association, 1996) Breen, David E.; Whitaker, Ross T.; Rose, Eric; Tuceryan, MihranWe present several techniques for producing two visual and modeling effects in augmented reality. The first effect involves interactively calculating the occlusions between real and virtual objects. The second effect utilizes a collision detection algorithm to automatically move dynamic virtual objects until they come in contact with static real objects in augmented reality. All of the techniques utilize calibrated data derived from images of a real-world environment.Item Object Calibration for Augmented Reality(Blackwell Science Ltd and the Eurographics Association, 1995) Whitaker, Ross T.; Crampton, Chris; Breen, David E.; Tuceryan, Mihran; Rose, EricAugmented reality involves the use of models and their associated renderings to supplement information in a real scene. In order for this information to be relevant or meaningful, the models must be positioned and displayed in such a way that they align with their corresponding real objects. For practical reasons this alignment cannot be known a priori, and cannot be hard-wired into a system. Instead a simple, reliable alignment or calibration process is performed so that computer models can be accurately registered with their real-life counterparts. We describe the design and implementation of such a process and we show how it can be used to create convincing interactions between real and virtual objects.Item Distributed Augmented Reality for Collaborative Design Applications(Blackwell Science Ltd and the Eurographics Association, 1995) Ahlers, Klaus H.; Kramer, Andre; Breen, David E.; Chevalier, Pierre-Yves; Crampton, Chris; Rose, Eric; Tuceryan, Mihran; Whitaker, Ross T.; Greer, DouglasThis paper presents a system for constructing collaborative design applications based on distributed augmented reality. Augmented reality interfaces are a natural method for presenting computer-based design by merging graphics with a view of the real world. Distribution enables users at remote sites to collaborate on design tasks. The users interactively control their local view, try out design options, and communicate design proposals. They share virtual graphical objects that substitute for real objects which are not yet physically created or are not yet placed into the real design environment.We describe the underlying augmented reality system and in particular how it has been extended in order to support multi-user collaboration. The construction of distributed augmented reality applications is made easier by a separation of interface, interaction and distribution issues. An interior design application is used as an example to demonstrate the advantages of our approach.