Presence: Teleoperators and Virtual Environments

doi: 10.1162/105474698565488pmid: N/A

doi: 10.1162/105474698565488pmid: N/A

Semwal, Sudhanshu K.; Hightower, Ron; Stansfield, Sharon

doi: 10.1162/105474698565497pmid: N/A

In a virtual environment for small groups of interacting participants, it is important that the physical motion of each participant be replicated by synthetic human forms in real time. Sensors on a user's body are used to drive an inverse kinematics algorithm. Such iterative algorithms for solving the general inverse kinematics problem are too slow for a real-time interactive environment. In this paper we present analytic, constant time methods to solve the inverse kinematics problem and drive an avatar figure. Our sensor configuration has only eight sensors per participant, so the sensor data is augmented with information about natural body postures. The algorithm is fast, and the resulting avatar motion approximates the actions of the participant quite well. This new analytic solution resolves a problem with an earlier iterative algorithm that had a tendency to position knees and elbows of the avatar in awkward and unnatural positions.

Semwal, Sudhanshu K.; Hightower, Ron; Stansfield, Sharon

doi: 10.1162/105474698565497pmid: N/A

In a virtual environment for small groups of interacting participants, it is important that the physical motion of each participant be replicated by synthetic human forms in real time. Sensors on a user's body are used to drive an inverse kinematics algorithm. Such iterative algorithms for solving the general inverse kinematics problem are too slow for a real-time interactive environment. In this paper we present analytic, constant time methods to solve the inverse kinematics problem and drive an avatar figure. Our sensor configuration has only eight sensors per participant, so the sensor data is augmented with information about natural body postures. The algorithm is fast, and the resulting avatar motion approximates the actions of the participant quite well. This new analytic solution resolves a problem with an earlier iterative algorithm that had a tendency to position knees and elbows of the avatar in awkward and unnatural positions.

Lau, Rynson W.H.; Green, Mark; To, Danny; Wong, Janis

doi: 10.1162/105474698565505pmid: N/A

Many multiresolution methods have been proposed. Most of them emphasize accuracy and hence are slow. Some methods may be fast, but they may not preserve the geometry of the model. Although there are a few real-time multiresolution methods available, they are developed mainly for handling large terrain models. In this paper, we present a very efficient multiresolution method for continuously reducing the resolution of a triangle model by incrementally removing triangles from it. The algorithm is simple to implement, requires no complicated data structures, and has a linear triangle deletion rate. We also present a method for caching the most recent sequence of triangle removal operations into a list, called the simplification list, so that it is possible to continuously increase the resolution of the model by inserting triangles in the reverse order of the sequence. We will compare our method with Hoppe's progressive meshes. Towards the end of the paper, we discuss the performance and memory usage of our method.

Lau, Rynson W.H.; Green, Mark; To, Danny; Wong, Janis

doi: 10.1162/105474698565505pmid: N/A

Many multiresolution methods have been proposed. Most of them emphasize accuracy and hence are slow. Some methods may be fast, but they may not preserve the geometry of the model. Although there are a few real-time multiresolution methods available, they are developed mainly for handling large terrain models. In this paper, we present a very efficient multiresolution method for continuously reducing the resolution of a triangle model by incrementally removing triangles from it. The algorithm is simple to implement, requires no complicated data structures, and has a linear triangle deletion rate. We also present a method for caching the most recent sequence of triangle removal operations into a list, called the simplification list , so that it is possible to continuously increase the resolution of the model by inserting triangles in the reverse order of the sequence. We will compare our method with Hoppe's progressive meshes. Towards the end of the paper, we discuss the performance and memory usage of our method.

Kitamura, Yoshifumi; Smith, Andrew; Takemura, Haruo; Kishino, Fumio

doi: 10.1162/105474698565514pmid: N/A

We propose an accurate collision detection algorithm for use in virtual reality applications. The algorithm works for three-dimensional graphical environments where multiple objects, represented as polyhedra (boundary representation), are undergoing arbitrary motion (translation and rotation). The algorithm can be used directly for both convex and concave objects and objects can be deformed (nonrigid) during motion. The algorithm works efficiently by first reducing the number of face pairs that need to be checked accurately for interference, by first localizing possible collision regions using bounding box and spatial subdivision techniques. Face pairs that remain after this pruning stage are then accurately checked for interference. The algorithm is efficient, simple to implement, and does not require any memory-intensive auxiliary data structures to be precomputed and updated. The performance of the proposed algorithm is compared directly against other existing algorithms, e.g., the separating plane algorithm, octree update method, and distance-based method. Results are given to show the efficiency of the proposed method in a general environment.

Kitamura, Yoshifumi; Smith, Andrew; Takemura, Haruo; Kishino, Fumio

doi: 10.1162/105474698565514pmid: N/A

We propose an accurate collision detection algorithm for use in virtual reality applications. The algorithm works for three-dimensional graphical environments where multiple objects, represented as polyhedra (boundary representation), are undergoing arbitrary motion (translation and rotation). The algorithm can be used directly for both convex and concave objects and objects can be deformed (nonrigid) during motion. The algorithm works efficiently by first reducing the number of face pairs that need to be checked accurately for interference, by first localizing possible collision regions using bounding box and spatial subdivision techniques. Face pairs that remain after this pruning stage are then accurately checked for interference. The algorithm is efficient, simple to implement, and does not require any memory-intensive auxiliary data structures to be precomputed and updated. The performance of the proposed algorithm is compared directly against other existing algorithms, e.g., the separating plane algorithm, octree update method, and distance-based method. Results are given to show the efficiency of the proposed method in a general environment.

Cohen, Michael; Koizumi, Nobuo

doi: 10.1162/105474698565523pmid: N/A

Audio windowing is a front-end, or user interface, to an audio system with a real-time spatial sound back end. Complementing directionalization by a digital signal processor (DSP), gain adjustment is used to control the volume of the various mixels (sound mixing elements). Virtual gain can be synthesized from components derived from collective iconic size, mutual distance, orientation and directivity, and selectively enabled according to room-wise partitioning of sources across sinks. This paper describes a derivation of virtual gain, and outlines the deployment of these expressions in an audio windowing system.

Cohen, Michael; Koizumi, Nobuo

doi: 10.1162/105474698565523pmid: N/A

Audio windowing is a front-end, or user interface, to an audio system with a real-time spatial sound back end. Complementing directionalization by a digital signal processor (DSP), gain adjustment is used to control the volume of the various mixels ([sound] mixing elements). Virtual gain can be synthesized from components derived from collective iconic size, mutual distance, orientation and directivity, and selectively enabled according to room-wise partitioning of sources across sinks. This paper describes a derivation of virtual gain, and outlines the deployment of these expressions in an audio windowing system.