Martin Usoh

Creating animations using virtual reality ThatcherWorld: a case study

This paper describes the creation of a Western shootout animation for a BBC2 television production. This provides a case study describing the interaction between the TV production team and the animators. The animation was produced by explicitly programming transformations applied to nodes in hierarchical models of simple human characters. A subsequent project has attempted to provide character animation making use of the human body tracking and immersion afforded by virtual reality systems. In the new system a human actor can enter into a virtual environment (VE), act out a role, resulting in a file containing a script. While the script is replayed the actor can enter again into the VE, and interact with the first virtual character, and so on for subsequent replays. The paper describes a first version of this system, and provides a critical examination of the use of VR for creating animations.<<ETX>>

Using visualisation as a tool for model-based recognition

The aim of the work reported here is to build a useful toolset for 3D model-based vision on an SIMD parallel machine, the AMT DAP. Included in the toolset are facilities for model specification, manipulation and rendering using a ray-tracing approach as well as model recognition and validation using a geometrical-matching approach. In particular, an SIMD parallel version of a ray tracer and an SIMD parallel version of a bottom-up geometrical matcher are described. The ray tracer can render constructive solid geometry models and incorporates spatial subdivision of the scene. The matcher uses edge primitives recovered from scenes to match to model edges using local constraints and deals with spurious data using bin assignments. The overall toolset is illustrated by its use in closed-form testing and refinement, where the models, camera geometry and frame-to-frame motion in an image sequence generated by the ray tracer are known, but are checked and validated using geometrical matching, recognition and localisation.

SIMD algorithm for curved object recognition using Grimson and Lozano-Pérez matching

The complexity of many computer-recognition problems is such that speed of processing is an important factor that cannot be overlooked, especially when real-time applications are sought. In order to reduce the processing time of matching, our work is implemented in parallel on SIMD architecture. We describe an extension of the Holder and Buxton algorithm (1989) using the surface normal and axis of rotation of objects as ‘edge’ features to increase the object-recognition scope to objects containing developable surfaces. In addition, we implement an improved data-sorting algorithm that gives impressive speed ups compared with the earlier sorting technique. We show the method to be highly effective in the fast determination of scene interpretations with tests using artificial scenes generated efficiently by a parallel ray caster incorporating constructive solid geometry (CSG). Accuracy and robustness are further tested by application to a real-world scene.