We present an algorithm for real-time level of detail reduction and display of high-complexity polygonal surface data. The algorithm uses a compact and e cient regular grid representation, and employs a variable screen-space threshold to bound the maximum error of the projected image. The appropriate level of detail is computed and generated dynamically in real-time, allowing for smooth changes of resolution across areas of the surface. The algorithm has been implemented for approximating and rendering digital terrain models and other height elds, and consistently performs at interactive frame rates with high image quality. T ypically, the number of rendered polygons per frame can be reduced by t w o orders of magnitude while maintaining image quality such that less than 5 of the resulting pixels di er from a full resolution image.

The complete structure of the red crystalline 2:1 adduct from thiobarbituric acid and malondialdehyde has been unambiguously determined by FTIR and high-field 1 H and 13C NMR studies.

No abstract

Malondialdehyde reacts readily with amino acids to form adducts containing vinylogous amidine linkages. Crosslinking reactions between nucleic acid bases and amino acids induced by malondialdehyde also have been investigated. The physical data obtained for the adducts provide structural information on the possible mode of crosslinking of proteins and nucleic acids induced by this lipid metabolite.

Advances in computer graphics hardware and algorithms, visualization, and interactive techniques for analysis offer the components for a highly integrated, efficient real-time 3D Geographic Information System. We have developed "Virtual GIS," a system with truly immersive capability for navigating and understanding complex and dynamic terrain-based databases. The system provides the means for visualizing terrain models consisting of elevation and imagery data, along with GIS raster layers, protruding features, buildings, vehicles, and other objects. We have implemented window-based and virtual reality versions and in both cases provide a direct manipulation, visual interface for accessing the GIS data. Unique terrain data structures and algorithms allow rendering of large, high resolution datasets at interactive rates.