An efficient voxel representation scheme coupled with algorithms for voxelisation, display and thickness analysis of complex free form shapes is presented. The binary voxel model is stored as a stack of layers represented as bit-arrays. Polygonal solid models are converted into voxel format with a maximum resolution of 1000 (one billion voxels) in less than 2 minutes. Near real-time visualization of the voxel model is achieved by direct point rendering using a look-up table based on a finite set of neighbour voxel configurations. Thickness analysis is performed in terms of cross-sectional visualisation, progressive skin removal and radiography with minimum, maximum and total thickness along an orthographic direction. Testing of the algorithms for intricate shapes like Ganesha idol, pelvis bone and automobile cylinder gave satisfactory results. The voxel framework can be coupled to traditional CAD/CAM systems, providing additional capabilities to product engineers.

Software packages NUPARM and NUCGEN, are described, which can be used to understand sequence directed structural variations in nucleic acids, by analysis and generation of non-uniform structures. A set of local inter basepair parameters (viz. tilt, roll, twist, shift, slide and rise) have been defined, which use geometry and coordinates of two successive basepairs only and can be used to generate polymeric structures with varying geometries for each of the 16 possible dinucleotide steps. Intra basepair parameters, propeller, buckle, opening and the C6...C8 distance can also be varied, if required, while the sugar phosphate backbone atoms are fixed in some standard conformation in each of the nucleotides. NUPARM can be used to analyse both DNA and RNA structures, with single as well as double stranded helices. The NUCGEN software generates double helical models with the backbone fixed in B-form DNA, but with appropriate modifications in the input data, it can also generate A-form DNA and RNA duplex structures.