| || Move Table: An Intelligent Software Tool for Optimal Path Finding and Halt Schedule Generation
Author : Agrawal, Anupam;Joshi, Anugrah;Radhakrishna, M.
Source : Defence Science Journal ; Vol:57(5) ; 2007 ; pp 721-732
Subject : 681.3 Computer Science
Keywords : Genetic-fuzzy approach;Move Table software;Halt schedule;Path finding;Digital elevation maps;Classification maps;Digital terrain
Abstract : This study aims to help army officials in taking decisions before war to decide the optimal path for army troops moving between two points in a real world digital terrain, considering factors like traveled distance, terrain type, terrain slope, and road network. There can optionally be one or more enemies (obstacles) located on the terrain which should be avoided. A tile-based A* search strategy with diagonal distance and tie-breaker heuristics is proposed for finding the optimal path between source and destination nodes across a real-world 3-D terrain. A performance comparison (time analysis, search space analysis, and accuracy) has been made between the multiresolution A* search and the proposed tile-based A* search for large-scale digital terrain maps. Different heuristics, which are used by the algorithms to guide these to the goal node, are presented and compared to overcome some of the computational constraints associated with path finding on large digital terrains. Finally, a halt schedule is generated using the optimal path, weather condition, moving time, priority and type of a column, so that the senior military planners can strategically decide in advance the time and locations where the troops have to halt or overtake other troops depending on their priority and also the time of reaching the destination.
| || Real-time Photorealistic Visualisation of Large-scale Multiresolution Terrain Models
Author : Agrawal, Anupam ;Joshi, R. C. ;Radhakrishna, M.
Source : Defence Science Journal ; Vol:57(1) ; 2007 ; pp 149-162
Subject : 550.3 Geophysics
Keywords : Level-of-detail management;Multiresolution modelling;Real-time rendering;Photorealistic visualisation;Terrain-rendering algorithm;Digital terrain models
Abstract : Height field terrain rendering is an important aspect of GIS, outdoor virtual reality applications such as flight simulation, 3-D games, etc. A polygonal model of very large terrain data requires a large number of triangles. So, even most high-performance graphics workstations have great difficulty to display even moderately sized height fields at interactive frame rates. To bring photorealism in visualisation, it is required to drape corresponding high-resolution satellite or aerial phototexture over 3-D digital terrain and also to place multiple collections of point-location- based static objects such as buildings, trees, etc and to overlay polyline vector objects such as roads on top of the terrain surface. It further complicates the requirement of interactive frame rates while navigation over the terrain. This paper describes a novel approach for objects and terrain visualisation by combination of two algorithms, one for terrain data and the other for objects. The terrain rendering is accomplished by an efficient dynamic multiresolution view-dependent level-of-detail mesh simplification algorithm. It is augmented with out-of-core visualisation of large-height geometry and phototexture terrain data populated with 3-D/2-D static objects as well as vector overlays without extensive memory load. The proposed methodology provides interactive frame rates on a general-purpose desktop PC with OpenGL- enabled graphics hardware. The software TREND has been successfully tested on different real-world height maps and satellite phototextures of sizes up to 16K*16K coupled with thousands of static objects and polyline vector overlays.