|
3D-GIS of IIRS campus using ARC-view
Final results were obtained by the thematic overlays on TIN features, as 2D themes. Digital Elevation Models were obtained as 3D themes by the overlay of extruded elevated features such as buildings, trees etc. over the TIN. Various GIS surface analysis such as calculation of area and volume of DEM, line of sight analysis, measuring and profiling height along a line were carried out and contour maps, aspect maps etc. were constructed.
 Figure 1: 3-D view of IIRS campus Results and Discussion Surface area was measured along the slope of a surface (TIN of the campus contour map), taking height into consideration. The base height above which the surface area was calculated was taken as 677 m, the lowest contour for the entire study area. Volume reported represents the space that's above the plane and under the surface. The base height above which the volume was calculated was taken as 677m, the lowest contour for the entire study area. The surface area and volume calculated for the TIN is as follows :
Volume of water body In the present study, a water conservation structure (check dam) was digitised at a suitable location on the down stream end of a gully and then added as a 3-D theme over a selected subset of the terrain TIN surface. The volume of the space between the TIN surface and the horizontal plane passing through the top of the check dam was calculated to measure the total volume of water that can be retained inside the structure. The planimetric area, surface area and volume is given below.
 Figure 2: View of the proposed water conservation structure Analyzing visibility Line of sight from a point near the GID building to a point near the IIRS gate was determined. The visible portions of the line to the target was added in green; and the non visible portion is in red. The Arc View status bar at the bottom of the application window indicated that the target location was invisible. The first obstruction point along the line of sight was shown as a blue point graphic and the xy coordinates of the obstruction was reported in the status bar. Measuring and profiling height along a line In the present study, the proposed straight road from the GID building to type E quarters over the gully gave the variation in height and terrain along the straight road. Measuring the steepest path downward from a point The steepest path downward from a point helps to find out the water flow characteristics over a terrain as water generally follows the drain along the slope. Several points located at higher elevations within the campus were selected and the steepest path downward from the points were found out using the steepest path tool in surface analysis. The following figure shows steepest paths downward from different points selected within the campus. Acknowledgements: The author acknowledges the Indian Institute of Remote Sensing, Dept. of Space, Dehradun for rendering necessary assistance and guidance in carrying out the above work using the facilities of Institute.
Page 2 of 2
| Previous | |