Atul Sahai
Pan India Consultants
India is experiencing a tremendous growth after the introduction of economic liberalisation policies in late 80’s. With the emergence of newer economic zones and day by day increasing financial potentials, the urban centre in India are growing in unprecedented rate. Take for example the mega cities of India (Delhi, Mumbai, Calcutta, Chennai, Bangalore, Ahemdabad) whuch have witnessed 3-4 times faster growth ratesthan expected. This brings with itself the inherent problems of metrosnoise & air pollution, grossly inadequate drainage and suffocating transport system with frequent system failures. To streamline the utility services for urban development and planning, the Data Based NManagement Systems (DBMS) have to be developed in a GIS environment generoulsy using Remote Sensing products. With the advent of high resolution multirole sensors, this area is surging ahead with a wealth of terrain information coming at microlevel and new products will emerge from the synthesis of electro-optical, multispectral, hyperspectral, radar and infrared imagery. Each sensor will have a unique contribution of its own and would offer composite products which are high on value addition.
The fastest growing amongst, GIS utility market segments are electric and water supply, gas, telephone (and now cellular networking too), transport network (also alternate routing), Landuse development/planning etc. The other GIS Applications includes Facility Management (FM) i.e. support, plan, update and display of civic facilities (sewer, water, electricity/telephone cables, hospitals, roads, parks, schools, recreation facilities, etc.), Land parcel boundaries, inventory of public/ Govt. owned property; transportationplanning/vehicle routing etc. The applciations are mind boggling and the list enhances each day but it also poses a query regarding the choice right blend of data structure and package. As Granger, rightly points towards this problem, as a cultural difference between end users, one the natural resource investigator, who uses/integrate Remote Sensing with Raster GIS systems withsynoptic coverage of specific themes. While hey typically produce vector maps as an outcome of their work, most of the spatial modelling, analysis and interpretation is conducted in a raster environment. The other group of end users are land administrators, surveyors, engineers and cartographers with a focus on large scale, and AM/FM based packages (mainly vector based). However, there are areas where these are overlaid/overlapped like defence, emergency management and development planning.
In micro-level AM/FM for urban planning there is a urgent need of the fusion of the two to give the best utility maps. In this context Digital Elevation Models (DEM’s) fused with high resolution satellite Images to produce Digital Terrain Models (DTM’s), provide a real time 3D terrain models which can be extensively used for any AM/FM application. The relationship of Digital Terrain Modelling to other closely related fields (as referred above) of digital mapping, AM/FM; and geographic and land Information Systems (GIS/LIS) is very important, since all are concerned with spatial data about theterrain surface and the objects occuring on it. However, at present level, GIS, LIS, and AM/FM are less integrated with DTM, since presently the emphasis for DTM’s is more on surface form of terrain as represented by a set of elevation values at known locations (X,Y&Z). Thus mostly DTM’s are restricted terrain information and often does not contain cultural information (roads, buildings, cadastres etc.) as displayed in a topographical map. Also many of the current GIS, LIS and AM/FM systems are designed only to deal with 2D data and not the 3D data as generated and handled by a terain modelling system.
However, in coming years the situation will see a world of changes and DTM’s with value addition will play a vital role in AM/FM
