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GIS in Forestry: GIS in forestry: A bottom to top approach for high accuracy and large-scale integration of geo-spatial data
Virtual Mosaics
The way out is to employ effective drawing management. A powerful drawing management technology has been provided in the AutoCAD Data Extension (ADETm) which has the capability to access, query and display simultaneously multiple maps. Maps may also be nested.Thus, the forest map (originally digitized from paper maps on 4 1 Mile) along with all object data becomes available for the entire state to be queried, viewed, analyzed and saved as a single file in a drawing session. It is interesting to note that digitization/vectonization may be carried out for all the maps and data saved in a number of individual files, each representing the smallest management unit. At higher levels of nesting, maps can be viewed by simply attaching connected files in a drawing session. To effectively use this scheme of drawing management, maps are to be planned in advance to draw a group of related geographic entities and objects in a single file.
However, as the mapped area increases, the map co-ordinate system needs to be changed. The drawings at Level I to 3 can be based on individual polyconic projections as followed by Survey of India. However, in state level maps, the co-ordinate system may be changed to UTM or any other acceptable datum. The drawing management technology of ADETM allows automatic switeliing over and co-ordinate transformation from one system to another in attached drawings. Thus, seamless virtual mosaics of maps is achieved from bottom to top in digital maps.
The discussion in the preceding paragraphs of the section mainly concentrated on integration of vectors. But digital maps are more than a collection of vectors in different colours, they also contains object data and attributes. Not only each type of object data should preferably be placed on a uniquely defined layer with its own colour, line, thickness and pattern type, but also map should contain attribute and data attached to map objects either internally as a part of the drawing or externally through a DBMS. It is essential from the point of view of ease in working, to evolve standard codes to define layers, data tables and object data fields. Else a great chaos would result by nesting a large number of files. Such standards of data input need to be evolved by all concerned in the field of GIS. Standardization of object and data codes for digital maps requires development of a detailed system of nomenclature which should be comprehensive (to save memory and storage space) and at the same time be applicable to all geographical regions.
Map indexing schemes have little relevance in digital maps. Maps from different regions may be attached in a drawing session of ADETM , and they would appear as a single map. Using this multiple file access technology, GIS users can incorporate geo-spatial data of other regions in their drawing. For example, a GIS user in Bangladesh studying effect of deforestation on the floods caused by the Brahmaputra and the Ganges rivers, may incorporate geo-spatial maps of the North-East India, Tibet, Nepal and North-West India into his drawing session. However, such a state of affairs would require international understanding and regional co-operation.
Beyond the Political Boundaries
Regional co-operation is required especially in the mountain eco-systems where a delicate balance exists between man and nature. As because disturbance in one region may adversely affect the eco-systems elsewhere, mountain regions need to be viewed from a broader perspective. Forestry management, wildlife management, bio-diversity conservation and many such issues are inter-related in a mountain system. There is already a welcome move in the direction of transboundary wildlife and bio-diversity conservation in the Indo-Bhutan region. In the changing scenario, GIS technology can play a meaningful role in conservancy and sustainable use of natural resources, only if there is free exchange of geo-spatial database among members of the region, Institutions such as ICIN40D should take lead in development of accurate database, and their exchange, especially in the forestry, wildlife and ecology in the Hindu Kush Himalayan region.
References
- M. K. Yadava, IFS , Working Plans - The Main-stay of GIS in Forestry, MapIndia 98, 7-9 October, 1998, New Delhi,
- CI Liu, Richard (Dick) Brantigan Using Differential OPS for Forest Traverse Surveys, Can. I For. Res., 25:1795-1805 (1995)
- Kurt Novak , Mobile Mapping TechnologyfOTGIS Data Collection, Photogrammetry Engg. & Remote Sensing, Vol. 61, No. 5, May 1995, pp.493-501.
- K.R. Srinivasan, GIS/GPS Technology: The Road Ahead, GIS@,development, May-June, 1998, p.7
- Ajay Rastogi, Transboundary Co-operation for Bio-diversity Conservation and Management, ICIMOD Newsletter., No. 31, Autumn, 1998, p 10.
- AutoCAD Map Reference Manual
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