Potential of Geo sketches and drawings to enrich map base
Focus of GIS technology is on visualisation of information. In this context, the importance of information which is stored in the form of sketches, drawings or maps has drawn special attention. It is noted that this was probably easiest way in past to express or record information. With such traditional practices, India today, has rich heritage of information in the form of Geo sketches and drawings. This practice seems to be most prevalent for various survey activities, be it on the subject of human or natural resources. Information is recorded on the sketches of the area with important landmarks, monuments, roads etc.
The major survey organizations in the country such as Census survey, National Sample Survey or other similar organizations, have wealth of such information stored in the form of geo sketches or drawing. Millions of records to day exist which are being used in most traditional way and serve limited purpose. Bringing such information on GIS may unleash power and potential of this information beyond the imagination. This may not only tremendously enrich the map base of the country but may impact the complete survey work to keep pace with the modern development. Objective of this discussion is to highlight importance of the information which is in the form of sketches or drawings, how they differ in their representation and scope of bringing such information on GIS.
Geo Sketches are very primary form of representation where individual may express understanding of an area with different features as of his interest such as roads, name of localities, important land marks etc. These representations may not follow any scale or orientation. For a larger area, these may not be correct to represent shape or size. However, such sketches may be very helpful for the individuals to carry out their task efficiently.
Drawings on other hand consider as more evolved form of representation. They try to follow the convention of scale for representation of features. The word ” drawing” is popularly used for display of say Master plan, City layout or a construction site. Preparation of drawings shall need proper exercise on survey of area and depict all the necessary features which are required for the purpose. These may represent accurate measurements, size or shape of the area along with placement of notional objects as required.
Map is the most versatile form of representation. The scope of representation in map may not only restrict in small area but may cover the entire earth. The subject, therefore, has been extensively deliberated on how the features on earth from curved surface to be represented on plain paper. Geodesy, Geodetics Engineering or Cartography are branches of earth science that deal with the measurement and representation of the Earth or any planet. Representation of map needs to follow the concepts of scale, projection and datum. For fruitful use of maps in GIS, they must relate to certain referencing system. Hence conversion of sketches or drawings to map need to follow the concepts of “geo referencing ” . Accuracy of representation of the features with particular projection and scale is a critical debate. This is probably a reason, that in spite of most versatile maps being represented through various domestic or global map services, there has been a conservative approach on using them for undertaking area measurements for public use.
Many proof of concepts have been established and suggest that the sketches and drawings available in various organizations in the country may be converted to maps using GIS and remote sensing techniques. Conversion of such data, however, would require great deal of planning and coordination to contribute to national asset.