Preparation of thematic maps based on interpretation of aerial photographs is an important activity of FSI. Aerial photographs procured from Survey of India are interpreted using stereoscopes. After intensive ground verification corrections are incorporated in the interpreted aerial photographs. These photographs are sent to the SOI for transference of the interpreted details on base maps on 1:50,000 scale and for preparation of thematic maps. Thematic maps depict forest types, major species composition, crown density of forest cover and other land uses. They depict as many as 48 forest types and 14 other categories of land uses. Thematic map are one of the best forest type map available in FSI. These maps are used by various State Forest Departments for updating stock maps, working plan preparations, management of forest resources and land use planning. These are also indented by Railways, Engineering, Educational, Mining and other establishments for their general planning and programme execution.
The total geographic area of the country is covered by 5,200 SOI map sheets on 1:50,000 scale. Of these about 3,400 sheets bear forest cover. Each year about 5,200 aerial photographs corresponding to 260 SOI sheets on 1:50,000 scale were interpreted for generation of thematic maps. About 75% of the forested area of the country has been covered by thematic mapping. The activity of Thematic Mapping work has been scaled down to 50 sheets per year since________. The list of thematic maps which have been prepared and interpreted till this date is given in following table.
The aerial photographs covering about of 75% forested area of the country are available in FSI. The period of photographs differs from place to place. The period of aerial photographs ranges from 1953 to 1995.
Toposheet 1:250,000 scale >> Toposheet of 1:250,000 scale are available with us almost for the entire country except few sheets that have not been supplied by SOI.
Toposheet of 1:50,000 scale >> Toposheets of 1:50,000 scale pertaining to more than 90% geographic area of the country are available with us.
Toposheets of 1:250,000 scale >> Toposheets of 1:250,000 scale pertaining to some parts of the country are available with us.
LIST OF THEMATIC MAPS AVAILABLE IN FSI