Base Map Preparation Process -1

Preparation of master plan starts with base map preparation before which relevant data of all the necessary information, which is to be presented via base, map is collected. For base map preparation, National Urban Information System (NUIS) Scheme has prepared maps on 1:10,000 scale and made available on NRSC/ISRO Geoportal Bhuvan for Urban Local Bodies for 152 towns. Bhuvan NUIS GIS database comprises 

1)Base layers

Road, Rail, Canal, Transportation nodes, Drainage, Surface water Bodies. 

2)Thematic layers

Urban Land use / Cover, Geomorphology, Lithology, Geological structures, Physiography 

3)Administrative Layers

State, District, Village, City/Town boundaries and Ward Boundaries. Attribute data has spatial layers as, administrative boundaries, forest boundary, settlement and village locations / names and city / town boundaries and non‐spatial data. Other sources of licensed/authentic versions of interpreted satellite imageries can also be used for preparation of base map. 

The Thematic GIS databases available on Bhuvan range from a scale of 1:10,000, to 1:250,000. The important Satellite data and thematic GIS data resources available for utilization for various planning and development are listed below.

Table Bhuvan Satellite data and thematic GIS data resources available

Table Base and Thematic GIS data services

Once the base and thematic layers from the satellite imagery are prepared, other city/town specific information such as, cadastral maps, revenue records, and plans of government agencies and attribute information from Industrial Development Corporations, Public Work Department, Railways, National Highway Authority could be integrated for preparation comprehensive GIS database as required for development plan/ master plan preparation. 

The satellite imageries, Resources at LISS‐4 and Cartosat PAN, can be overlaid on cadastral maps to prepare base map. These satellite images depict field bunds, cart tracks, settlements, tanks and other cultural features like roads, railway network and canals. These features facilitate identification of Ground Control Points (GCP) for tie down satellite image and cadastral map. For overlaying cadastral map with satellite image it is required that cadastral map be generated in vector mode. In this process the main tasks are acquisition of cadastral maps, scanning and digitization of cadastral maps and generation of vector data. Once the cadastral maps in vector mode are available, the geo‐referencing of these maps can be done. The geo‐referencing of digital cadastral maps and overlaying with satellite image consists of the following steps:

• Acquisition of GCP’s 
• Transformation model development and assessment 
• Geo‐referencing of cadastral maps 
• Validation of Geo‐referenced map, in isolation 
• Validation of Geo‐referenced map, with neighbourhood 
• Mosaic generation at Revenue Inspector (RI), Taluk and district level

Good planning and engineering practice dictate the preparation of large-scale maps as a basis for sound community development and redevelopment. In urban areas. and particularly ingrowing urban areas, such large scale maps are currently being compiled at an unprecedented rate by photogrammetric methods. Relatively simple changes in the specifications governing these photogrammetric mapping operations can make the resulting maps not only more effective planning and engineering tools but can, at relatively little additional cost, lay the foundation for the eventual creation of a multipurpose cadastre. 

Design of the base mapping data content and structure must be flexible enough to allow a variety of users to relate the cadastral parcels to specific types of base information. This objective can readily be achieved by creating and maintaining the base mapping data in a coordinated series of different levels or overlays. Photographic and orthophotographic base maps at a minimum contain the complete photographic image of the terrain surface covered to which other levels or overlays may be added to create the complete base map. The primary base map datum is the geodetic reference framework used to establish the location of all other features. The following reference systems are in current use throughout the United States: 

1. Geographic Coordinates (latitude and longitude) 
2. Universal Transverse Mercator (UTM) rectangular coordinates 
3. State Plane Coordinates  

Geographic coordinates provide the principal system used for computation of geodetic control point positions. The UTM rectangular coordinate system is a metric worldwide system of predominate use in federal mapping environments. State plane coordinates are most commonly used at the state and local levels, currently defined in English units but with metric units also widely available. Because of the greater familiarity with their use at the local level, State Plane Coordinates are normally used as the geodetic reference framework in current implementation projects and are recommended for local multipurpose cadastres.