Spatial Information Technology — NCERT Solutions

GIS has several advantages over manual methods. It allows separate data storage and presentation, lets users interrogate spatial features and retrieve attribute information, can draw maps by querying attribute data, supports spatial operations like overlay and buffering to generate new information, and can associate different attribute data through shared location codes.

The important components of GIS are hardware, software, data, people and procedures. Hardware includes input, output, storage and processing units; software handles data entry, editing, analysis and display; data are the spatial and attribute records; people use and manage the system; and procedures are the methods for handling data through the system.

Spatial data can be built in GIS core in three ways: acquiring digital data sets from a data supplier, digitising existing analogue data, and carrying out one’s own surveys of geographic entities. The chapter also mentions scanning and digitisation as common manual input methods.

Spatial Information Technology refers to the use of technological inputs for collecting, storing, retrieving, displaying, manipulating, managing and analysing spatial information. It is an amalgamation of Remote Sensing, GPS, GIS, Digital Cartography and Database Management Systems.

The raster data format represents a geographic feature as a pattern of cells or pixels arranged in a grid. It is suitable for satellite images, aerial photographs and scanned maps, and is useful where cost is low and individual feature analysis is not needed. The vector data format stores features as points, lines and polygons using coordinate pairs. It is suitable for precise mapping, network analysis and storing descriptive information. For example, a satellite image is raster, while a road, river or administrative boundary map is vector.

The sequence of GIS-related activities is: (1) spatial data input, (2) entering attribute data, (3) data verification and editing, (4) spatial and attribute data linkages, and (5) spatial analysis. First, spatial data are acquired by digitising, scanning or importing digital data. Then attribute data are entered from records, surveys or spreadsheets. Next, the data are checked and corrected for omissions, wrong scale and distortion. After that, spatial and attribute files are linked using common identifiers or matching methods. Finally, spatial analysis such as overlay and buffer analysis is carried out to generate useful information and support decision-making.