NCERT Class 12 Practical Geography Chapter 4: Use of Computer in Data Processing and Mapping

Get unlimited access to the best preparation resource for CBSE/Class-12 : get questions, notes, tests, video lectures and more- for all subjects of CBSE/Class-12.

NCERT Class 12 Practical Geography Chapter 4: Use of Computer in Data Processing and Mapping

What Computers Do?

What Computers Do?
  • computer is an electronic device. It consists of various sub-systems, like memory, micro-processor, input system and output system.
  • computer is a fast and a versatile machine that can perform simple arithmetic operations, such as, addition, subtraction, multiplication and division, and can also solve complex mathematical, formulae. It also performs simple logical operations, distinguishing zero from non-zero and plus from minus and discharge the results. In short, a computer is a data processor that can perform substantial computation, including numerous arithmetic or logical operations, without intervention by a human operator during the run.


The Hardware Components

The hardware components of a computer include:

  • A Central Processing Unit (CPU) and Storage System - facilitates the execution of program instructions for processing data and controlling peripheral equipment โ€“ hardware (1to 4 GB, RAM 32MB, Disk storage, OS - MS-DOS, Windows, and UNIX)
  • A Graphic Display Sub-system - userีšs prime visual communication medium, display Colours and Look-up Tables (LUT)
  • Input Devices โ€“ keyboards (cursor on screen) ; scanners, digitizers
  • Output Devices - printers, such as ink-jet, laser and colour laser printers; and the plotters


Types of Software

Computer software is a written program that is stored in memory:

  • Data Entry and Editing Modules - data entry system interface, database creation, error removal, scale and projection manipulations, their organisation and maintenance. Data - MS Excel/Spread sheet, Lotus 1 โ€“ 2 โ€“ 3, and d โ€“ base; mapping โ€“ Arc View/Arc GIS, Geomedia
  • Coordinate Transformation and Manipulation Modules - used to create layers of spatial data, coordinate transformation, editing and linking the spatial data sets with the related non-spatial attributes of data

Data Display and Output Modules:

  • Zooming/Windowing to display of selected areas and scale change operation
  • Colour assignment/change operation
  • Three dimensional and perspective display
  • Selective display of various themes
  • Polygon shading, line styling and point markers display
  • Output device interface commands for interfacing with plotter devices/printers
  • Graphic User Interface (GUI) based menu organisation for an easy interface

Software for Use

Software for Use
  • MS Excel or Spreadsheet program. The spreadsheet enables us to feed data
  • An Excel worksheet contains 16,384 rows, numbered 1 through 1,6384 and 256 columns, represented by default through letters A through Z, AA through AZ, BA through BZ, and continuing to IA through IZ. By default, an Excel workbook consists of three worksheets. If you require, you can insert more, up to 256 worksheets
  • A cell can contain a numerical value, a formula (which after calculation provides numerical value) or text. Texts are generally used for labelling numbers entered in the cells. A value entry can either be a number (entered directly) or result of a formula.

Data Entry


Operators and formulas = SUM (A1: A5)

Ctrl + N = new file

Ctrl + O = existing file

Ctrl + C = copy

Ctrl + X = cut

Ctrl + V = paste

Ctrl + Z = undo last action

Ctrl + Y = redo last action

= A8/ (A9 + A4) - It will first add the values entered in cells A9 and A4, and then will divide the value of A8 by the sum

Data Entry: Storage

The use of worksheet functions to compute these statistics of mean, mode, median.

Data Entry: Storage

Computer Assisted Mapping

Computer Assisted Mapping

integration with attribute or non- spatial data. It further involves the verification and structuring of the stored data.

Spatial Data

  • Point, Line, Area
  • Point data represent positional characteristics of some of the geographical features, such as schools, hospitals, wells, tube-wells, towns and villages
  • Linear features, like roads, railway lines, canals, rivers, power and communication lines
  • Polygons are made of a number of inter-connected lines, bounding a certain area, and are used to show area features such as administrative units (countries, districts, states, blocks) ; land use types (cultivated area, forest lands, degraded/waste lands, pastures, etc.) and features, like ponds, lakes.

Non-Spatial Data

  • name of the school, subject stream it offers, number of students in each class, schedule of admissions, teaching and examinations, available facilities
  • The geographical data are available in analogue (map and aerial photographs) or digital form (scanned images)
  • mapping softwareีšs, such as ArcGIS, ArcView, Geomedia, GRAM, Idrisi, Geomatical.

Opensource โ€“ QGIS

  • choropleth mapping using a mapping software
  • onscreen digitization of scanned maps, corrections of errors, transformation of scale and projection, data integration, map design, presentation and analysis
  • A digitized map consists of three files. The extensions of these files are shp, shx and dbf. The dbf file is dbase file that contains attribute data and is linked to shx and shp files. The shx and shp files, on the other hand, contain spatial (map) information. The dbf file can be edited in MS Excel
  • A choropleth map is a type of thematic map in which areas are shaded or patterned in proportion to a statistical variable that represents an aggregate summary of a geographic characteristic within each area, such as population density or per-capita income.

Developed by: