(GIS) Geographical Information System Essay Example | Topics and Well Written Essays - 2250 words

(GIS) Geographical Information System - Essay Example The hardware component of GIS is the central processing unit (CPU) or computer. It also includes a digitizer scanner whose function is to change data for example those found in maps into digital form then send the converted data to the CPU. There are also a tape device whose function is to store programs or data on magnetic tap, and a display device which is used to display data that has been processed. People as a component of GIS include end users and specialists whose function is to design the GIS for the end users. Methods refer to those procedures or techniques used data collection or processing. The functional elements of GIS are data manipulation, data input and output, data retrieval and display, data analysis and modelling and data management. Data input refers to incorporating data into the GIS whereas data output refers to removing data or information from the GIS. Data analysis and modelling involves obtaining an understanding of relationships in the data collected and de veloping a model of the spatial phenomena. Data retrieval entails taking out data from a stored format for use whereas data display is the showing off of the derived or primary data (Delaney and Niel 2006). In GIS, spatial data represent features that are location-specific or geographic in nature. They include cell location like column and raw, and coordinates like longitudes and latitudes. On the other hand, attribute data give a description of feature in a specific location and they can be in numbers or text strings. Unlike spatial data, attribute data can be measured in ratio, ordinal, interval and nominal ratios. According to Delaney and Niel (2006), topology creates an awareness of the surrounding for the GIS by developing a spatial data relationship. It links spatial and attribute data to give information on what surrounds a feature. When representing continuous and discrete geographic features, vector data structure uses points, polygons and lines whereas raster data structur e make tessellation on the representation surface through a repeated use of a square cell or a pixel. However, raster data structures are better at representing a continuous surface. Vector data structure support typology better and are more accurate in representing geographic features compared to raster data structure. Generally, raster data structure requires has a lower processing power requirement compared to vector data structure. On-screen digitising, converting, importing and geo-locating/geo-rectification are the four common methods of incorporating digital data into a GIS. On-screen digitising involves locating features from digital sources for example satellite or scanned images using a computer mouse. Attribute data is entered through computer keyboard. Geo-locating is used to input non-geographic/non-georeferenced data into GIS because it converts spatial data into geographic data. Converting is done if GIS data is in a format that cannot be used by certain software. Imp orting involves obtaining data from other sources like geo-coded textual data, satellite images or digital aerial photographs into the GIS. There exist differences in cost, effort, time, and editing requirements between on-screen digitising, converting, importing and geo-locating/geo-rectification, scanning and vectorisation, table digitizing and keyboard entry as data input methods. Both importing and converting are fast, cheaper, need less efforts and have less editing requireme