Functions of GIS 30/04/2010 Major Functions of GIS 1. Data Capture • Data used in GIS often come from many different sources, are of many types, and are stored in different ways. • GIS provides tools and a method for the integration of different data into a format to be compared and analysed. • Data sources are mainly manual digitization/scanning of aerial photographs, paper maps, and existing digital datasets. Remote-sensing satellite imagery and GPS are promising data input sources for GIS. Major Functions of GIS 2.Database Management and Update • After data are collected and integrated, the GIS must provide facilities which can contain and maintain data. • Effective data management has many definitions but should include all of the following aspects: – data security – data integrity – data storage – retrieval, and – data maintenance abilities. Major Functions of GIS 3. Geographic Analysis • Data integration and conversion are only a part of the input phase of GIS. What is required next is the ability to interpret and to analyse the collected information quantitatively and qualitatively. For example, a satellite image can assist an agricultural scientist to project crop yield per hectare for a particular region. For the same region, the scientist also has the rainfall data for the past six months collected through weather station observations. The scientist also has a map of the soils for the region which shows fertility and suitability for agriculture. These point data can be interpolated and what you get is a thematic map showing iso-heights or contour lines of rainfall. Major Functions of GIS 4.Presenting Results • One of the most exciting aspects of GIS technology is the variety of different ways in which the information can be presented once it has been processed by GIS. • Traditional methods of tabulating and graphing data can be supplemented by maps and three dimensional images. • Visual communication is one of the most fascinating aspects of GIS technology and is available in a diverse range of output options. FOUR Ms of GIS Measurements Mapping Monitoring Modeling Time-1 Time-2 Time-3 Updating Adapted from J.Stars and J.Estates Spatial Analyses Measurements GPS Data Recording Form Field Map Mapping Deep water table Shallow water table Monitoring July, 1999 June, 2000 Ucchali Lake, Salt Range S n ow Le op ard R iv ers P a n th e ra u n c ia G ru_ gru (C o m m on C ran e) P a k is tan B oun da ry S n ow Le op ard R iv ers P a n th e ra u n c ia A n t_v ir (D e m o is elle C ra ne ) P a k is tan B oun da ry D is trib u tio n Crane M ap Common S n ow Le op ard R iv ers P a n th e ra u n c ia G ru_ le u (S ibe rian C ran e) P a k is tan B oun da ry C om m o n C ra ne G ru s g ru s M igran t Modeling Demoiselle D is trib u tio n M aCrane p M a jo r R iv ers P a kis tan B oun da ry D em oise lle C ran e A n th ro p o id e s v irg o M igran t D is trib u tio nCrane M ap Siberian M a jo r R iv ers P a kis tan B oun da ry S ibe rian C ra ne G ru s le u c o g e ra n u s M igran t M a jo r R iv ers P a kis tan B oun da ry Indus Flyway One way of understanding GIS is to look at the problems it can solve… Questions a GIS can answer • There are five types of question that a sophisticated GIS can answer 1 Location:What is at...? – To find what exists at a particular location – A location can be described in many ways; • place name, • post code, or • geographic reference such as longitude/latitude or x and y Questions a GIS can answer 2 Condition: Where is it...? – Find location(s) where certain conditions are satisfied – e.g., non-forested section of at least 2,000 square metres in size, within 100 metres of a road, and with soils suitable for supporting buildings 3 Trends: What has changed since...? – To find the differences within an area over time – e.g., changes in land use of a block of land over the last 10 years Questions a GIS can answer 4 Patterns: What spatial pattern exists...? – E.g., landslides are mostly occurring where; • slopes are high, • soil is not stable and • vegetation is low Questions a GIS can answer 5 Modelling: What if...? – What if a toxic substance seeps into the local groundwater supply? – Use GIS to calculate how far it will spread, how quickly, the level of toxins at a given location, etc.