Introduction to GIS Learning Objectives Lecture Outline

Introduction to GISLearning Objectives• Explain a GIS its uses• List different GIS data types• Argue the need for managing GPSdata capture• Explain the link between GPS datacapture and GISLecture Outline• What Is GIS• GIS Data Types• Data Dictionary• GPS for GIS1

What is GIS?• Geographic Information System• Essentially an informationmanagement system– Integrates and stores datacollected from different sources• Set of tools for:– Capture– Storage– Analysis– OutputWhat is a GIS?• “… a powerful set of tools forcollecting, sorting, retrieving at will,transforming, analysing, anddisplaying spatial data from the realworld for a particular set ofpurposes”– Source Huxhold, An Intro to Urban GIS, 1991, quotingBorrughGIS ComponentsDATAREALITYSTORE CAPTURETRANSFORMPRESENTKNOWLEDGEIMPRESSION2

What is a GIS?• A GIS is a database managementsystem for spatially distributedfeatures and the associatedattributes– Spatial data capture– Management– Analysis– Display– Decision making– ResearchUses for a GIS• Mapping geographicalcharacteristics for analysis• Modeling alternative processesfor management plans• Managing a utility’s assets• Monitoring changes inenvironmental factorsIntegration of Data• GIS data – spatial relations anddatabases• A GIS allows integration of datacollected:– At different times– At different scales– Using various methods of capture3

Data Capture Sources• Digitizing from paper maps• Scanning• Traditional surveying techniques• Paper records & field notes• Photogrammetry• Remote sensing• GPSGIS Data Storage• There are two main types of datain a GIS database• Cartographic - observations onspatially distributed features,activities, or events, which aredefinable as:– Points– Lines (Arcs)– Areas (Polygons)GIS Data Storage• Non-Cartographic - descriptiveinformation in a database aboutthe cartographic features locatedon a map– Attributes– Attribute Values4

Point Features• Spatially distributed entities,activities or events• Points have a singlegeographic coordinatesuch as:– Tree– Traffic accident– Lamp postLine Features• Spatially distributed entities,activities or events• Lines (Arcs) are a series ofgeographic coordinates joined toform a line such as:– Road– Stream– RailwayArea Features• Spatially distributed entities,activities or events• Areas (Polygons) are a series ofgeographic coordinates joinedtogether to form a boundary suchas:– Lake– Soil types5

Attributes• Description or characteristic of afeature• Possible attributes for the featureTree– Height– Diameter– Species– Condition– AgeAttribute Values• The value given to an attribute• Possible values for the attributesof a Tree feature– Height = 15m– Diameter = 0.75m– Species = Oak– Condition = Good– Age = 8 yearsTypes of Attribute Values• There are a number of differenttypes of attribute valuesFeature Attribute Attribute ValuesCharacter Pole Pole ID ABC123Numeric Pole Height 15mMenu Pole Condition GoodAveragePoorDate Pole Date User generatedAuto generatedTime Pole Time User generatedAuto generated6

What Data is in Your GIS?• What features do you map?• What attributes do you need tocollect data on?• What attribute values can yougive the attribute?GIS Data Analysis• A GIS identifies relationshipsamong features in the database• Provide answers to queries thatare spatial (geographic)GIS Data Analysis• For example:– What is on...?– What is near...?– What is the closest...?– How far...?– How many...?– How does...?– Where is...in relation to...?– Why is...?7

Query and AnalysisData Query OutputSFBSoil Type - Area feature- Soil typesUnhealthytreesgrowingon landfillMapTrees on landfillTrees - Species- HealthReport- 3 trees growing onland fill- 2 trees are unhealthyData OrganizationTreeHealthGoodPoorSpeciesPineoakFeature nameAttributenamesAttributevaluesSoilTypeDepthFill 50Sand 125Data Input Requirements• Structured• Feature classification• Feature name• Attribute valuesFile 1 - Point Attributes1. Tree Good Pine2. Tree Poor oakFile 3 - Polygon Attributes1. Soil Fill 502. Soil Sand 125• Geographic locations– Single coordinatefor point features– Multiple coordinatesfor line and area featuresFile 2 - PointCoordinates1. X Y Z2. X Y ZFile 4 - PolygonCoordinates1. X1 Y1 Z1X2 Y2 Z2Xn Yn Zn2. X1 Y1 Z1etc.....8

ConclusionYou can now:• Explain what a GIS is and what itis used for• List different data types that canbe input to GIS• Argue the need to managefeatures and attributes collection• Explain the link between GPSdata capture and GISSelf Study• Read relevant module in StudyBook• Do self assessment quizReview Questions9