Introduction To GIS
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This document provides an overview of Geographic Information Systems (GIS) and Remote Sensing. It will cover the theoretical background, tools and techniques used in GIS and remote sensing, and geospatial analysis using ArcGIS. Key topics include what a GIS is, its components and functions like data assembly, storage, analysis, manipulation and output. Representation of spatial elements as raster and vector data, and how attributes are associated with spatial features is also described. The document contrasts raster and vector data, and discusses desktop GIS software like ArcGIS.
Introduction To GIS
- 1. Geographical InformationGeographical Information System & Remote SensingSystem & Remote Sensing (GEO 212)(GEO 212)
- 2. What we will do?What we will do? Theoretical background on GIS and RS Tools and techniques used in GIS/RS Geospatial analysis using ArcGIS
- 3. Introduction to GISIntroduction to GIS
- 4. A GIS is a system (hardware + database engine) that is designed to efficiently, assemble, store, update, analyze, manipulate, and display geographicallygeographically referenced informationreferenced information (data identified by their locations). ++ Information System Geographic Position What is GIS?What is GIS? GIS = Geographic Information System
- 5. GIS links graphical features (entities) to tabular data (attributes) What is GIS?What is GIS?
- 6. Data can be: 1. Positioned by its known spatial coordinates 2. Input and organized (generally in layers) 3. Stored and retrieved 4. Analyzed (usually via a Relational DBMS) 5. Modified and displayed Key Functions of a GISKey Functions of a GIS
- 7. GIS System and ComponentsGIS System and Components
- 8. Decision GISGIS ProcessProcessOutput GIS analysis Import or build datasets Define GIS criteria Define problem Geographic Information SystemsGeographic Information Systems
- 9. Representing Spatial ElementsRepresenting Spatial Elements Raster Vector Real World
- 10. Raster: Stores images as rows and columns of numbers with a Digital Value/Number (DN) for each cell. Units are usually represented as square grid cells that are uniform in size. Data is classified as “continuous” (such as in an image), or “thematic” (where each cell denotes a feature type. Numerous data formats (TIFF, GIF, ERDAS.img Representing Spatial ElementsRepresenting Spatial Elements
- 11. Vector: Allows user to specify specific spatial locations and assumes that geographic space is continuous, not broken up into discrete grid squares We store features as sets of X,Y coordinate pairs. Representing Spatial ElementsRepresenting Spatial Elements
- 12. Entity RepresentationsEntity Representations Points - simplest element Lines (arcs) - set of connected points Polygons - set of connected lines We typically represent objects in space as three distinct spatial elements: We use these three spatial elements to represent real world features
- 13. AttributesAttributes • In the raster data model, the cell value (Digital Number) is the attribute. Examples: brightness, rainfall value, landcover code, SST, etc. • For vector data, attribute records are linked to point, line & polygon features. Vector data can store multiple attributes per feature. Vector features are linked to attributes by a unique feature number.
- 14. Raster vs. VectorRaster vs. Vector Raster Advantages 1. The most common data format Easy to perform mathematical and overlay operations 2. Satellite information is easily incorporated 3. Better represents “continuous”- type data Vector Advantages 1. Accurate positional information that is best for storing discrete thematic features (e.g., roads, shorelines, sea-bed features. 2. Compact data storage requirements 3. Can associate unlimited numbers of attributes with specific features
- 15. • Data Assembly • Data Storage • Spatial Data Analysis and Manipulation • Spatial Data Output GIS FunctionsGIS Functions
- 16. Data AssemblyData Assembly Maps Satellite Information Data Transfer Direct Entry GPS Manual Digitizing Scanning Database Data Transfer Keyboard Image Processing Data Extraction GIS FunctionsGIS Functions
- 17. GIS StorageGIS Storage GIS FunctionsGIS Functions Spatial data (ARC functions) Attribute data (INFO or TABLES functions) 1 (Universe polygon) 2 3 4 5 3 COV# ZONE ZIP 1 0 2 C-19 22060 3 A-4 22061 4 C-22 22060 5 A-5 22057
- 18. Spatial AnalysisSpatial Analysis Overlay function creates new “layers” to solve spatial problems
- 19. • Tables • Maps • Interactive Displays • 3-D Perspective View Spatial Data OutputSpatial Data Output GIS FunctionsGIS Functions
- 20. Is GIS about software only?Is GIS about software only? • A Geographic Information System is not only about computers, software and electronic data. • A GIS is an organised collection of : • Hardware • Software • Network • Data • Procedures • And people!
- 21. Desktop GISDesktop GIS • A GIS, or GIS software, allows you to interactively work with spatial data. • A desktop GIS is a mapping software that needs to be installed onto and runs on a personal computer. • In this course, we will use ArcGIS which is developed by ESRI.
- 22. ESRI ArcGIS SystemESRI ArcGIS System Clients FilesFiles (Personal(Personal Geodatabase,Geodatabase, Shapefiles, Coverages,Shapefiles, Coverages, Grids, tins, etc)Grids, tins, etc) ArcSDE Services Database storage/access DatabasesDatabases Multi-userMulti-user GeodatabasesGeodatabases (in Oracle, SQL(in Oracle, SQL Server,Server, IBM DBII, etc)IBM DBII, etc) ArcInfo ArcEditor ArcMap ArcIMS Services Map display & query ArcExplor er Browser ArcPad ArcEngine/ ArcObjects Application Development & Customization x: ArcGIS Workstation Consistent interface Increasing capability ArcCatalog ArcToolbox ArcCatalog ArcToolbox ArcCatalog ArcToolbox Source: ESRIHandheld/Wireless ArcServer Services Full GIS analysis