GIS Models and ModelingIntroductionGIS ModelingThree ScenariosBinary modelsSlide 6Index ModelsRegression ModelsProcess ModelsGIS Models and GIS Models and ModelingModelingChapter 14Chapter 14IntroductionIntroductionA model is a simplified representation A model is a simplified representation of a phenomenon or systemof a phenomenon or systemGIS modeling is as the use of GIS in GIS modeling is as the use of GIS in the process of building models with the process of building models with spatial data.spatial data.spatial dataspatial datause of modelinguse of modelingdiscipline specificdiscipline specificGIS ModelingGIS ModelingGIS assists modelingGIS assists modelingIntegration of different sources then able Integration of different sources then able to link and display together.to link and display together.Vector or raster?Vector or raster?Raster: continuous, remotely sensedRaster: continuous, remotely sensedVector: well defined locations and shapes Vector: well defined locations and shapes or network.or network.Can be integration of vector and raster.Can be integration of vector and raster.Just GIS or linked to other packages?Just GIS or linked to other packages?Three ScenariosThree ScenariosLoose coupling Loose coupling transfer of files to other programstransfer of files to other programsexportexportexample statistical packagesexample statistical packagesTight couplingTight couplingcommon user interface or menu selection common user interface or menu selection to callto callEmbedded system Embedded system menus to call subsystems (ESRI products)menus to call subsystems (ESRI products)Binary modelsBinary modelsA binary model uses logical expressions A binary model uses logical expressions to select map features from a composite to select map features from a composite map or multiple grids.map or multiple grids.Map overlay to prepare for vector queryMap overlay to prepare for vector queryMultiple grid process for rasterMultiple grid process for rasterSiting common application with Siting common application with multiple criteria (example multiple criteria (example Conservation Reserve ProgramConservation Reserve Program))Binary modelsBinary modelsBinary models can be used for Binary models can be used for change detection.change detection.Sometimes binary models are used Sometimes binary models are used at the beginning stage of modeling.at the beginning stage of modeling.Index ModelsIndex ModelsAn index model used the index value An index model used the index value calculated from a composite map or calculated from a composite map or multiple grids to produced a ranked map.multiple grids to produced a ranked map.Selected variables are evaluated at two Selected variables are evaluated at two levelslevelsRelative importance, assigning a weightRelative importance, assigning a weightObserved values are evaluated and given Observed values are evaluated and given scores.scores.ArcView Model BuilderArcView Model BuilderSuitability and vulnerability analysisSuitability and vulnerability analysisRegression ModelsRegression ModelsRegression model relates a dependent Regression model relates a dependent variable to a number of independent variable to a number of independent variables in an equation.variables in an equation.Linear regression is used when the Linear regression is used when the dependent variables and independent dependent variables and independent variables are all numeric.variables are all numeric.Logistic regression is used when the Logistic regression is used when the dependent variable is a binary dependent variable is a binary phenomenon and the independent phenomenon and the independent variables are categorical or numeric.variables are categorical or numeric.Process ModelsProcess ModelsA process model integrates existing A process model integrates existing knowledge about the environmental knowledge about the environmental processes in the real world into a set of processes in the real world into a set of relationships and equations for relationships and equations for quantifying the process.quantifying the process.Universal Soil Loss Equation (USLE)Universal Soil Loss Equation (USLE)Agricultural Nonpoint Source (AGNPS)Agricultural Nonpoint Source (AGNPS)Soil and Water Assessment Tool (SWAT)Soil and Water Assessment Tool (SWAT)Typically raster-basedTypically raster-basedMost commercial GIS do not offer.Most commercial GIS do not