Geoprocessing II

esf Laboratory for Applied GIS 2 Just what is Geoprocessing? Geoprocessing is used by everyone that uses ArcGIS. Whether you're a new user or an old pro, geoprocessing will become an essential part of your day-to-day work with ArcGIS. (esri) So we have to emphasize it!

esf Laboratory for Applied GIS 3 Two flavors of Geoprocessing Process modeling –What we have been talking about –Is a model of a physical process –Can be static or dynamic – iteration Simulation –Explicitly model a process in time

esf Laboratory for Applied GIS 4 Simulation Model a phenomenon in time –Example: Forest fire growth Create realizations of a phenomenon as it moves through space and time with changing variables (fuel load, weather) Can be Deterministic or Stochastic

esf Laboratory for Applied GIS 5 Simulations Deterministic –Model with well understood rules Stochastic –Have a component of randomness Don’t fully understand the rules Error in input data (very common) Error in model parameters Interactions between layers (propagation of error)

esf Laboratory for Applied GIS 6 More? This gets pretty complex and the online help system has some very good discussions on the subject. Got to –bhelp.esri.com/arcgisdesktop/9.2/index. cfm?id=923&pid=921&topicname=General _concepts_of_modeling_through_simula tionsbhelp.esri.com/arcgisdesktop/9.2/index. cfm?id=923&pid=921&topicname=General _concepts_of_modeling_through_simula tions

esf Laboratory for Applied GIS 7 Its Purpose Almost all uses of GIS involve repetition The automation of geospatial tasks –Saves time –Provides documentation –Share methods These methods are called Workflows

esf Laboratory for Applied GIS 8 Workflows A Workflow is a collection of Steps and data that define the paths that can be taken to complete a task.... So when presented with a problem with a set of criteria that must be met You generate a workflow

esf Laboratory for Applied GIS 9 A Problem Task is to find tax parcels that could possibly be used for a nature center –Are at least 20 acres in size –Have both forest and Agricultural lands –Are within 6 miles of each of the town’s schools –Contain a stream or river (or be on a river bank) –Preferable the parcel should be owned by the town or the state

esf Laboratory for Applied GIS 10 And the derived workflow is… 1.What tools would be used for each of the criteria? 2.In what order would these sub- tasks be undertaken? 3.Graphically…

esf Laboratory for Applied GIS 11 Schematically Data Process Data Process Or by text list

esf Laboratory for Applied GIS 12 A Problem Task is to find tax parcels that could possibly be used for a nature center –Are at least 20 acres in size –Have both forest and Agricultural lands –Are within 6 miles of each of the town’s schools –Contain a stream or river (or be on a river bank) –Preferable the parcel should be owned by the town or the state