Lecture-8a_Bb_3SlidesPerPage

Lecture-8a_Bb_3SlidesPerPage - Introduction Introduction to...

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Unformatted text preview: Introduction Introduction to Geoprocessing Geoprocessing With ArcGIS 9 What Is Geoprocessing? Definition Definition A GIS operation used to manipulate GIS GIS data. The application of a clearly defined operation that creates new spatial data from existing or derived data. In In other words… It It allows us to ask questions of our GIS database that cannot be answered by the RAW data. Common Common Geoprocessing Tasks Data Data Conversion Shapefile Shapefile to Geodatabase Feature Class Overlay Overlay Operations Union and/or Intersection Data Data Extraction Defining Defining a subset through Clipping or Filter Proximity Proximity Analysis Buffering Buffering Site Site Selection Employ Employ Various ArcGIS Extensions ArcGIS Geoprocessing ArcGIS ArcGIS Implements Geoprocessing Through The Use Of Toolboxes Accessed from: Accessed from: ArcToolbox, ArcCatalog Tree, or Geodatabase ArcToolbox Tools Tools are typically accessed through ArcToolbox A dockable window dockable with toolboxes Since ArcGIS 9, the User may dock in ArcCatalog, ArcMap, ArcScene and ArcGlobe ArcToolbox ArcToolbox ArcToolbox ArcToolbox Tabs Favorites Favorites list of toolboxes available to use for current session use for current session user can add/remove toolbox Index: Index: Search tools alphabetically Search: Search: Search tools by keyword Supported Data Types ArcGIS ArcGIS 8.x, ArcToolbox ArcToolbox worked primarily with Coverages Shapefiles/Feature Shapefiles/Feature Classes employed the Geoprocessing Wizard; very limited! ArcGIS ArcGIS 9 It It is claimed ArcToolbox can work with all data types used in ArcGIS, even layers! ArcGIS Geoprocessing Toolboxes Toolboxes contain Toolsets and Tools Tools Tools Requires interaction from user prior to functioning System System Tools Pre-Loaded, written by ESRI Read-Only Custom Custom Tools Produced by the User System System Tools Core Core Toolsets Analysis Analysis Geoprocessing for Feature Classes Cartography Cartography Conversion Conversion Data Data management Geocoding Geocoding Linear Linear Referencing Spatial Spatial Statistics Coverage Coverage Geoprocessing for Coverages ArcInfo workstation installation only Number of tools •ArcView: 102 •ArcEditor: 104 •ArcInfo: 251 •Spatial Analyst: 158 •3D Analyst: 45 •Geostatistical Analyst: 1 ArcGIS Geoprocessing Tools Tools May Be Run: Via Via their dialog box, At the command At the command line, line, Within Within a script or a model. Running Running tools via dialog box Find Find the tool from toolbox. Double click to activate Dialog Dialog boxes guide you through the process of running a tool Lets Lets you specify the source data and other parameters Great Great for beginners Help Help readily available Messages Messages appear in progress dialogs Running Running tools at the Command Line The The command line is similar to the ArcInfo Workstation command line (but for ArcInfo/ArcEditor/ArcView) You You type a tool name, set appropriate parameter values, then press Enter to execute the tool. Quicker if you Quicker if you know know what you’re doing Less Less Intuitive Usage Usage of the tool is shown as you type Build and Run a Model For For geoprocessing involving multiple tools Create Create a new model by linking the tools together in a graphical environment Documentation Documentation of of model process Easily Easily change parameters and rere-execute model Models A model contains one or model more processes A process contains a tool process element and its parameter values values. Tool Tool Project Project data data exists before the model is run Derived Derived data output data created by a tool Input Input value and derived value non-geographic values as input or output Building Building the Model Drag Drag and drop data and tools from ArcCatalog or ArcMap Link Link data and tools using connector Set Set input/output data and tool parameters (right click/open) Building the Model Expose Expose input/output data or tool parameters to dialog forms Input/Output Input/Output Data right click> model parameter Tool Tool right click> make variable> from parameter click> make variable> from parameter right click> create parameter Running the Model Three Three states of a model Not Not ready to run: parameters not defined; white background hit Ready Ready to run colored Already Already run colored and shadowed A model is run in model either Model builder or Toolbox. Create Create and Run a Script To To automate geoprocessing tasks with scripts written in COM-compliant scripting language to COMexecute ArcGIS geoprocessing tools Python, VBScript, Jscript, Perl Python, VBScript, Jscript, Perl # Import system modules import sys, string, os, win32com.client gp = win32com.client.Dispatch ("esriGeoprocessing.GpDispatch.1") ... gp.workspace = “c:\\GISI” Fcs = gp.ListFeatureClasses(“*“, “all“) Clipfc = “c:\\GISI\\FL_boundary.shp” Outworkspace = “c:\\GISI\\results” fc = fcs.next() while fc: outname = outworkspace + "\\" + fc gp.Clip_analysis (fc, clipfc, outname) fc = fcs.next() Batch Batch processing Branching Branching based on conditions Delayed Delayed processing Can Can run in Toolbox or outside ArcGIS ...
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