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GIS fundamentals

USC February 11 th , 2004 Southern California Earthquake Center. GIS fundamentals. Keith Clarke Professor, UC Santa Barbara Director (UCSB) NCGIA. What I will cover. Basics of GIS How can GIS help me in my research? Some cartographic “roots” Where to go for more help

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GIS fundamentals

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  1. USC February 11th, 2004 Southern California Earthquake Center GIS fundamentals Keith Clarke Professor, UC Santa Barbara Director (UCSB) NCGIA

  2. What I will cover • Basics of GIS • How can GIS help me in my research? • Some cartographic “roots” • Where to go for more help • Current issues and research directions

  3. Defining GIS • Different definitions of a GIS have evolved in different areas and disciplines • All GIS definitions recognize that spatial data are unique because they are linked to maps (Space matters!) • A GIS at least consists of a database, map information, and a computer-based link between them

  4. What’s special about spatial? • Everything happens in geographic space • Primitive = f(x, y, z, t) • Tobler’s law • Geographical relations • Hagerstrand’s time-space geography • Makes search and query powerful

  5. Definition 1: A GIS is a toolbox "a powerful set of tools for storing and retrieving at will, transforming and displaying spatial data from the real world for a particular set of purposes" (Burrough, 1986, p. 6). "automated systems for the capture, storage, retrieval, analysis, and display of spatial data." (Clarke, 1995, p. 13).

  6. Definition 2: A GIS is an information system "An information system that is designed to work with data referenced by spatial or geographic coordinates. In other words, a GIS is both a database system with specific capabilities for spatially-referenced data, as well as a set of operations for working with the data" (Star and Estes, 1990, p. 2).

  7. Definition 3: GIS is an approach to science • Geographic Information Science is research both on and with GIS. "the generic issues that surround the use of GIS technology, impede its successful implementation, or emerge from an understanding of its potential capabilities." (Goodchild, 1992)

  8. Definition 4: GIS is a multi-billion dollar business. “The growth of GIS has been a marketing phenomenon of amazing breadth and depth and will remain so for many years to come. Clearly, GIS will integrate its way into our everyday life to such an extent that it will soon be impossible to imagine how we functioned before”

  9. Definition 5: GIS plays a role in society. Nick Chrisman (1999) has defined GIS as “organized activity by which people measure and represent geographic phenomena, and then transform these representations into other forms while interacting with social structures.”

  10. Sources of Information on GIS • The amount of information available about GIS can be overwhelming • Sources of GIS information include journals and magazines, books, professional societies, the World Wide Web, and conferences • GIS has Web Home pages, network conference groups, professional organizations, and user groups • Most colleges and universities now offer GIS classes in geography departments • ESRI’s virtual campus…..etc

  11. Major GIS-Only Journals • International Journal of Geographical Information Systems • Cartography and GIS • Transactions in GIS • Geospatial solutions • Geoworld

  12. Professional Organizations • GITA: The Geospatial and Information Technolgy Association (http://www.gita.org) • AAG: The Association of American Geographers. (http://www.aag.org) • CaGIS: Cartography and Geographic Information Society (American Congress on Surveying and Mapping) (http://www.cartogis.org) • ASPRS: American Society for Photogrammetry and Remote Sensing (http://www.asprs.org) • URISA: Urban and Regional Information Systems Association (http://www.urisa.org)

  13. GIS daily internet news/jobs • http://www.geoplace.com • http://www.giscafe.com • http://www.gis.com • http://www.geographynetwork.com • http://www.census.gov/geo/www/faq-index.html • http://www.geo.ed.ac.uk/home/giswww.html • http://www.lib.berkeley.edu/EART/abbrev.html

  14. Basics I: Coordinate Systems • A coordinate system is a standardized method for assigning codes to locations so that locations can be found using the codes alone. • Standardized coordinate systems use absolute locations. • A map captured in the units of the paper sheet on which it is printed is based on relative locations or map millimeters. • In a coordinate system, the x-direction value is the easting and the y-direction value is the northing. Most systems make both values positive.

  15. Coordinate Systems for the US • Some standard coordinate systems used in the United States are • geographic coordinates • universal transverse Mercator system • military grid • state plane • To compare or edge-match maps in a GIS, both maps MUST be in the same coordinate system.

  16. Alternative georeferencing • Local grids • Place names • Street address (123 Main St.) • Raw geographic lat./long. • Internet URLs

  17. GIS Capability • A GIS package should be able to move between • map projections, • coordinate systems, • datums, and • Ellipsoids • And do geocoding

  18. Basics II: Features vs. Fields

  19. Arc/node map data structure with files

  20. Grids as fields Missing data Multi-resolution Mixed pixels Drop out Interpolation

  21. Topology Matters • The tolerances controlling snapping, elimination, and merging must be considered carefully, because they can move features. • Complete topology makes map overlay feasible. • Topology allows many GIS operations to be done without accessing the point files.

  22. Basics III: Some common formats • SHP, E00 • DXF • GeoTIFF • Img • VPF • DRG, DEM, DOQQ • TIGER/SDTS

  23. Data resources • NSDI clearinghouses • www.geocomm.com GISDataDepot • Geography network • Terraserver • Alexandria www.alexandria.ucsb.edu • Geospatial One Stop • National Map • GDT, ESRI etc.

  24. Vectors and 3D • Volumes (surfaces) are structured with the TIN model, including edge or triangle topology. • TINs use an optimal Delaunay triangulation of a set of irregularly distributed points. • TINs are popular in CAD and surveying packages.

  25. TIN: Triangulated Irregular Network • Way to handle field data with the vector data structure. • Common in some GISs and most AM/FM packages. • More efficient than a grid.

  26. GIS and 4D • The missing t in (x, y, z, t) • Much interest in spatio-temporal dynamics, models • Only a few methods as yet, still research • Spatial modeling tools in few GIS, e.g. CA in IDRISI • Transaction-based problem solved in 2D e.g. Oracle Spatial

  27. Basics IV: Data structure transformation errors E.g. scanning and fat lines

  28. Transfer Standards

  29. GIS Data Exchange • Data exchange by translation (export and import) can lead to significant errors in attributes and in geometry. • In the United States, the SDTS was evolved to facilitate data transfer. • SDTS became a federal standard (FIPS 173) in 1992. • SDTS contains a terminology, a set of references, a list of features, a transfer mechanism, and an accuracy standard. • Both DLG and TIGER data are available in SDTS format. • Other standards efforts are DIGEST, DX-90, the Tri-Service Spatial Data Standards, and many other international standards. • FGDC issues metadata standards, and selected feature standards, e.g. raster profile • Efficient data exchange is important for the future of GIS.

  30. Issue #1 Interoperability • The Open GIS Consortium, Inc. (OGC) • Member-driven, non-profit international trade association • Leading the development of geoprocessing interoperability computing standards. • www.opengis.org • Issues standards-documents-does compliance testing

  31. OGC Initiatives • Testbeds • Pilot projects • Interoperability planning studies • Interoperability experiments • Uses working groups: 256 active members, university, government, business: world wide

  32. Active initiatives • Critical Infrastructure Protection Initiative, Phase 1.2 (CIPI 1.2)In Progress • Emergency Mapping Symbology, Phase 1 (EMS 1)In Progress • Land Information Initative, Phase 1 (LII-1)Initiated • OGC Web Services, Phase 2 (OWS-2)Initiated

  33. Selected past initiatives • Conformance & Interoperability Test & Evaluation, Phase 1 (CITE 1) • Geospatial Fusion Testbed (GFST) • Geographic Objects (GO-1) • Geospatial One-Stop - Portal Initiative (GOS-PI) • Multihazard Mapping Initiative, Phase 1 (MMI -1) • Object Domain Modeling Support (ODMS) Initiative (ODMS) • Open Location Services Testbed (OpenLS 1) • Web Mapping Testbed, Phase 1 (WMT 1)

  34. Analytic Tools and GIS Tools for searching out spatial relationships and for modeling are only lately being integrated into GIS. Most commonly used are map algebra (overlay), buffer etc. Statistical and spatial analytical tools are also only now being integrated into GIS, and many people use separate software systems outside the GIS. Real geographic phenomena are dynamic, but GISs have been mostly static. Time-slice and animation methods can help in visualizing and analyzing spatial trends.

  35. ArcGIS ESRI Redlands, CA Market leader PC and workstation remarkable functionality many formats supported Currently in version 8.1-3, 9 expected Versions 1-7 Arc/Info

  36. ArcView Versions 1-3, 3.1-3, 8.x PC Windows Avenue Web links Map Objects Extensions IMS: Internet Map Server

  37. AutoCAD MAP Windows all versions SQL DBF Access Extension to AutoCAD Menu-based Massive installed base Added grid, projection & topology support DB links good. 3D links good

  38. GRASS First UNIX GIS Developed by Army Corps of Engineers UNIX functionality Many unique functions Free until recently Many data sets Baylor University

  39. IDRISI: Idrisi 32 Developed at Clark University, Worcester MA Original in PASCAL, with open code Development uses a specialty Windows/DOS Spatial analysis/stats extensions

  40. Getting Started with GIS Case Study 3:GIS at the World Trade Center • How GIS helped in the rescue and clean-up operations after the world’s worst terrorist attack Contributor: Sean C. AhernHunter College - CUNY

  41. September 11, 2001, 4pm • “Get your staff together and start creating maps” • Hunter College’s Center for the Analysis and Research of Spatial Information (CARSI) called in to help deal with the aftermath

  42. WTC operations at Pier 92 • GIS support for firefighters, rescue workers, utility crews • 24 hours a day / 7 days a week support for 2+ months • 50+ GIS professionals

  43. Data • NYCMap • Orthophotography • Planimetric maps • Thermal imagery • LIDAR imagery • GPS data

  44. NYCMap 30 cm resolution orthophotography Planimetric map - absolute spatial accuracy of half a meter

  45. LIDAR

  46. Thermal imaging Thermal remote sensing data collected at the WTC on September 16. Source: Roger Clark, USGS, Open File report 01-0429

  47. GPS

  48. What next? A glimpse of some current research • Sensor networks • Mobile GIS • Location-based services

  49. Wireless Sensors moat.nlanr.net/NATimes/ NAT.1.2/wireless.html http://www.enterprise.mtu.edu/gwse/ Kris Pister, Berkeley UCLA CENS

  50. UCSB Prototype Wearable Computer

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