GIS fundamentals by bjb17276

VIEWS: 128 PAGES: 55

									USC February 11th, 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
 Current issues and research directions
                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
    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
     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).
   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).
         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)
      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”
          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.”
       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
Major GIS-Only Journals

 International Journal of Geographical
  Information Systems
 Cartography and GIS
 Transactions in GIS
 Geospatial solutions
 Geoworld
    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)
    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
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.
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.
    Alternative georeferencing

 Local grids
 Place names
 Street address (123 Main St.)
 Raw geographic lat./long.
 Internet URLs
                GIS Capability

   A GIS package should be able to move
    between
       map projections,
       coordinate systems,
       datums, and
       Ellipsoids
   And do geocoding
Basics II: Features vs. Fields
Arc/node map data structure with files
Grids as fields

             Missing data
             Multi-resolution
             Mixed pixels
             Drop out
             Interpolation
           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.
    Basics III: Some common
              formats
 SHP, E00
 DXF
 GeoTIFF
 Img
 VPF
 DRG, DEM, DOQQ
 TIGER/SDTS
             Data resources

   NSDI clearinghouses
   www.geocomm.com GISDataDepot
   Geography network
   Terraserver
   Alexandria www.alexandria.ucsb.edu
   Geospatial One Stop
   National Map
   GDT, ESRI etc.
             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.
        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.
                 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
  Basics IV: Data structure
   transformation errors




E.g. scanning and fat lines
Transfer Standards
             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.
    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
          OGC Initiatives

 Testbeds
 Pilot projects
 Interoperability planning studies
 Interoperability experiments
 Uses working groups: 256 active
  members, university, government,
  business: world wide
              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
        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)
        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.
                         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
                     ArcView
Versions 1-3, 3.1-3, 8.x
PC Windows
Avenue
Web links
Map Objects
Extensions
IMS: Internet Map Server
                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
                        GRASS



First UNIX GIS
Developed by Army
Corps of Engineers
UNIX functionality
Many unique functions
Free until recently
Many data sets
Baylor University
                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
       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. Ahern
                            Hunter College - CUNY
    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
    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
                   Data

   NYCMap
       Orthophotography
       Planimetric maps
 Thermal imagery
 LIDAR imagery
 GPS data
                            NYCMap
                                     30 cm resolution
                                     orthophotography




Planimetric map -
absolute spatial accuracy
of half a meter
LIDAR
Thermal imaging


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

A glimpse of some current research
 Sensor networks
 Mobile GIS
 Location-based services
                   Wireless Sensors




moat.nlanr.net/NATimes/ NAT.1.2/wireless.html
http://www.enterprise.mtu.edu/gwse/
Kris Pister, Berkeley
UCLA CENS
UCSB Prototype Wearable Computer
Field Test Prototype:
YAH, Image view, text off, perspective on
   Computer vision for hand gesture recognition
        (Source: Mathias Kolsch, UCSB)

head-mounted display
head-mounted camera
Location-based web search
Keith’s Daily Commute
     Consequences of Location-
            awareness
 Navigation assistance in real time
 Real time analysis and adaptive
  sampling
 Real human agents: “lifelines”
   (Huisman and Forer, 1998; students in Auckland)

								
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