GIS and Remote Sensing Lecture Notes
Introduction


What does a GIS do?
  1. collect, store, organize, and distribute data
    common to see data files in the 10-100 megabyte range, up to gigabytes of remote sensing data.
    USGS National Map or download older, small scale data files
    USGS Earth Explorer (discover and download)
  2. allows exploration of  relationships among data layers
    "...high yield forage grass is most common on which rock types?"
    "...how does population density relate to water quality?"
  3. criteria matching
    "I need to find a place for an outdoor recreation specialist at the Forest Service that is...
        on public land
            with gentle slope
                with permeable soils (for the the privy!)
                    possessing nice views of the Blue Ridge
                        amongst shade trees
                            and within 50 m of a canoe-able river...
    so that she can build a campsite there."
  4. allows scenario testing
    ...if we moved the new landfill, would it be farther from most domestic water wells? Would it be more visible?"  
    "how about moving it to here?... or here?..."
    CommunityViz a commercial ArcGIS extension to test land use scenarios
  5. serves as a data handler for other analyses
    e.g., passing geologic and topographic data to an erosion model of the Appalachians, or passing water quality and groundwater levels to a groundwater flow model
    these are typically written in other languages (C++, Fortran, etc) that can access the GIS.
    1. A flood inundation model (GIS holds the data couples with hydrologic model, and displays results)
    2. A forest fire plume model uses ArcGIS to locate fires from public data and incorporate in calculations)
  6. aids visualization
  7. models environmental processes and outcomes
    forward modeling - input known conditions to predict outcomes
    inverse modeling - input known outcomes or conditions to understand causes
    See for example Geostatistical modeling in ArcGIS help

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author: harbord@wlu.edu