GIS and Remote Sensing Lecture Notes
Introduction

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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 Seamless data or The National Atlas
   
2. 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."
3. 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?"
4. allows scenario testing
   ...if we raised the smokestack to 990 ft, would the effluent bypass the inversion layer?"  
   "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 (HEC-RAS flow model coupled with GIS layer of watershed)
   2. A forest fire plume model
      
6. aids visualization

• which improves understanding and pattern recognition
• & facilitates public participation in alternative scenarios
• & coordinates group decision making

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author: harbord@wlu.edu