The Geographic Information System Tool (GIST): A New Tool for Visualizing Geographic Data

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The Geographic Information System Tool (GIST) A
New Tool for Visualizing Geographic Data

• Alison M. Eyth, Prashant Pai
• MCNC Environmental Modeling Center
• October 22, 2002

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PAVE Limitations

• Graphics are written in X-windows / Motif (not
  good for PCs)
• Must be compiled separately for each platform
• Only a few maps provided (states, counties,
  roads, rivers), with limited rendering styles
• Cannot plot data in polygons only rectangular
  grid cells and limited facilities for
  observations
• Plots accessible over web only as static images

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Current GIST Features

• Create maps of points, lines, polygons
• data from Shapefiles or ASCII format
• Data sets drawn in layers,
• can be moved up, down, sent to top or bottom,
  hidden/shown
• Configurable data object styles
• colors, line thickness, point symbols
• Set map projection / ellipsoid
• Probe data attributes
• Thematic mapping
• Querying
• Display mouse coordinates, zoom, overview, print

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Potential New Data Types

• Emission inventories and surrogates
• Air quality and meteorological observations
• Slices of regular grid air quality model results
• Variable grid model results
• Multimedia model results (already have prototype)
• Water quality model results
• Flight paths
• Can already support points, lines, polygons from
  any type of shapefile (e.g. population data, land
  use)

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Behind the Scenes of GIST

• Java program
• Portable across platforms
• Object-oriented / extensible
• Runs as desktop application or over web as applet
• Uses JLooxGIS class library (www.loox.com)
• Basic plotting of points, lines, polygons on map
• Coordinate transformations
• Zooming
• Printing
• Panning / map overview
• Layer control
• Not open-source

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Layer Library

• Maintains layers loaded between GIST sessions
• Friendly names can be specified for data sets
• Separates file format from objects in display

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Probing to show Data Attributes
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Thematic map and Layer Options
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Query Results as Map and Table
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Future Directions

• Enhancements dependent on funding source
• Currently MCNC funded proprietary software
• Animation (within data set and across data sets)
• Scripting language
• Formula language (like PAVE)
• Save images to graphics formats
• Show satellite pictures and DTED
• Save images and data to files
• Improved probing, overview, queries, resizing
• Save configuration and restart using it
• Data subsetting / improved memory management