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Introduction to Union Square GIS

Introduction to Union Square GIS. Chris Gist GIS Specialist The Scholars’ Lab Alderman Library http://www.lib.virginia.edu/scholarslab. What is the Scholars’ Lab?. The Scholars’ Lab is a collaboration between the University Library and Information Technology & Communication (ITC).

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Introduction to Union Square GIS

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  1. Introduction to Union Square GIS Chris Gist GIS Specialist The Scholars’ Lab Alderman Library http://www.lib.virginia.edu/scholarslab

  2. What is the Scholars’ Lab? The Scholars’ Lab is a collaboration between the University Library and Information Technology & Communication (ITC) UVa Library ITC Research Computing Support (RCS) Digital Scholarship Services

  3. Scholars’ Lab GIS • We collect, maintain and make accessible a large amount of spatial data • Local Data • Aerial Imagery • Elevation Data • ESRI Base Data • Misc. • Software Support • ESRI Products • MapServer • HTML ImageMapper • Hardware – GPS units

  4. What are our biggest problems in assisting patrons? • Finding good data • Importing data • Moving data • Saving your work

  5. The Digital Data Fallacyas defined by Chris Gist “If I can imagine it, a data set exists in the proper format, free of charge, and available for immediate use at the touch of a button.”

  6. Locating Data: Overview • Decide coverage area and data needs • Survey available data • Adjust expectations • Acquire, create and standardize • Analyze

  7. Issues for Data • Currentness • Projections • Accuracy • Scale • Metadata

  8. Date • Lags between survey and production • Cost of constant updates are still prohibitive • Most GIS data has been produced within the last 10 years • Historical data is not being created in significant amounts

  9. Projection System • Also known as “coordinate system” • Dependent upon: • Local standards • Uses and needs • Multiple data sources mean multiple projections

  10. Choice of projections…

  11. Accuracy • Accuracy is a relative term • Often dependent upon use • National Map Accuracy Standards • Accuracy report may be descriptive rather than quantitative

  12. Accuracy: Census Streets Data

  13. Accuracy: City Planning Data

  14. Scale & Resolution • Ratio between dimensions of map and real world • Large scale: “big picture of small space” • Small scale: “little picture of big space” • 1:63360 • “1 inch to the mile” • 5280 feet = 63360 inches • “1 meter/pixel” • For GIS data this refers to the source

  15. Scale: 1:5 million

  16. Scale: 1:100,000

  17. Larger Scale

  18. Smaller Scale

  19. Overlaid Together

  20. Resolution: 1-meter/pixel

  21. Resolution: 1-foot/pixel

  22. Resolution: 6 inch/pixel

  23. Metadata • Data about data • GIS data Standards: • GML • FGDC • ISO • Information included (not exhaustive) • Originator • Usage • Attributes • Projection • Extent • Unfortunately, often not available

  24. Importing Data • Different Data Types • Shapefiles • Geodatabases • DEMs • Coverages • CAD • Images • Other proprietary formats (MapInfo) • ArcGIS directly “reads” many of these formats • ArcToolbox has converters for DEMs, CAD and Coverages

  25. Moving Data • Shapefile is a misnomer • Many spatial data layers are collections of files or directory and file collections • ArcCatalog is the best tool for dealing with spatial data • “Explorer” of ArcGIS Suite • Shapefile appears as one object • Only place shapefiles can be created • Can view metadata

  26. Saving Your Work • ArcMap Project • .mxd • Relative path • Export Map • Multiple image formats JPG, TIF, GIF, PDF • Vector Formats SVG, AI, PDF • KML • GML

  27. ESRI Virtual Campus • Online classes that teach general GIS theory and about how to use ESRI products. • Many free classes available to members of the UVa community • Recommended to increase knowledge in particular areas. • Less recommended to “teach yourself GIS” • http://fisher.lib.virginia.edu/reference/help/esri/virtualcampus/ • Available only on grounds or UVaAnywhere

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