Geospatial
Visualization

School of Architecture

Dr. Timothy Norris
tnorris@miami.edu

Christopher Mader
cmader@med.miami.edu

Image: D.M. Swart
Artistic cartography:
creative ways to peel the globe

Coordinate Reference Systems

• Datum
• Geographic coordinate system
• Projected coordinate system
• Geospatial data must have: datum + geographic coordinate system
• Projected coordinate systems are optional
  (but needed for measurement)

Datum

• Center of the earth?
• That which is given?
• Ellipsoid
  mathematically defined surface approximating the shape of the earth
• Geoid
  surface of the earths gravity field - approx sea level

Geographical Coordinate Systems

• Latitude and Longitude - spherical coordinates
• Very common, but cannot be used for measurement
• Things to remember:
  • EPSG - European Petroleum Survey Group
  • WGS 84 - most common datum globally - EPSG:4326
  • NAD 83 - most common datum in the United States - EPSG:4269

Projected Coordinate Systems

• meters or feet - Cartesian coordinates
• Used for measurement and mapping
• Things to remember:
  • Projected Coordinate Systems are specific to the area being mapped
  • In the USA: the "State Plane System"
  • Around the Globe: the "UTM Grid"
  • For web based mapping systems
    WGS 84 Web Mercator - EPSG:3857

Projected Coordinate Systems (more)

Projection Surfaces

Tissot and Distortion

Tissot's ellipses on an unprojected (lat/long) earth

Universal Transverse Mercator - UTM

The 60 UTM coordinate system zones, each divided into north and south halves at the equator

State Plane

Other Projections

Also see: https://map-projections.net/imglist.php

Getting Some Data (exercise #1)

• Create project - do good data management!!
• Goto the Miami-Dade Data Portal
  • Find the Contaminated Sites data set
  • Note anything interesting about the context of this data.
  • Look for projection information. What EPSG? Other information?
  • Download the data as a CSV file (save in a project folder).
• Open the CSV in your GIS platform of choice
• Find out how to "Create Points" for x/y (lat/lon) data
• Perhaps google "create points" and the name of the GIS platform ... ArcGIS Pro/QGIS
• Create points for the Latitude/Longitude columns
• Create points for the X_Coordinate/Y_Coordinate columns

Getting Some Data (exercise #1)

• Re-project the data to correct state plane
• re-project by "export" (right click on layer name and look for "export" or "data > export")
• pay attention to CRS/projection - explore!! (google is your friend)
• datum NAD83 (2011) feet
• find correct state plane CRS for Miami-Dade (use search filters wisely)
• With both the CRS information and the map visible, send a screenshot to me

Getting Some Data (exercise #2)

• Create project - do good data management!!
• Goto Open Street Map (OSM)
  • look around, find a place with not too much data (Key Biscane for example)
  • Locate and click the "Export" button
  • Make your selection small
  • Click the large "Export" button
• Open the downloaded OSM data in QGIS
• In "Plugins" menu install the plugin "QuickOSM"
• Once installed, in "Vector" menu select "QuickOSM"
• Load the "map.osm" file (copied from your downloads to your project data directory)
• Be patient, it may take a while

Getting Some Data (exercise #2)

• Explore the OSM data
• Look at the attribute tables for each layer that was imported (points, lines, polygons)
• With the OSMFile (polygon) layer selected, select filter from the "Layer" menu
• create a filter where "Building" != ''
• Export the polygon layer to a shapefile (in your data directory with a good name)
• Use a projection you feel is appropriate
• Note that the new layer is *not* a memory layer
• Open the shapefile in ArcGIS Pro
  • Create project - do good data management!!
  • Add the shapefile to the map
  • Right click the layer, choose symbology ...
  • Use "Unique Values" with the column "buildings"
• With the map visible, send a screenshot to me