Massachusetts Institute of Technology - Department of Urban Studies and Planning

SP.757 - Digital Imaging Seminar - In-Lab Notes, October 28, 2010

Geographic Information Systems (GIS) and Map Mashups

Joe Ferreira - http://mit.edu/11.520/www/labs/sp.757_labnotes_10oct28.html

Introduction

Examine digital imagery and mapping tools that allow geography and geospatial relationships to be visualized and analyzed
Borrow basic GIS exercise from 11.188 (Urban Planning and Social Science Laboratory)
- an undergrad subject that satisfies the undergrad lab requirement
  - Taught together with 11.520 - See class website: http://mit/edu/11.520/www
- Create a thematic map of Cambridge census data showing areas with high/medium/low income
- Overlay the map onto Google Earth
Experiment with Google Sketchup to draw 3D objects, paint them using photos, and overlay them onto Google Earth

Online mapping tools

Basic street maps and directions:
- Mapquest: http://www.mapquest.com
- Google maps: http://maps.google.com
- Microsoft Bing maps: http://www.bing.com/maps/
State GIS agencies (that build, standardize and share GIS basemaps and layers)
- MassGIS: Main site: http://mass.gov/mgis/
- Data layers and download info: http://mass.gov/mgis/database.htm
- Online Mapping at MassGIS: http://www.mass.gov/mgis/mapping.htm
Distinguish between map publication, single purpose apps, and geoprocessing (interactive spatial analysis)
- Contrast these online mapping sites with a comprehensive desktopapplication
Intro to geographic information system (GIS) software
- Use ArcGIS from ESRI: http://www.esri.com

Illustrate use of ArcGIS to do 11.188 lab exercise #1: http://mit/edu/11.520/www/labs/lab1
Key ideas regarding data model and GIS tools for 'geoprocessing'
- Vector ('connect the dots' boundary) model of objects in space
  - Links between objects on map and attributes in table
- Raster (digital photo as grid cells) model of space and its contents
  - orthophotos and coordinate systems

Geospatial Web Services (different from 'online mapping')
- Define Application programming interfaces (APIs) that facilitate interoperability across machines
- Web service protocols can support geoprocessing within 'software as a service' environment

MassGIS web services homepage: http://lyceum.massgis.state.ma.us/wiki/doku.php)
Examples: consider the following URLs to request snippets of road maps as PNG-images from MassGIS

http://giswebservices.massgis.state.ma.us/geoserver/wms?dpi=120&request=GetMap&layers=GISDATA.EOTMAJROADS_ARC&srs=EPSG:4326&bbox=-71.1,42.35,-71.0,42.37&width=1000&height=300&format=image/png&service=wms&transparent=true

http://giswebservices.massgis.state.ma.us/geoserver/wms?dpi=120&request=GetMap&layers=GISDATA.NAVTEQRDS_ARC&srs=EPSG:4326&bbox=-71.1,42.35,-71.0,42.37&width=1000&height=300&format=image/png&service=wms&transparent=true

The URLs are 'RESTfull' protocols that use web services to request and obtain maps and GIS resources

REST stands for REpresentational State Transfer within service-oriented architecture discussions

Do you recognize the meaning of the parameters? Play with the values...

http://giswebservices.massgis.state.ma.us/geoserver/wms?

dpi=120&

request=GetMap&

layers=GISDATA.EOTMAJROADS_ARC&

srs=EPSG:4326&

bbox=-71.1,42.35,-71.0,42.37&

width=1000&

height=300&

format=image/png&

service=wms&

transparent=true

EPSG = European Petroleum Survey Group

4326 is the EPSG code for the World Geodesic Datum of 1984 (WGS84)

26986 is Mass State Plane Coordinates, NAD83 meters

Note that some services only produce maps at particular scales

Otherwise, get xml-tagged error message

Recognize utility of open standards for interoperable geospatial web services

The previous examples used the web mapping service (WMS) protocol

from the Open Geospatial Consortium

http://www.opengeospatial.org

Map mashups

Check out these sights:
- Zillow: housing price estimator ('Your edge in real estate')
  - http://www.zillow.com/
  - Results for 200 Putnam St, Cambridge:
    - http://www.zillow.com/homes/200-Putnam-st,-cambridge,-ma_rb/
  - How are maps and tables stored, queried, assembled? what is the business model?
- Walk Score: rating addressess for local walkability:
  - http://www.walkscore.com/
  - boston 'hot spot' map: http://www.walkscore.com/MA/Boston
  - Results for 200 Putnam St, Cambridge
    - http://www.walkscore.com/score/200-putnam-st-cambridge-ma
  - How are maps and tables stored, queried, assembled? what is the business model?
    - Transit calculation uses google transit API (discussed below)

More online mapping and geoprocessing sites:
- Traffic maps (and the layering of public/private services underneath them)
  - Washington DC traffic (Maptuit/SmartRoute/Westwood-One site via Washington Post):
  - http://www.washingtonpost.com/wp-dyn/content/metro/traffic/
- Government supported efforts to facilitate GIS data access
  - Geospatial OneStop (Portal for Federal GIS data): http://geodata.gov/
  - NCAR weather data
    - Weather modeling example at the National Center for Atmospheric Research (NCAR):
    - MM5 (mesoscale model, fifth-generation): http://www.rap.ucar.edu/weather/model/index.php?model=gfs
  - The (US) National Map
    - http://nationalmap.gov/(cover page)
    - http://nationalmap.gov/viewers.html (homepage for map viewer)
    - USGS-led effort at coherent, cross-agency national map layers

Tagmaps (Yahoo maps + Flikr photos)
- http://tagmaps.research.yahoo.com
- Choice and size of labels are determined by local frequency of keywords in user-provided photos
  - Using algorithms from Stanford PhD thesis

Handling Orthophotos and High-Resolution Imagery in Photoshop

Photoshop focuses on image manipulation rather than processing based on coordinate systems and geographic proximity
However, Photoshop has some tools that facilitate the use and overlay of large, geographically referenced images
Lesson 13 of the Adobe CIB Photoshop CS3 book has illustrations and is available in the class locker:
- http://web.mit.edu/sp.757/www/Photoshop/CIBCS3-lesson13-infographics/

Google Earth Exercise(Optional - just for fun!)

Start Google Earth:
- find your home town
- Explore navigation interface (zoom in/out, rotate and tilt, turn on/off buildings
Overlay WMS services on top of Google Earth
- Choose Add/.Image-Overly and use the following parameters:
  - Name: MassGIS-street-map
  - Link: use a version of the two MassGIS URLs illustrated above
    - First remove the EPSG and bounding box phrases since Google will fill those in
    - the width/height ratio must match your Google window or the map labels will be distorted
    - Try this URL for the major roads:
    - http://giswebservices.massgis.state.ma.us/geoserver/wms?dpi=120&request=GetMap&layers=GISDATA.EOTMAJROADS_ARC&EPSG:4326&width=600&height=480&format=image/png&service=wms&transparent=true
  - Refresh-tab: set "when" to be "after camera stops"
- The MassGIS server will send an image overlay of local streets that Google Earth places in the appropriate place
Explore "GeoModeling" with Google Earth and Sketchup
- In Google Earth, zoom in to the MIT campus
- Place a to-scale model of Eiffel Tower on Briggs Field
  - Choose Add/Network-Link and select this file:
    - Z:\athena.mit.edu:\course\11\11.520\data\sketchup\eiffel_08nov06_v1.kmz
    - Which is also visible in an online AFS class locker (http://mit.edu/11.520/data/sketchup)
- Keep Google Earth open and start Google Sketchup as well
  - Open the saved Eiffel Tower sketchup file in:
    - Z:\athena.mit.edu:\course\11\11.520\data\sketchup\eiffel_mit_08nov.skp
  - Click the "view your model in Google Earth" button (3rd from right side of tool bar)
    - The sketchup model will be placed into Google Earth in the same location as determined by SketchUp from the registered image that came from a Google Earth snapshot.
    - Some machines in the MIT labs will not allow this method of moving 3D models from SketchUp to Google Earth (do to file writing permission issuses). In that case, from Sketchup, choose File/Export/3D-Model and save your model to disk in KMZ format (zipped keyhole markup language, KML). Then open the file in Google Earth via Add/Network-Link.
- Turn on 3D buildings in Google Earth and examine the scale of the Eiffel Tower compared with the playing fields and MIT buildings
- Explore additional Google Earth and Sketchup capabilities - e.g., you can drape photos onto wire frame building models so the photos provide a realistic facade for the buildings
- Think about how Eiffel Tower model might be encoded for efficient and standard hand-off to Google Earth
  - Introduction to KML: http://code.google.com/apis/kml/documentation/
- For more information about downloading and using Google Earth and Sketchup see:
  - Downloading Google Earth: http://earth.google.com/
  - Downloading Google Sketchup: http://www.google.com/sketchup/download/
  - Geomodeling with Google Earth: http://sketchup.google.com/support/bin/topic.py?topic=13681&hl=en
  - How to place a Sketchup model in Google Earth: http://sketchup.google.com/support/bin/answer.py?answer=36241&topic=13681
Do Lab #1 from 11.520/11.188: http://mit.edu/11.520/www/labs/lab1/lab1.html
- Cambridge map showing streets and location of 1989 housing sales
- Shade thematically based on median household income
- Open attribute table and test link between map and table
- Save your map to a 'kmz' file that can be viewed on Google Earth

Created by Joseph Ferreira.
Last Modified: 27 October 2010 (jf)

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