Cultivating Spatial Intelligence
Sources of Spatial Data
Most projects begin with a search for base data. It is easy to find spatial data on the web and in the GSD GeoData Collection, but depending on the what you need to represent, some data are easier to find than others. This lisiting will begin with a few sure-fire sources of data that you can use to build a contextual dataset for a city. We will then work up to strategies for finding more detailed data. One thing to always keep in mind: since you are going to invest time in pulling data together to study a place, you should organize your data well, and put it away in our GSD data collection so that others can build on what you have done!
- Getting Started with ArcGIS at the GSD.
- Understanding GIS Data and Metadata Discusses some of the formal concepts useful for interpeting and evaluating GIS Data.
- Spatial Data Structures and Formats. discusses and compares the various waus that GIS data are structured and exchanged.
- Organizing Spatial Data for Keeps
- What is ArcGIS
- Exploring Geographic Data A tutorial with a nice sample dataset.
- A very good list of data links form the Harvard Center for Geographic Analysis
Discovering Geographic Data
The great thing about geographically referenced data is that datasets compiled by independent agencies can be combined together and will align, spatially in a coherent way. GIS data, in additon to representing things graphically, records attributes reflecting information that is critical to understanding what things are. Discovering these resources can be as easy as doing a web search in Google or some such tool. Most cities of any size will have an official web site. Many now have sections of their web sites focused on Geographic Information Systems (GIS.) The likelihood of your finding free information about a particular area is usually proportional to the importance of that area to a government agency, and the willingness of that agency to make that information available. Un fortunately many governments around the world like to lock up their information so that only favored people can have the advantage of the best information.
Organizations that have a lot of information to keep track of typically do not use computer aided drafting (CAD) tools to manage their data. Database tools such as GIS are better able to deal with very large datasets and they are deeper in terms of being able to attach meaning to representations. GIS is also more flexible in accommodating real world coordinate systems. Luckily it is not difficult to convert GIS data to CAD formats.
Exploring GIS Data
Lets say you find some GIS data. It is a bunch of files. How do you look at it? This is where you need to start learning about how to use GIS. At the Graduate School of Design, our primary GIS tool is ArcGIS. You can find all of the documentation including some introductory tutorials about GIS in the GSD's GIS Manual Documentation Page. The key to understanding GIS data once you have opened it in a GIS, is to zoom in on details, and to examine the Attributes for the features or cells. For a good tutorial on exploring GIS data and metadata, see Exploring Geographically Referenced Data
General-Purpose GIS Data Resources on the GSD Network
Every project needs to begin with a study of the overall context. Data such as general shorelines and transportation. The easiest way to begin your gis database is with the collection of data that shops with ArcMap software. For a detailed description of building a contextual database for anywhere, consult the GSD On-Line Manual Page Beginning your GIS Database
ESRI Maps and Data
ArcGIS ships with 6 CDs containing hundreds of layers. These are handy for making maps, but also for general reference. The ESRI Data CDs can be found on the GSD network in L:\public\geo\esridata_9 Click here for a listing of the layers available on these CDs
OpenStreentMap The People's Map
The OpenStreetmap is a project that engages the public in the project of developing digital map data comparable with Google maps. The great thing about this project is that the data are freely available for applications outside of the web browser -- so, for ecample you can download GIS databases of teh openstreetmap data from GeoFabrik Web Site
The Harvard Geospatial Library
We can be proud that our own Harvard Library Digital Initiative has a collection of thousands of geographic datasets and images that can be seartched and downloaded through the with Tufts Open Geo Portal. This portal is amazing!! In addition to Harvard's resources, it also includes data frm MIT, Tufts and others!
Data from National and International Mapping Agencies
As our quest for data becomes more specific, the next most reliable source of data are national and international mapping agencies. Some of these public service agencies are very secretive or charge exorbitant prices for their data (for example, the British Ordinance Survey and its descendants around the world) which is a shame. But other agencies set a good example, For example:
Elevation Data The US Federal Government has very good information of a level of detail. You can find loads of useful information, including low cost aerial photography for the entire united states, at The National Map Viewer and Download Tool. is a new and growing source of information regarding terrain and land cover information, nationwide, and aerial photography for selected areas.
Global Terrain Information: can be downloaded from THe USGS Distributed Archive Center.
Bathymetry Data: For U.S. coastal bathymetry, check out The NOAA Estuarine Bathymetry download site.
A world-wide bathymetry dataset has been compiled by The General Bathymetric Chart of the Oceans (GEBCO) Their data is aviable for download from British Oceanographic Data Centre. Though this process is a bit convoluted and poorly documented. Users on the GSD network are encouraged to use our local copy of the GEBCO Bathymetry dataset with the GridView extraction sodtware located in goliath://geo/gebco_worldwide_bathymetry.
A technical tutorial on downloading and transfroming elevation data is covered in more detail on the web page, Digital Elevation Models.
More Global Sources
A good Source of data for Europe and Africa is found at The United Nations Environment Program GIS Data Bank.
A vast amount of information about places can be found in the form of digital images, either scanned maps or digital aerial photographs. Many sources of these are discussed on the The GIS Manual Page on Geographic Images Some of these images may have imbedded georeferencing information that allows it to be aligned with other data in the GIS. If not, then images may be georeferenced using techniques discussed on the Georeferencing Images.
The GSD has Google Earth Pro installed on our lab computers. The pro version accesses the same imagery as the free version but lets you download imagery at much higher resolution (using the File>Save>Image option. Although these images are not georeferenced, a trick for georeferencing these images very precisely is discussed on the page. Georeferencing Images and CAD Data.
Harvard Map Collection
The Harvard Map Collection has hundreds of thousands of maps and atlases. They will help you find maps and these may also be scanned. The Map Collection also has a lot of digital information and you can set up an appointment to consult with their digital data specialist.
State and Provincial Agencies
The more detailed the information you want, the less likely it is that you will find it for free on the web. At the state level, you may get lucky, and find a site like the Massachusetts GIS These days, even city governments are making their data available on the web. Find the GIS section of the state, city, or county's official web site.
Census Information for the US
Having set up your contextual framework, it will be very helpful to look at your area of interest in terms of demographics and housing. The GSD has the full line of CensusCD products accessible on the network. These make it easy to download census data from 1970 throu 2000, and to map any of thousands of geographical attributes as layers with your other gis data. For instructions on getting your census data, consult the manual page, . If all you need is basic population and housing information, your easiest source would be The ESRI Maps and Data CDs
It is highly reccommended that you read the page Understanding and Mapping Census Data at the GSD before fooling around with census data!
Locations of all Businesses in the US, Downloadable by Zip Code and Business Type
The Harvard Center for Geographic Analysis has licenses for a dataset for market research, ESRI Business Analyst which can be used to extract all sorts of marketing oriented demographics and information about businesses. COntact them to make an appointment to use this.
The GSD has 5 licenses for a spiffy CD business directory that permits you to select from all the businesses in the 2000 yellow pages, and map them in ArcMap. For exhaustive instructions for using this resource at your PC or a public computer, see the on line manual page entitled, Using the Business Directory.
Detailed Data of Local Interest
For local data, it helps to have connections. Studio instructors should cultivate their local connections well in advance of the start of their studio to try to obtain detialed local data. Obtaining local data involves a number of steps. First, you should have a clear idea of the types of layers that are desired(e.g. building footprints, trees, edge of pavement, property parcels, contours, aerial photography, etc.) Then think about what local agencies might have these data. Of course, you would look on the web to see if data are available easily -- or to find contact information of the probable custodians of the data. Then one would write letters or make phone calls. When requesting data you should be very specific about what you would like to find. If you simply ask for GIS data you are likely to get a file of zip code boundaries for the area in question. Of course, you should also ask for metadata! Click Here for a boiler-plate data request letter that you can tailor to meet your purposes.
The GSD GIS specialist does not routinely get involved in searching for data for students or studios, except in the case of core studios where the coordiators have made their needs known at least a month in advance. The demand for data searching is inexhaustible and often unreasonable. We will do our best to cultivate designers who understand how to compile their own resources.
The GSD's Geo Data Collection
Each term we try to gather together detaield datsets that have been gatherd for studios. This collection is stored on the shared network volume l:\public\geo. You can find descriptions of the datasets stored there in the Geo Catalog. If we don't happen to have the data you need, in our collection, or if it is not covered by one of the general sources listed above, then you will have to make some friends in the local GIS establishment in your area of interest. Please make sure to ask for metadata for the information you get, and please make sure that the data get archived in the GSD's data collection when you are finished!
Time Series Multispectral Satellite Images
The NASA Mission to Planet Earth project has produced nicely georeferenced series of relatively cloud free imagery covering the whole globe. The imagery, which can be downloaded from The University of Maryland Global Land Cover Faciltiy, is of fairly course resolution (30-60 meter cell size) but contains higher spectral resolution than most imagery, with a channel for infrared reflectance. These multi-chammel images can be tricky to work with, but if you are very patient, you can meld the various channels into useful graphical products and even do some classification of land cover and land use change, see Classifying Multispectral Images