Spatial data at MIT: Geographic Information Systems (GIS) Lab at MIT

1. Check that ESRI's ArcGIS software is installed on the computer.
2. Open ArcMap (the search tool does not run in other ArcGIS applications).
3. Check that the MIT Geodata Search tool is installed.

4. If you do not see "MIT Geodata" in the toolbar window, then right-click in the grey toolbar area to select it. If you do not see "MIT Geodata Repository" as an option in your list of tools then you will need to download it and follow the installation instructions.

Logging In

The MIT Geodata Repository is for academic use by current members of the MIT community only. In order to browse its holdings through this search tool for ArcGIS, one must first create an account. Accounts can be created and managed via the web at: http://libraries.mit.edu/gis/data/repository.html (You will need your personal MIT certificates in order to create or change your Geodata Repository account information.)

Basic Search

A basic search looks through select portions of the metadata for an exact match with the search string you type. Read the search hints below to learn about using wildcards. Check the spatial search check box to limit your search results to the area displayed in your ArcMap window. (You must already have data loaded into ArcMap for this to be effective.)

Boston search:

choose the search type "keyword"
enter the search string "Boston"
click the search button

Boston search results:

Multiple Keyword Search

The Search dialog allows you to search using multiple criteria. For example, if you would like information on property boundaries in Boston, you might enter "Boston" and "Parcel" in the keyword search box.

Boston parcel search:

Boston parcel search results:

A search looks through select portions of the metadata for an exact match with the search string you type. Read the search hints below to learn about using wildcards.

Limited Geometry Search

You can limit the search results to data layers that have a particular geometry (point, line, or polygon) or to rasters (e.g. images, digital elevation models). Check the box and choose a geometry to limit your search results. For example - cites represented as points indicate location, whereas cities represented as polygons represent location and area covered.

Search for Cities:

Cities search results:

Search for Cities and Point geometry:

Search for Cities and Point geometry results:

Limited Area Search

You can use the spatial search check box to limit your search results to the area displayed in your ArcMap window (you must already have data loaded into ArcMap for this to be effective).

Keyword and limited search area:

Keyword and limited search area results:

Search Map Area

This button lets you look for data covering a specific area, without using any keywords. This spatial search checks the bounding box (east-west and north-south extent of the dataset) of your ArcMap data frame and returns results that cover the same area and have a similar size bounding box. This can be very helpful when you know the area you are interested in, but are not sure how something may be described, spelled, or if it uses special characters. For example - location name changes like Bombay vs Mumbai, or different descriptions used to describe something like energy vs power.

Limit search area:

Limit search area results:

If you have no data in the window you will get a warning that no layers are present and a US States and a World Countries layer will automatically be added to your ArcMap window.

You can use these layers as reference data. Zoom in to the area where you want to search, then click the Search Map Area button again to re-run your search.

The Spatial Search option will eliminate datasets that cover areas much broader than the extent of your data frame. For example, if you have the city of Cambridge, and not much more area, in your window, the search will return statewide datasets but won't return datasets of the entire United States. Because the United States extends to the west of the 180 longitude line, United States datasets will appear on searches around the world.

If you have start with a layer with no projection information (or projection is 'undefined'), the search will not run. If you know the projection of your files, use ArcToolbox to define the projection of the data layer, or use the Data Frame Properties menu to add the projection information to the Data Frame. On the Data Frame Properties form that appears, select the Coordinate System tab. Change the projection from "Unknown" to the correct projection. All data in the MIT Geodata Repository have defined projections. The Spatial Search tool will always recognize these.

Search Results

Results of your search and the number of records found will appear in the search results dialog box.

Use your mouse to click on the record of interest then click the "view metadata" button to read the metadata, in FGDC format, in your default web browser.

To add the selected layer to ArcMap, click the “add selected layer to map” button.

Only one layer can be selected at a time. Click the "Search Again" button to perform a new search. Once the data is added to your view you can analyze the data using ArcGIS tools.

Metadata

Metadata is key information regarding the capture, creation, copyright, distribution, scale, projection, attributes, keywords and other details of data. The metadata file is important for understanding the data, documentation and source citation. Many of the datalayers in the MIT Geodata Repository have specific licensing restrictions, which can be found in the "use constraints" portion of the metadata.

Working with the data from the Geodata Repository

Once a spatial data layer is added to ArcGIS, you have the ability to analyze it using any tools in ArcGIS. You can access the same data layers, and the way you have symbolized them, in your ArcMap Document, from any computer on the network with ArcGIS software.

If you need to edit the data you must first export it into a workspace where you have read/write permissions. It is recommended that you only export your area of interest to keep the file size small.

To save your shapefile, right click on the layer name in the table of contents. Click "Data" -> "Export Data".

General Search Hints

Wildcards
An asterix (*) will work as a wildcard for multiple letters. An exclamation (!) will work as a wildcard for a single letter.

Examples:
"*parcel*" could retrieve parcel(s) and land parcel(s)
"wom!n" retrieves woman and women

Don't make your search too narrow :
If you can not find the file you need using the Advanced Search, you may need to be less specific. For example:

If you search for "road*" and "MA", you will only find Massachusetts roads, whereas US road files would also contain Massachusetts roads.
If you are looking for data for another country you may want to start with keyword = "world", then narrow your search using the spatial selection tools
Good data for specific area can sometimes be found as part of global or country level dataset.

Browse all data button
The Basic Search screen has a browse all data button, which allows you to see a complete list of the available data in the MIT Geodata Repository. If you cannot find desired data by using search parameters, try scanning this list to search all available options.