Category Archives: Resource

Mapping Voting Rights Act Section Five Locations

This summer, a couple of us in the DSSC have decided to sit down and learn Leaflet & D3. We'll post some of the maps we make in the blog throughout the summer.

I'm grateful to Peter Leonard, the Librarian for Digital Humanities Research at Yale for getting me started on Leaflet at the NYPL Maps Hack 2013 organized by NYPL Labs.

As an exercise, I decided to map out the places no longer covered by the recent Supreme Court decision (PDF) on section four of the Voting Rights Act.

I took the tables on the Dept of Justice section 5 covered jurisdictions page, joined them together with boundaries from the US Census Bureau's TIGER/Line, simplified the shapefiles in QGIS (removed several fields too), exported to GeoJSON and brought the layers into Leaflet.

The map is sitting at a temp location until the bugs get worked out and we can include the maps in CU Spatial blog posts.

As you can see, it's fairly straight forward and includes some modified (simplified?) code from tutorials on the Leaflet site. The color choices came from ColorBrewer.

One thing I think would improve the map a bit would be to be able to click on the word 'townships' in the legend and have it automatically zoom to Michigan since at the starting scale, both townships are difficult to see (same with the three NYC counties).

Eventually, I'll redo this map in D3 because it'll allow me to use a projection better suited for North America.

Eventually we'll put the data into the Spatial Data Catalog, but for now I'm including a link to zip file containing both the shapefiles & geojson layers without proper metadata and a "use at your own risk" disclaimer. If you use it and find any mistakes, please let us know!

New ESRI Virtual Campus courses

esri-logoElelven new ESRI VC courses were added to the available list.

The self-pased courses on the list are free for all current Columbia University students, faculty and staff.

Here are the new courses

  • Advanced Techniques for Cartographic Representations (for ArcGIS 10)
  • Basics of Map Projections (for ArcGIS 10)
  • Building Models for GIS Analysis Using ArcGIS 10
  • Getting Started with Cartographic Representations (for ArcGIS 10)
  • Getting Started with Linear Referencing (for ArcGIS 10)
  • Linear Referencing Using ArcGIS 10
  • Mobile GIS: Creating Data Collection Applications Using the ArcGIS API for iOS
  • Mobile GIS: Getting Started with the ArcGIS API for iOS
  • Python Scripting for Geoprocessing Workflows (for ArcGIS 10)
  • Working with Annotation Using ArcGIS 10
  • Working with Coordinate Systems in ArcGIS 10

See the DSSC ESRI Virtual Campus courses page for a complete list of available courses and more information on registration.

New ESRI Virtual Campus courses

esri-logoThere are around 60 self-paced web courses available from ESRI to help learn GIS topics, concepts and ArcGIS software.

The courses on the list are free for all current Columbia University students, faculty and staff.

Some of the newer courses recently added are

  • Basics of Python (for ArcGIS 10)
  • Creating 3D Data Using ArcGIS 10
  • Distance Analysis Using ArcGIS 10
  • Managing Lidar Data in ArcGIS 10
  • Performing Spatial Interpolation Using ArcGIS 10
  • Using Raster Data for Site Selection (for ArcGIS 10)

See the DSSC ESRI Virtual Campus courses page for a complete list of available courses and more information on registration.

Using OpenStreetMap XML data


OpenStreetMap is a great resource mostly user created and maintained. The data is free of charge and there are several ways of accessing the data for use in a GIS project.

One of the easiest and quickest ways is to download data from CloudMade in shapefile format, but occasionally not all of the features shown in OpenStreetMap are available in the shapefile download.

An alternative is to download the OSM XML data, open it in QGIS, and if needed, export to shapefile.

To do this, open QGIS and under the Plugins menu, select Manage Plugins and turn on the OpenStreetMap plugin. If it’s not there then you will have to add it from Fetch Python Plugins.

The plugin allows for viewing downloaded OSM XML data, downloading large scale areas directly, and uploading edits you’ve made (account required).

Click on the Load OSM from file icon and navigate to the downloaded OSM XML layer.

Put a check mark next to the fields you want to create (these will only populate if the information is encoded). Keep a check mark next to Use custom renderer if you want to symbolize your data similar to the OSM scheme.

If you need to work with any of the features in shapefile format, right click on a layer and select Save vector layer as, and choose ESRI shapefile from the Format pull down menu if not already selected.

And that’s it!

ArcGIS 10 Available in the DSSC

ArcGISSplashScreenArcGIS 10 is now available on all PC’s in the DSSC including the EDS lab.

We’re still making some minor tweaks to the display and adding some toolbars like XTools Pro, which you’ll see sometime over the next couple weeks but overall it’s ready to use.

All CUIT lab machines still have ArcGIS 9.3 so if you need the old version, it’s available at least through the fall semester.

NYPL Map Rectifier


 NYPL has a new toy tool for rectifying digitized historic maps from their collection called the NYPL Map Rectifier.

After creating an account, browse through the various maps and collections, choose a map to rectify, clip or mask the image, and finally export out to either a KML (for Google Earth) or a WMS base URL for use in a GIS software. Some maps have the option to export into either PNG or TIF formats as well.

There is also a vectorize option for a few of the rectified maps (I didn’t see this option on most maps, I’m guessing because it’s still in beta). For these, the vector layers can be downloaded in several formats including shapefile.

NYPL has also created a site called Relief Map Warper and has uploaded maps for Haiti which after georeferencing, the maps will become available in Open Street Map for tracing, and also made available for use on the ground by relief workers. I highly recommend joining and helping out if you can.



Spatial Data Server Available in The DSSC!

We are in the process of implementing an ArcSDE installation for the distribution of many of our larger datasets.  The server is now online and we have several layers available, including Orthoimagery, Street files, World-wide DEMs and other raster datasets.  Right now access is only available from the DSSC and EDS labs. To access the layers you need to use an ESRI .lyr file, we have created one for each dataset and they can be downloaded from the CU Spatial Data Catalog.  These datasets can be viewed quickly and you can make extractions limited to your area of interest.  We will be adding more layers in the very near future.

Latest edition of MapPluto Now Available

We now have the latest version of the New York City Planning Tax Lot Layers; MapPLUTO 09 V1 is here and includes data updated through Spring of 2009.  MapPLUTO models tax lots throughout New York City. This dataset represents a compilation of data from various government agencies throughout New York. The attribute data pertains to tax lot and primary building characteristics and information related to administrative and political districts for each tax lot in New York City. The underlying geography is derived from the Department of City Planning’s Tax Block and Tax Lot Base Map project.

The datasets are only available in the EDS lab during lab hours.

New datasets from ArcAtlas

This summer we acquired the 1996 ArcAtlas: Our Earth collection from ESRI.  The atlas features dozens of datasets representing a wide ranging array of features, including climatical, geological, biological and political characteristics as well as physical facilities.   We have merged most of the ArcAtlas layers to create world-wide coverages, and these new datasets are available for download from the CU Spatial Data Catalog.