Category Archives: Web Mapping

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!

Converting Shapefiles to Google Fusion Tables using shpEscape

For anyone who’s tried to go from shapefile to kml and then upload that kml to Google Fusion tables, you’ve likely experienced the problem of all of your attribute fields being merged into one field or losing many of your fields altogether. 

My workaround for a while was to export, if a point file, the table to csv with x,y fields. For polygons, the process involved exporting a kmz, converting to kml with Google Earth, uploading to fusion, downloading csv, merging with attribute data in excel or back in ArcGIS and then uploading a csv. I’m sure that wasn’t the most efficient or only way to do it but at least now I know how painful it was to fully appreciate how nice it is to have a full-on shapefile to kml convertor.

So while watching Google’s Mano Marks talk about Fusion Tables in a video and then again in a video from Google’s I/O 2011: Managing and visualizing your geospatial data with Fusion Tables I heard about a tool called Shape Escape or ShpEscape. ShpEscape converts a zipped up shapefile into a Google Fusion table with Geometry column that allows you to overlay it over Google Maps like a kml.

I’ve been using Google Fusion for a few months now so I’m by no means an expert but if you have any questions feel free to hit me up at dms2203 at columbia dot edu

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.



Post-Election Maps

Like many of you, we have have been enjoying some of the latest election maps in the wake of last weeks election results.  We thought we would share a few, in case you haven’t seen them yet.

The New York Times once again has created a number of excellent post-election static and interactive maps, their election results maps allow you to investigate results to the county level, and to view the shift in party voting by county compared to the last four elections.

The Digital Scholarship lab at the University of Richmond has created “Voting America: United States Politics, 1840-2008” which contains a terrific collection of map animations and interactive mapping applications for every presidential election since 1840.

Mark Newman, a professor of physics at the University of Michigan, has converted the traditional red/blue maps into cartograms – distorting the areas of states and counties to reflect the relative population.

Want to create your own election maps?  EDS can help you get started with United States Presidential Election Results for recent elections in Datagate,  and various boundary files that can be downloaded through our Spatial Data Catalog.

Google Maps NYC Transit

For those of you have not seen it yet – this week Google has added New York city transit data to Google Maps, allowing route planning on public transit.

You can plan routes on NYC Transit, LIRR, the Metro-North, the Staten Island Ferry and Long Island Buses.  The interface is intuitive and admittedly pretty fast, but routing options don’t seem to be as robust as some other products (like Hopstop), particularly finding alternate routes.


Working on a map presentation and want your labels to show up in something other then Times New Roman or Arial?  TypeBrewer is a new online tool that can help you make choices regarding type fonts and labeling strategies for you map projects and presentations (The name is inspired from ColorBrewer – another online tool we have recommended in the past for helping choose color schemes for maps).  TypeBrewer is a Flash based browser application that allows you to choose from several pre-selected font families and displays them on a sample map, where you are able to interactively manipulate the font characteristics and appearance.   Once you generate a configuration that you like, TypeBrewer allows you to download the template specifications or export the simple map to the Adobe Illustrator format.

Water Watch

Eye on Earth Water Watch is a new interactive map viewer which is part of a five year partnership by The European Environmental Agency (EEA) and Microsoft. It includes more than 21,000 bathing sites across Europe, each site given a rating by both the EEA and by users.

The EEA water quality ratings come from the 1990 – 2007 coastal  and inland water quality analysis carried out by the European Commission.

It’s great to see the display of which years are included in the EEA rating when clicking on a site along side the number of user ratings, and a section for user comments.

Although I do like this site, it’s nice to see the datasets used are available for download so someone could potentially do other types of analysis. There’s also a data viewer and map viewer for looking at the data in a different way.

Meiji era Kantō region web map

Historical Agricultural Environment Search System (rough translation of 歴史的農業環境閲覧システム)

For those of you who are interested, there is a new web mapping service up showing seamless georeferenced maps of the Kantō region in Japan during the early to mid Meiji era. Overlayed on top of this are current road, river, and land use to view change. And as a added plus, a KMZ file is also available to view the full Meiji era maps in Google Earth,which ran a little slow when I tried it but was worth the wait.

Although the site is entirely in Japanese, it’s still easy enough to navigate around if you can’t read the characters.

Either choosing a location from the right hand side or just clicking on one of the places (marked by red circles) on the map opens up the mapping application – all the components are open source. If you overlay the 1997 land use data (it’s a little coarse compared to the 1880 data) you can see some of the changes.

The legend for the 1997 land use data on the map is in the FAQ – here’s a rough translation.

Left column – rice field (水田), other agriculture (その地農用地), forest (森林),  waste or unused land (荒地), built up area (建物用地)

Right column – transportation (幹線交通用地), other land (その地の用地), water bodies (河川および湖沼), beach (海浜), golf course (ゴルフ場)

If anyone has a better translation let me know and I’ll update the English categories.


onegeology The OneGeology Portal is relatively new and is the product of a 2007 accord calling for the creation of 1:1 million scale (or better) global, regional, and national geologic map data.

There are several participants and currently there are data for a handful of countries and regions but a fully operational version is scheduled for release in August 2008.

A nice feature is the ability to export to either a KML for Google Earth or a WMC which you can load back into OneGeology at a later time and will return you to the same scale as and remember which layers you loaded.

Ride the City

Looking for a safe route for a bike ride through New York City? Ride the City helps find the safest bike route between two points by either entering in address locations or by placing points on a map. Emphasis is places on use of bike lanes and greenways and excludes roads not meant for bikes at all.

The base data mostly comes from the NYC Dept. of City Planning DCPLION Street data, the base map comes from Google Maps, and OpenLayers is used for the markers, vector lines, and pop-ups. More info on what was used can be found in the Ride the City FAQ.