The structure of a city via Twitter

From Mashable Tech.

Check out this gorgeous visualization of NY City's tweetopolis from Oakland-based programmer Eric Fischer.

He plots out the motion of New Yorkers using public tweets on Twitter with geotags from May 2011 until January.

The project lays out around 10,000 geotagged tweets and 30,000 point-to-point trips in cities like New York City to plot the flow of people in terms of favored paths. In his map of NYC, seen above, there is a huge ink blot lining Broadway; as we’ve long suspected, it looks like the busy avenue is the backbone of the city.

Using a base map from OpenStreetMap, he drew out transit paths using Tweets. Movements are indicated on the geolocation of a Tweet, with an individual’s start point marked with one geotagged Tweet and ending with the next geotagged Tweet. This is what creates a mass of traffic routes.

Similar viz of the east bay“If you just draw lines from the beginning to the ending of each trip, you get a big mess, so the challenge is to come up with more plausible routes in between,” Fischer told Mashable. “That is where the 10,000 individual geotags come in, the most plausible routes are ones that pass closely through places that other people have been known to go.”

Fischer used Dijkstra’s Algorithm to calculate what exactly to map out. For those of who haven’t thought about math since high school algebra, that’s an equation that maps out the shortest path between two points on a graph. For this project, the equation pointed to the relevant paths to map out a city’s most dense corridors.

This might be of use for our mobility project with our space.

More here.

Artisan basemap sandwich - a great name for a band, and a new basemap from ESRI

An example from southern caliEver admired those lovely muted gray maps from NYTimes and elsewhere that are in vogue now? Subtle, calming, with great figure to ground contrast? Canvases on which your data can pop? I know I have. Now ESRI cartographers add these options to their basemap collection. Read more about it in these posts:

Esri Canvas Maps Part I: Author Beautiful Web Maps With Our New Artisan Basemap Sandwich, and Esri Canvas Maps Part II: Using the Light Gray Canvas Map effectively.

From Greeninfo Network.

To map or not to map

A recent post by Matt Ericson from the New York Times on the importance of knowing when to map geographic data and when not to. He states that we are sometimes too quick to map geographic data. In some cases a chart or table can better represent geographic information and tell a more effective story. In some cases there are no better alternatives than to map geographic data. The important thing is to remember that there are multiple avenues of presenting geographic data in which a map may or may not always be the best form to convey data and ideas. In the post he also provides examples of some cases he has run in to where a map and where a table has provided a more effective means of geographic data presentation.

See the full post here.

India-Pakistan border as seen from space

From NASA re-posted via Bostom.com's The Big Picture photojournalist website comes this fascinating, geographically-pertinent image: "The India-Pakistan border appears as an orange line in this photograph taken by the Expedition 28 crew on the International Space Station on August 21, 2011. The fence between the two countries is floodlit for surveillance purposes. Srinagar (left), Islamabad (bottom center), Lahore (center near the border line) and Delhi (top center) can be seen as brighter spots. (NASA/Handout/Reuters)#"

Interactive map of Irene: NYTimes

Here is the NYTimes live map showing Irene's progress.

Looks like it went directly over Beaufort and the NOAA Marine Lab. Hope everyone is ok.

Irene as of 8:30 PST

The NYTimes site also has some great tools showing current wind speed.

Sacramento - vulnerable to levee breaks

Sacramento's levee system: levees are in orange, the inset is the capital under floodwaters.A good article from NYTimes discussing the vulnerability of Sacramento to levee breaks. Scientists consider Sacramento — which sits at the confluence of the Sacramento and American Rivers and near the delta — the most flood-prone city in the nation. The city is at risk from earthquake-damaged levees and storm related flooding.

London Mapping Festival: 18 months of all things maps + london. Sign me up.

The London Mapping Festival 2011 – 2012, or LMF for short, is an exciting and unique initiative being launched in June 2011 and will run through to December 2012. It sets out to promote greater awareness and understanding of how maps and digital geographic data are being created and used within the Capital.   Through a diverse range of activities LMF will engage with a wide audience of mapping enthusiasts whether they are professionals, enthusiasts or others. We should do something like this for the SF Bay Area. More here.

The City Project: Park Poor, Income Poor, and People of Color

example from orange countyThe City Project has released a report for California analyzing access to green space.  The report uses geographic, demographic, economic and historical data to map and analyze access to the region's green space. In addition, the report examines access to green space based on income, race or ethnicity.
The report's GIS maps were produced by GreenInfo Network and help illustrate unfair disparities in park access.

The areas that are symbolized with red and crosshatching indicate areas that are park poor (less than 3 acres of parks per 1,000 residents) and income poor (below $47,331 median household income), and disproportionately populated by people of color.

the world according to facebook

From the BBC: Using some of the information on friends data from facebook's 500m members, intern Paul Butler has constructed an interesting map of the world's connections. The map above is the result of his attempts to visualise where people live relative to their Facebook friends. Each line connects cities with pairs of friends. The brighter the line, the more friends between those cities.

21st century maps are commercial products, not national efforts

From the Map Room. Popsci has an interesting article about "how digital maps are changing the landscape of the 21st century". Among the interesting bits is this RAD image, showing a moving plane captured by the GeoEye satellite. But the main argument is that mapping used to be the purview of nations and international bodies, but now commercial entities like Google, Bing, Mapquest, and other digital services are the principal mapmakers of the 21st century. Now, maps are commercial products, compiled from a variety of sources that often blend government-derived mapping data with user-generated content. The article suggests they are subject to conflicting information, differences of political opinion and outright error. In addition, the article claims we haven't really focused on this transfer of cartographic power, but of course many have commented on this (e.g. Goodchild's VGI article frfom 2007 in Geojournal) in the academic world.