☛ Crowdflow.net: “Fireflies HD” (iPhone fireflies 3) by Michael Kreil, July 12, 2011

Crowdflow is an experiment in crowdsourced geodata visualization initiated by Michael Kreil, Lorenz Matzat and others. It makes use of position data voluntarily handed by iPhone users to visualize Wi-Fi hot hotspots, cell phone coverage and users movement¹.
The above video shows the visualization of anonymized location data voluntarily provided by 881 iPhone users. The bright lights indicates actual location data provided by an active iPhone. The faded lights indicate an estimated location (while de iPhone is not actually providing data about it’s location: because it’s turned off, for example).
Michael Kreil gave an interesting (and only one?) interview to Deutsche Well. I particularly like what he has to say about the heuristic nature of data visualization:

It sounds like you don’t even know where this data visualization project is going. Is that how a lot of data visualization projects go, that you learn something through the process?
When you combine a lot of data, you never know what kind of information is in data. Maybe you have one data set, which has a lot of information [but you don’t know what it is], and you have a second data, also with no information, but at that point where you combine them, you can see what kind of information and correlations are there. That’s the scientific part. The journalistic part is to combine and look and see if there is any knowledge or information there.
You can’t say that ‘we want to prove that the mobile coverage is bad,’ or that ‘Apple is tracking us.’ You can’t prove that because you don’t know what’s in there. You have to collect it, dig through it, and then you can see what’s there.
So, in other words the story emerges from the data, and not the other way around?
Yep, definitely.

To read the whole interview, see “German data visualization specialists seek iPhone tracking data” by Cyrus Farivar and Sarah Steffen, May 9, 2011.
For more see Michael Kreil official website (German only) and his Google+ profile. He previously worked with German Green party politician Malte Spitz, analyzing data location retrieved from the politician personal cellphone. A little bit over one year ago the story made the headlines and raised questions about privacy. See Malte Spitz website, “Tracking Malte Spitz” on YouTube and “It’s Tracking Your Every Move and You May Not Even Know” (by Noam Cohen, The New York Times, March 26, 2011).
¹ Apple’s iPhones don’t have built-in GPS. They use Wi-Fi triangulation to estimates the iPhone position from the known locations of nearby cell networks. For a more complete explanation, see Michael Kreil: Deeper insights into Apple’s “GPS”