[Talk-us] identifying TIGER deserts

Alex Barth alex at mapbox.com
Fri Dec 7 21:09:40 GMT 2012


Mike -

AWESOME looking map and similar to what Ian and Ruben are working on. Would you be open to share how you built that map? How hard (time consuming) is it to regenerate?

I'd love to get a regularly updated map out there showing TIGER deserts. We'd use that ourselves to start fixing some of the worst areas in terms of geographic accuracy. But obviously such a map would be a good thing to have for the wider community.

On Dec 7, 2012, at 1:32 PM, Michal Migurski <mike at teczno.com> wrote:

> That's great!
> 
> I've been thinking about some of the same things, inspired by Dennis Zielstra's talk at SOTM-US. I'm looking at road lengths for 1x1 kilometer squares, measuring OSM user count (post-import) vs. possibility for improvement between 2007 and 2012 TIGER/Line data:
> 
> 	http://mike.teczno.com/img/osm-users-imports-2012-09.png
> 	- Blue means 2012 data would be an improvement
> 	- Red/Yellow means there are active OSM users there
> 
> I used an Albers equal-area projection to ensure correct length and density regardless of latitude, and my intent for this is to produce county-by-county views that GIS managers in different jurisdictions can use to understand whether their data is worth important, and what OSM users they'd need to contact in order to be successful.
> 
> I have a slippy map version of this but the projection registration is off by a few hundred meters; need to figure out why that is and fix it.
> 
> -mike.
> 
> On Dec 7, 2012, at 10:00 AM, Ian Villeda wrote:
> 
>> 
>> Hey team, 
>> 
>> Over here at MapBox we were inspired by Martjin's great post on identifying TIGER deserts[1], so we're attempting to effectively identify TIGER deserts for the rest of the continental U.S. (sorry Hawaii + Alaska, you're next). The goal is to create a slippy map from zoom level 2 to 15(?) such that it's easy to find the places in need of the most love.
>> 
>> We have a osmium-genereated postigs database with all ways tagged as highway=* and their version number. The plan to run the analysis against a 5x5 km grid, although we will probably play with the size of the gridcell. Another option might be to conduct the analysis and varying levels of granularity. 
>> 
>> We're still consiering different methods of analysis - the goal being to normalize way density to display better identify TIGER deserts. We'd would love your thoughts / input / reactions. A few ideas we've tossed around / are activley pursuing:
>> 
>> - percent of version 1 and/or 2 ways in each gridcell
>> - average number of version 1/2 ways per gridcell
>> - using a threshold value(s) similiar to Martjin's approach
>> - [your ideas here]
>> 
>> Ultimately we'd like showcase the rendered results in site that would make editing TIGER deserts easy. For now though this is just a heads up and an invitation if you have any thoughts on how better to identify TIGER deserts. 
>> 
>> thanks! 
>> 
>> [1]: http://oegeo.wordpress.com/2012/10/21/binders-full-of-tiger-deserts/
>> -- 
>> ian villeda
>> mapbox | developmentseed
>> https://twitter.com/ian_villeda
>> 
>> 
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> 
> ----------------------------------------------------------------
> michal migurski- contact info and pgp key:
> sf/ca            http://mike.teczno.com/contact.html
> 
> 
> 
> 
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Alex Barth
http://twitter.com/lxbarth
tel (+1) 202 250 3633







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