[Talk-us] identifying TIGER deserts

Ian Villeda villeda at mapbox.com
Thu Dec 20 16:12:12 GMT 2012


Hello all, 

Ruben led out MapBox's analysis, the results of which you can see in his previous message. While these maps do a fairly good job of identifying areas that have and have not been edited, we're not entirely satisfied with their ability to identify where TIGER ways just don't represent the actual geographic location of roads on the ground. 

Another thought we've had is to do some flavor of comparative analysis between 2007 TIGER and 2012 TIGER. This might me clipping  2007 to the 2012 dataset to identify where roads do not overlap (and then perhaps some raster/binning to identify problem areas). Just wondering what other ideas might be out there - hit me up with your ideas. 

thanks! 

-- 
ian villeda
mapbox | developmentseed
https://twitter.com/ian_villeda


On Wednesday, December 19, 2012 at 8:39 PM, Ruben Lopez Mendoza wrote:

> 
> We've worked out some kinks of our first attempt to identify TIGER deserts, and produced maps a couple maps along the way.
> 
> 
> Average version of all highway =* ways https://tiles.mapbox.com/ruben/map/map-badetj1b#7.00/37.927/-78.466
> 
> 
> Percent version 1, highwahy=* ways per gridcell http://tiles.mapbox.com/ruben/map/map-4t3notfw#9.00/37.2805/-78.2528
> 
> 
> Comparison: http://bl.ocks.org/d/ff2607349777ddee9181/
> 
> 
> As input we used a database of all highway=* ways and their version number created using Osmosis and a grid generated from a Natural Earth shapefile.
> 
> 
> I created a postgres function that populates a new table called tiger_grid. For each cell, we calculated each of the following:
> 
> amount_version1
> amount version2
> percentage _version1
> percentage version2
> average_version
> 
> 
> I've captured all of this work - the postgres functions, shapefiles, and tilemill projects in the a repo here:https://github.com/Rub21/tiger-deserts
> 
> next steps
> 
> A few obvious steps stand out, including rendering a national version of these maps. I'd also love to figure out whether it makes sense to join forces with Mike Migurski's Green Means Go map.
> 
> 
> It'd also be interesting to use a smarter Osmosis command (and the full history file) to limit the input data to just those ways created by the 3 primary user accounts associated with the TIGER import:https://github.com/MapQuest/TIGER-Edited-map/blob/master/inc/layer-tiger.xml.inc#L45 (h/t Migurski)
> 
> 
> 
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