[OSM-talk] Does Google use automated tracing from satellite imagery ?

[Jean-Marc Liotier]

I find the Yahoo satellite imagery useful for tracing in JOSM with 
wmsplugin, but when I just want to gaze at stunning sights of Earth's 
surface I go to Google, the quality of whose imagery never ceases to 
amaze me. I have noticed that in many places, in countries in which 
Google does not have significant commercial interest, even many villages 
have part of their street grid mapped. But looking a little closer, this 
is a partial mapping of a seemingly random subset of the grid, and none 
of those streets have names. Example in Takoradi, Ghana : 
http://j.mp/7Ay7wZ. This looks like what some grid recognition automaton 
would produce if configured to only trace the streets it detects with a 
certainty above a certain threshold. The result is imperfect, but it 
looks like a nice way to kickstart manual mapping of an area with the 
techniques we currently use.

So is anyone aware of automated tracing techniques that Google might be 
using ? Is automated tracing from legally available imagery something 
that the Openstreetmap project should study ? Street grid detection and 
automated tracing would make a nice JOSM plugin wouldn't it ?

Lakewalker does it for waterlines 
(http://wiki.openstreetmap.org/wiki/JOSM/Plugins/Lakewalker) and 
coastline tracing of Landsat imagery using other tools has been 
experimented with 
(http://www.mail-archive.com/talk@openstreetmap.org/msg12661.html). 
Other people have been playing with Potrace and Autotrace 
(http://wikitravel.org/en/Wikitravel_talk:How_to_draw_a_map#Automated_tracing_potrace_vs._autotrace) 
But I have found no mention of street tracing automation yet.