[Proj] Google Earth Accuracy

Ethan Alpert ealpert at digitalglobe.com
Sun Nov 30 11:08:40 EST 2008

I guess that's my point unless you are testing against a set of imagery
which you know is Aerial imagery orthorectified with a *very* fine DEM
or an areas with constant elevation. You can't make claims that the
presentation of the image is adversely affecting accuracy. 


For instance the DigitalGlobe Quickbird satellite is rated as 23m CE90
RMSE 14m.






From: proj-bounces at lists.maptools.org
[mailto:proj-bounces at lists.maptools.org] On Behalf Of Thomas Knudsen
Sent: Sunday, November 30, 2008 8:08 AM
To: PROJ.4 and general Projections Discussions
Subject: Re: [Proj] Google Earth Accuracy


2008/11/30 Ethan Alpert <ealpert at digitalglobe.com>

	How come no ones questioning the accuracy of the sensors that
	the imagery in Google Maps? I happen to know that satellite
imagery is
	not very accurate unless you have decent ground control and a
DEM. Even
	then it's not that great. It seems pointless to try to determine
	accuracy in Google Maps unless you understand where the imagery
	from and how it was produced.

At least where I live (Copenhagen, Denmark), the high resolution
layers of Google Maps come from very high precision
photogrametrically derived orthophotos, which should certainly
have an accuracy way better than the "few meters with occational
ten meter blunders" quoted earlier in this thread. 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.maptools.org/pipermail/proj/attachments/20081130/50703be9/attachment.html

More information about the Proj mailing list