[Proj] Algorithms & Plate Carrée

Irwin Scollar al001 at uni-koeln.de
Mon Jul 23 08:58:33 EST 2012

Noel Zinn wrote:

"Your question can be interpreted in many ways 
and it's not clear to me what you really mean. "

I didn't express myself clearly.  Sorry.

For example, given a 1 kilometer square area in 
Google Earth, and the same 1 kilometer square 
area on a precision digital map made with ground 
or aerial survey in UTM-WGS84, there will be an 
error when measuring coordinates in GoogleEarth 
imagery compared with those on the map for 
visible features in both. This error which will 
vary over the area because the projections are 
not identical in addition to the absolute error 
at a given known point as cited by Noel, plus the 
optical and atmospheric distortion errors in the GE imagery.

Assuming that one or more points in the Google 
Earth image have known coordinates in UTM 
obtained either from maps as above or with 
differential ground GPS measurement from known 
points nearby,  and that optical, perspective and 
atmospheric distortions can be neglected (?), how 
can one correct for the distortion due to Plate Carrée?

Might this be the same as calculating something 
like an inverse of a Tissot Indicatrix for the small area?


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