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Terraserver.com sat images

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BigInch

Petroleum
Jun 21, 2006
15,161
I've been looking at 15m/pix resolution photos. What kind of distortion is there at N 37º Lat? Can I find the m/degree latitude for 37-38 N and m/deg longitude and assume the photos are streached in the same proportion? That (I think) gives me 1:1.3 streatch factor. Could that be right?

BigInch[worm]-born in the trenches.
 
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no, the original terraserver looks like the googlemap. I was comparing to the wrong one. They both look the same.

Anyway. It appears the 1.25 stretch factor is correct, based on the horizontal, vertical and diagonal distances calculated between the map lat/long coordinates using the NOAA server that calculates dist between 2 pts of known lat & long.

BigInch[worm]-born in the trenches.
 
I compared the stretched version of the sat photo to the airport plan. They match within a degree or two.

Now the question is why does Terraserver.com sell distorted photos? Do they take up less space on their servers or something?

BigInch[worm]-born in the trenches.
 
Results,

malagaairportgeodeticfr6.jpg


BigInch[worm]-born in the trenches.
 
The distorted images may only be characteristic in some areas of the world. This image of Boston's Logan Airport was not transformed in any manner and the airport plan overlayed exactly.

bostonairportoverlayjc3.jpg


BigInch[worm]-born in the trenches.
 
This is getting worse.

I calculated the distances between the map corners myself, and I do not get the same distances using the usda calculator. All this could be the result of an error in the usda great circle calculator,


although that doesn't explain the apparently misaligned runway plan.

Can anybody suggest a known reliable distance calculator based on the W84 Geoid?

BigInch[worm]-born in the trenches.
 
That one is a great site!

pleanty of Excels to calculate distances bwtn lat & long.. lo to hi accuracy.

fixed error in my spreadsheet, so distortions are back in the sat photos, at 15 AND 30 m/pix resolutions

round and round...

BigInch[worm]-born in the trenches.
 
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