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List:       grass-user
Subject:    [GRASS-user] about area results from r.stats
From:       Carlos Grohmann <carlos.grohmann () gmail ! com>
Date:       2014-06-14 18:19:48
Message-ID: CALkQ4RCyLXJ27oMuQhD6orTkro7N6N5GtM0-cxdvKHO6=vMnng () mail ! gmail ! com
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Hi there

I'm doing a comparative analysis of Global DEMs, and I using the results
from r.stats, combined with python/matplotlib to make some histograms.
According to r.stats manual, the area results are reported as square
meters, but my values seem a bit off. Attached is a histogram of ETOPO1,
with 50m bins. The mode of the oceanic area goes to 6.000.000 m2, and the
coastal plains reach 1.3 E7 m2.

But looking to the histogram made by Eakins and Sharman (
http://www.ngdc.noaa.gov/mgg/global/etopo1_surface_histogram.html), the
values don't quite match. Their histogram show a mode with about 350 km2
for the oceans and one with 750 km2 at the coastal areas.

any hints on this? From what I could find, r.stats does account for cell
area variation.

best

Carlos










 [image: Inline image 1]

-- 
Prof. Carlos Henrique Grohmann
Institute of Energy and Environment - Univ. of São Paulo, Brazil
- Digital Terrain Analysis | GIS | Remote Sensing -

http://carlosgrohmann.com
http://orcid.org/0000-0001-5073-5572
________________
Can't stop the signal.

[Attachment #7 (text/html)]

<div dir="ltr">Hi there<div><br></div><div>I&#39;m doing a comparative analysis of \
Global DEMs, and I using the results from r.stats, combined with python/matplotlib to \
make some histograms. According to r.stats manual, the area results are reported as \
square meters, but my values seem a bit off. Attached is a histogram of ETOPO1, with \
50m bins. The mode of the oceanic area goes to 6.000.000 m2, and the coastal plains \
reach 1.3 E7 m2.</div>

<div><br></div><div>But looking to the histogram made by&nbsp;Eakins and Sharman (<a \
href="http://www.ngdc.noaa.gov/mgg/global/etopo1_surface_histogram.html">http://www.ngdc.noaa.gov/mgg/global/etopo1_surface_histogram.html</a>), \
the values don&#39;t quite match. Their histogram show a mode with about 350 km2 for \
the oceans and one with 750 km2 at the coastal areas.</div>

<div><br></div><div>any hints on this? From what I could find, r.stats does account \
for cell area variation.</div><div><br></div><div>best</div><div><br></div><div>Carlos</div><div><br></div><div><br></div><div><br></div>


<div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div>&nbsp;<img \
src="cid:ii_1469b9745b493946" alt="Inline image 1" width="454" \
height="319.01486620416256"><br clear="all">

<div><br></div>-- <br><div dir="ltr">Prof. Carlos Henrique Grohmann<br>Institute of \
Energy and Environment - Univ. of São Paulo, Brazil<div>- Digital Terrain Analysis | \
GIS | Remote Sensing -&nbsp;</div><div><br></div><div><a \
href="http://carlosgrohmann.com/" target="_blank">http://carlosgrohmann.com</a></div>

<div><a href="http://orcid.org/0000-0001-5073-5572" \
style="font-size:13px;color:rgb(17,85,204);font-family:arial,sans-serif;background-color:rgb(255,255,255)" \
target="_blank">http://orcid.org/0000-0001-5073-5572</a><br><div>

________________<br>Can&rsquo;t stop the signal.</div></div></div>
</div></div>

--f46d04428cbaa677be04fbcfd857--


["etopo1.png" (image/png)]

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