[GRASS-user] r.univar: different results with different projections?

[Carlos Grohmann]

Hi all.

I'm analyzing some global-scale DEMs, like ETOPO1/2, SRTM30_PLUS, etc.

I'm getting the statistics for the whole dataset with r.univar, but today I
noticed that the results differ if I use different projections. (GRASS 7.1)

For example, ETOPO2:

Using a latlong pseudo-projection (plate carré)


min: -10791
max: 8440
mean: -1888.6480792
median: -2457
stddev: 2650.01922839
p25: -4273
p75: 216


And using equal-area cylindrical:

min: -10791
max: 8440
mean: -2379.78247747
median: -3291
stddev: 2507.89668617
p25: -4541
p75: 94



Are these differences expected? I would think that they should be the same,
regardless of projection (I'm thinking on the elevation values as an array
of values).

thanks

Carlos





-- 
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.
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