I was updating the r.colors docs, as the given rules in the html are out of sync with the program.
I'm not sure how to describe some of the canned rules, particularly curvature and evi.
Anyone know what these color tables were intended to map?
Thanks,
~ Eric.
On Jan 24, 2008, at 3:57 PM, Patton, Eric wrote:
I was updating the r.colors docs, as the given rules in the html are out of sync with the program.
I'm not sure how to describe some of the canned rules, particularly curvature and evi.Anyone know what these color tables were intended to map?
curvature is for terrain curvatures (based on the color table that you get for curvatures
from v.surf.rst and r.slope.aspect), something like this
http://skagit.meas.ncsu.edu/~helena/wrriwork/lakewh/honpc.jpg
http://www.grassbook.org/gallery/chapters/s060806f010_pcurv.jpg
http://www.grassbook.org/gallery/chapters/s0609f020_topoanal.jpg
negative values are blues, positive values are yellow to red (I will double check that to make sure).
Generally it is useful for maps that have both positive
and negative values.
I don't know about evi,
Helena
Thanks,
~ Eric.
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--- Helena Mitasova <hmitaso@unity.ncsu.edu> wrote:
Eric Patton wrote:
> I was updating the r.colors docs, as the given rules in the html
> are out of sync with the program.
> I'm not sure how to describe some of the canned rules, particularly
> curvature and evi.
>
> Anyone know what these color tables were intended to map?
Helena:
curvature is for terrain curvatures (based on the color table that
you get for curvatures
from v.surf.rst and r.slope.aspect), something like this
http://skagit.meas.ncsu.edu/~helena/wrriwork/lakewh/honpc.jpg
http://www.grassbook.org/gallery/chapters/s060806f010_pcurv.jpg
http://www.grassbook.org/gallery/chapters/s0609f020_topoanal.jpgnegative values are blues, positive values are yellow to red (I will
double check that to make sure).
Generally it is useful for maps that have both positive
and negative values.
see also r.colors.stddev from the wiki addons page. To me it is a very
interesting module for setting color tables for difference maps etc.
I don't know about evi,
It is enhanced vegetation index from eg MODIS data like NDVI.
see http://earthobservatory.nasa.gov/Library/MeasuringVegetation/
Hamish
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On Jan 25, 2008 12:08 AM, Hamish <hamish_b@yahoo.com> wrote:
> Eric Patton wrote:
> > I was updating the r.colors docs, as the given rules in the html
> > are out of sync with the program.
> > I'm not sure how to describe some of the canned rules, particularly
> > curvature and evi.
...
It is enhanced vegetation index from eg MODIS data like NDVI.
see http://earthobservatory.nasa.gov/Library/MeasuringVegetation/
EVI (enhanced vegetation index) is used to monitor vegetation.
EVI was developed with improved sensitivity in areas of dense,
green vegetation with large amounts of chlorophyll (where NDVI tends
to saturate). Additionally, it is less sensitive to haze and atmospheric
effects since the blue channel is included in the denominator. It also
minimizes the influence of background interference caused by bare
soil reflecting off the ground.
chees
Markus
Helena:
curvature is for terrain curvatures (based on the color table that
you get for curvatures
from v.surf.rst and r.slope.aspect), something like this
http://skagit.meas.ncsu.edu/~helena/wrriwork/lakewh/honpc.jpg
http://www.grassbook.org/gallery/chapters/s060806f010_pcurv.jpg
http://www.grassbook.org/gallery/chapters/s0609f020_topoanal.jpgnegative values are blues, positive values are yellow to red (I will
double check that to make sure).
Generally it is useful for maps that have both positive
and negative values.
Hamish:
see also r.colors.stddev from the wiki addons page. To me it is a very
interesting module for setting color tables for difference maps etc.
Neat, I'll have to check this one out.
Helena:
I don't know about evi,
Hamish:
It is enhanced vegetation index from eg MODIS data like NDVI.
see http://earthobservatory.nasa.gov/Library/MeasuringVegetation/
Thanks to all for the info; I've updated the color rules list and added some descriptions.
I've been having trouble with svn today (see my other thread from today), but the commit
seems to have made it through on Trac.
~ Eric.
