Opened 11 years ago

Last modified 3 years ago

#83 assigned defect

r.param.scale - plan curvature doesn't work

Reported by: guano Owned by: guano
Priority: major Milestone: 6.4.6
Component: Raster Version: svn-trunk
Keywords: r.param.scale Cc: grass-dev@…
CPU: Unspecified Platform: Unspecified

Description

Maps of plan curvature calculated using r.param.scale results in a map with a very very very narrow distribution (histogram attached), therefore we can't see any of the features.

Attachments (2)

planc_histo.png (4.6 KB) - added by guano 11 years ago.
histogram of plan curvature
planc_histogram_equalised.png (52.6 KB) - added by guano 11 years ago.
map of plan curvature. colortable rainbow, histogram equalised

Download all attachments as: .zip

Change History (11)

Changed 11 years ago by guano

Attachment: planc_histo.png added

histogram of plan curvature

Changed 11 years ago by guano

map of plan curvature. colortable rainbow, histogram equalised

comment:1 Changed 11 years ago by guano

Keywords: r.param.scale added
Milestone: 6.4.06.3.0
Owner: changed from grass-dev@… to guano
Status: newassigned
Version: unspecifiedsvn-trunk

comment:2 Changed 11 years ago by martinl

Cc: grass-dev@… added

comment:3 Changed 11 years ago by neteler

Milestone: 6.3.06.4.0

comment:4 Changed 11 years ago by neteler

# Spearfish

g.region rast=elevation.10m -p
r.param.scale elevation.10m out=planc param=planc
r.univar planc
total null and non-null cells: 2654802
total null cells: 0

Of the non-null cells:
----------------------
n: 2654802
minimum: -56.0318
maximum: 63.5533
range: 119.585
mean: 0.000136618
mean of absolute values: 0.0203089
standard deviation: 0.0846529
variance: 0.00716612
variation coefficient: 61963.3 %
sum: 362.6935644354

looks like equally distributed to me. The question is: is the color coding bad or is the result wrong? This could be tested with synthetic curves (see source:grass/trunk/testsuite/raster/rhemisphere.sh)

Markus

comment:5 Changed 10 years ago by hamish

CPU: Unspecified
Platform: Unspecified

adding skewness and kurtosis to r.univar would help in diagnosing this bug. see http://article.gmane.org/gmane.comp.gis.grass.devel/31686/

comment:6 Changed 6 years ago by helena

I just tried it out - it is just bad color coding - changing to curvature color table works. This can be either fixed in the code or just suggest in the manual to set the color table to curvature. I think this can be closed.

comment:7 Changed 6 years ago by hamish

Component: DefaultRaster
Milestone: 6.4.06.4.4

comment:8 in reply to:  6 Changed 6 years ago by neteler

Replying to helena:

I just tried it out - it is just bad color coding - changing to curvature color table works. This can be either fixed in the code

Curvature color code may be taken from here:

http://trac.osgeo.org/grass/browser/grass/branches/releasebranch_6_4/raster/r.slope.aspect/main.c#L1177

comment:9 Changed 3 years ago by neteler

Milestone: 6.4.46.4.6
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