Pamshadedr...User Manual(1) General Commands Manual Pamshadedr...User Manual(1)
NAME
pamshadedrelief - generate shaded relief image from an elevation map
SYNOPSIS
pamshadedrelief
[-gamma g]
DESCRIPTION
This program is part of Netpbm(1).
pamshadedrelief creates a shaded relief image from an elevation map. A
shaded relief image is a visual image of terrain, showing the terrain as
if illuminated by oblique light and viewed from above, so that the
brightess of each spot depends upon its slope. A common example of a
shaded relief image is a relief map of the Earth, which shows mountains
and valleys.
The image pamshadedrelief creates is as if illumated by a light source
from the left.
The output image is a PAM with tuple type GRAYSCALE.
The program pamcrater is a good thing to use to demonstrate the function
of pamshadedrelief. It generates a terrain map of a cratered landscape.
$ pamcrater | pamshadedrelief | pamx
OPTIONS
In addition to the options common to all programs based on libnetpbm
(most notably -quiet, see ]8;;index.html#commonoptions\ Common Options]8;;\ ), pamshadedrelief recognizes
the following command line option:
-gamma factor
-g factor
The specified factor is used to gamma adjust the image in the
same manner as performed by pnmgamma. The default value is 1.0,
which results in a medium contrast image. Values larger than 1
lighten the image and reduce contrast, while values less than 1
darken the image, increasing contrast.
Note that this is separate from the gamma correction that is part
of the definition of the PAM GRAYSCALE format. The image
pamshadedrelief generates is a genuine, gamma-corrected PAM
GRAYSCALE image in any case. This option simply changes the con-
trast and may compensate for a display device that does not cor-
rectly render PAM GRAYSCALE images.
DESIGN NOTES
The-gamma option isn't really necessary since you can achieve the same
effect by piping the output from pamshadedrelief through pnmgamma. How-
ever, pamshadedrelief performs an internal gamma map anyway in the
process of rendering the elevation array into the PAM GRAYSCALE format,
so there's no additional overhead in allowing an additional gamma ad-
justment.
SEE ALSO
ppmrelief(1) pnmgamma(1), pnmsmooth(1) pamcrater(1) pam(1),
AUTHOR
pgmcrater, from which this is derived, was written by John Walker:
John Walker
Autodesk SA
Avenue des Champs-Montants 14b
CH-2074 MARIN
Suisse/Schweiz/Svizzera/Svizra/Switzerland
Usenet:kelvin@Autodesk.com
Fax:038/33 88 15
Voice:038/33 76 33
Permission to use, copy, modify, and distribute this software and its
documentation for any purpose and without fee is hereby granted, without
any conditions or restrictions. This software is provided "as is" with-
out express or implied warranty.
HISTORY
pgmcrater was split into pamshadedrelief and pamcrater in Netpbm 10.68
(September 2014). See the history section of the pamcrater manual for
details.
DOCUMENT SOURCE
This manual page was generated by the Netpbm tool 'makeman' from HTML
source. The master documentation is at
http://netpbm.sourceforge.net/doc/pamshadedrelief.html
netpbm documentation 26 July 2014 Pamshadedr...User Manual(1)
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