man > pamshadedrelief(1)

Pamshadedrelief User Manual(1)         General Commands Manual        Pamshadedrelief 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 exam‐
       ple 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  Common Options ), 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  contrast
              and  may  compensate for a display device that does not correctly 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.  However, pamshadedrelief performs an internal
       gamma map anyway in the process of rendering the elevation array into the PAM GRAYSCALE  for‐
       mat, so there's no additional overhead in allowing an additional gamma adjustment.



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 AT 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" without 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              Pamshadedrelief User Manual(1)