Manual: pamshadedrelief

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 ter‐
       rain,  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	  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 de‐
	      fault value is 1.0, which results in a medium contrast image.  Values larger than 1 lighten the image and	 re‐
	      duce 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 for‐
	      mat.  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 pamshade‐
       drelief through pnmgamma.  However, 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
       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@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	 im‐
       plied 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)