pamshadedrelief

generate shaded relief image from a PAM height map

TLDR

Create shaded relief from a height map

$ pamshadedrelief [heightmap.pam] > [relief.pam]

Apply gamma correction to the rendered relief

$ pamshadedrelief -gamma [2.0] [heightmap.pam] > [relief.pam]

Pipe to pamtopnm to view as PPM

$ pamshadedrelief [heightmap.pam] | pamtopnm > [relief.ppm]

Render and encode as PNG

$ pamshadedrelief [heightmap.pam] | pnmtopng > [relief.png]

SYNOPSIS

pamshadedrelief [-gamma value] [pamfile]

pamshadedrelief reads a Netpbm PAM file containing a grayscale height map and produces a PAM image rendered as a shaded relief, simulating illumination of a 3D terrain by a virtual light source. Each output pixel encodes the brightness derived from the local slope of the height field, giving a hill-shading effect similar to topographic maps.The input must be a one-channel (grayscale) PAM image; sample values are interpreted as elevations. The illumination angle is fixed by the program. Output samples are gamma-corrected with -gamma so the contrast of the relief can be tuned without re-rendering the source data.

PARAMETERS

PAMFILE

Input grayscale PAM height map. If omitted, read from standard input.

-gamma VALUE

Apply gamma correction to the output. Values greater than 1 increase contrast in dark areas; values less than 1 reduce it. Default is 1.0.

INSTALL

sudo apt install netpbm

sudo dnf install netpbm

sudo pacman -S netpbm

sudo apk add netpbm

sudo zypper install netpbm

brew install netpbm

nix profile install nixpkgs#netpbm

CAVEATS

Part of Netpbm. The input must be a single-plane (grayscale) PAM image; PGM inputs should be promoted to PAM first. The light direction is hard-coded and cannot be changed from the command line. Output is a PAM image; convert to PPM or PNG for display with pamtopnm or pnmtopng.

HISTORY

pamshadedrelief was added to Netpbm to support cartographic and terrain visualization tasks. Netpbm provides a long-lived family of small, composable image utilities operating on the PNM/PAM family of formats.