gdaldem
analyzes and visualizes terrain elevation
TLDR
Generate a hillshade from a DEM
$ gdaldem hillshade [dem.tif] [hillshade.tif]
Create a slope map in degrees$ gdaldem slope [dem.tif] [slope.tif]
Generate an aspect map$ gdaldem aspect [dem.tif] [aspect.tif]
Create color relief using a color table file$ gdaldem color-relief [dem.tif] [colors.txt] [relief.tif]
Generate hillshade with custom light direction and altitude$ gdaldem hillshade -az [315] -alt [45] [dem.tif] [hillshade.tif]
Compute Terrain Ruggedness Index$ gdaldem TRI [dem.tif] [tri.tif]
SYNOPSIS
gdaldem mode [options] input output
DESCRIPTION
gdaldem analyzes and visualizes digital elevation models. It generates terrain derivatives including hillshade, slope, aspect, and various roughness indices.The tool produces visualization-ready output from raw elevation data. Hillshading creates realistic terrain lighting. Slope and aspect support terrain analysis.gdaldem is essential for cartographic terrain representation and geomorphological analysis.
PARAMETERS
MODE
Operation: hillshade, slope, aspect, color-relief, TRI, TPI, roughness.INPUT
Input DEM raster.OUTPUT
Output raster file.-az DEGREES
Light azimuth for hillshade.-alt DEGREES
Light altitude for hillshade.-s SCALE
Ratio of vertical to horizontal units (e.g., 111120 for feet with degree coordinates).-z FACTOR
Vertical exaggeration factor.-of FORMAT
Output raster format (default: GTiff).-compute_edges
Compute values at raster edges and nodata boundaries.--help
Display help information.
INSTALL
sudo apt install gdal-bin
sudo apk add gdal-tools
CAVEATS
Requires properly scaled DEM. Edge effects at boundaries. Large files need more memory.
HISTORY
gdaldem is part of GDAL (Geospatial Data Abstraction Library), providing DEM analysis tools for terrain visualization and analysis.
SEE ALSO
gdal_contour(1), gdalinfo(1), ogr2ogr(1)
