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

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.

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.