Hill Shading - An Effective Visualization Technique for Digital Elevation Models (DEM)

Have you ever looked at a map or terrain model and noticed how some areas appear lighter while others seem darker?

This effect, known as hill shading or shaded relief, is a common visualization technique used to represent the three-dimensional nature of digital elevation models (DEMs) on two-dimensional surfaces like maps or computer screens.

The calculation of hill shading values is based on basic principles of lighting and surface orientation. By digitally positioning a "sun" at a specified azimuth and altitude angle, the illumination of each cell within a DEM can be mathematically modeled. The results are realistic, high-contrast hillshade maps that effectively convey the three-dimensional nature hidden within two-dimensional elevation models.

Hill shading works by simulating the shading of landscapes from a hypothetical light source. Areas that face the light source appear brighter, while surfaces that face away appear darker. This helps emphasize the relative heights, slopes, and orientation of terrain features.

When applied to DEMs generated from remote sensing data like LiDAR, hill shading is able to dramatically enhance the perception of landforms and terrain characteristics. Features like mountains, valleys, ridges and slopes are accentuated, allowing for easier identification and analysis. Hill shading is a valuable tool for mapmakers because it allows them to create more realistic and informative maps. Hill shading has become an integral part of geospatial data visualization and is widely used across industries like geomatics, geology, civil engineering, urban planning and more.

Effective visualization is so important for understanding spatial datasets.

Have you used hill shading in your work? I'd love to hear how it has helped with terrain analysis, map making or other geospatial applications.