Relief Shading

Home

Techniques

Design Rules

Software

Analytical

Colors

Examples

Cartographers

History

Literature

Try It!

Links

Contact

Last update:
15/11/2006

LOCAL ADJUSTMENTS

The cartographer has to selectively adjust light direction and brightness of important landforms when producing shaded relief. For shading derived from a DEM, necessary local adjustments are achievable by two different methods:

Photoshop allows for the selective correction of gray values or to combine multiple shaded relief images created with differing illumination direction. This is a rather tedious, but currently the only viable method.

An alternative is the use of software specificially developed for cartographic relief shading.

A Concept for Local Adjustments

At the Institute of Cartography (ETH Zurich), development of an interactive relief shading application is underway. Still at the prototype stage of development, it allows the cartographer to locally adjust several shading parameters, including light direction.

For applying local adaptations to shaded relief, the software uses the concept of fences, an interface metaphor borrowed from CAD applications. To use fences, the user draws a bounding enclosure to isolate a portion of a DEM. Within the fenced area parameters are adjustable to locally alter the appearance of the shaded relief.

Shaded relief without local adjustment Shaded relief with local adjustment

Local adjustment of the light direction. Left: A mountain ridge illuminated from the northwest. Right: A fence containing locally adjusted illumination from the southwest.

The before and after figures above illustrate locally adjusted light direction applied within a fence. By locally replacing the main northwest light source with one from the southwest, the northwest trending mountain ridge is better depicted.

The images below compare a manual shading with an analytical shading that employs locally adjusted light direction and brightness parameters.

Manual shading of Rigi Analytical shading of Rigi with local adjustments

Left: Manual shading. Right: Analytical shading with local adjustments.

Analytical
DEM
Shading Methods
Flat Areas
Local Adjustments
Aerial Perspective
DEM File Formats