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For those who never heard about it, Relief Shading is a cartography rendering technique where a three dimensional appearance is given to the topography of a map. The execution of this technique is quite complex and it is usually achieved using special map rendering software.
Despite of that, many articles have been written about Relief Shading in Photoshop. These articles are somewhat complex and are usually directed to cartographers and map artists. That’s because they use very precise topological data and any change in the representation can result in misleading cartographic information. This tutorial will attempt to bring Shaded Relief to the rest of us who sometimes need to create a fancy map for a brochure or a terrain for a video or board game without the need of an exact topological data representation.
The images above belong to ReliefShading.com web site.
In the case that you have to render an existing location, the first thing you have to do is to get the elevation data of the map, which is know as DEM (Digital Elevation Map).
Currently, Adobe Photoshop can’t open DEM files directly. You have to open them as RAW files. Of course, you have to know the size of the image and other information to do so.
DEM files are available all over the net but they are mostly commercial. Of course, there are lots of free resources which are mainly from .gov web sites. The problem with DEMs is that they are available in many different formats and they are huge 16bit files. So, you’ll have to make a research for the map you are looking for and ask how it can be opened with Adobe Photoshop.
Luckily there is an easier and free way to obtain ready to use DEM maps using the USCG seamless data distribution online application, but I will explain that at the end of this article. For this tutorial, I will use the following image I extracted from that application. Don’t worry about the location. For this example it is not important to be precise with the real geography, we’ll just concentrate in the relief of the map. I’ve even retouched the image to make the water bodies and rivers more visible.
In this image, each shade of gray represents a height in the final rendered map, being white the highest height and black the lowest height. In fact, any grayscale image can be used as a Digital Elevation Map. It is just that real height maps look better than faked height maps, unless you are trying to achieve a “unreal” look.
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