Written by Katrina Schweikert
Global Mapper® provides a variety of ways to apply sunlight or scene lighting to the map view, whether it is to create stunning visuals or to perform analysis based on sun angle. In this article, we explore some of the options for working with light across a variety of different types of data.
Hillshading is an effect applied to terrain data in order to see the structure of the landscape. It uses shadows to show the terrain’s texture, such as slopes, hills, and valleys. This is also referred to as shaded relief because shadowing accentuates the relief of the terrain, even though the image, in reality, may be 2D. Hillshading works with terrain data in the 2D and 3D views and can also be applied to cartographic outputs like printed maps or digital images.
Hillshading is enabled by default when terrain data is loaded into Global Mapper and can be toggled on and off from the toolbar. The hillshading effect is visible in both the 2D and 3D views. It may not necessarily be accurate for the location of the dataset because the default position of the sun for the hillshading is to the north-east. This sun angle creates a cartographic effect, in which most people will see mountains and hills extruded towards the viewer and valleys appearing indented. Moving the sun to another position will sometimes confuse the brain about the depth of certain parts of the terrain. Nonetheless, it is very useful for realistically modeling how the sun might hit the landscape. There are numerous sites on the internet that can provide the sun azimuth and altitude information for a specific location at a given date and time for modeling real-world conditions.
The hillshade can also be applied to a custom terrain shader. In the below example a custom terrain shader was built replicating a palette similar to those used by Eduard Imhof in his famous shaded relief maps.
Another option for working with hillshade is to apply the hillshade to an image or another raster layer overlaying the terrain. The quickest way to do this is to use the Texture Map option, however there are also several blending modes that combine an image layer with the underlying hillshaded terrain.
Additional Light Controls
The Dynamic Hillshading tool provides additional control over the lighting of the scene. Many of these settings also impact the lighting effect in the 3D view. Ambient lighting can be used to enhance the overall brightness of the terrain layer and how much sunlight touches the terrain. Shadow darkness and highlight settings impact how black shadows and white highlights are rendered within the hillshading pattern. The Vertical Exaggeration feature amplifies the 3-dimensional nature of the landscape with the shaded relief by exaggerating the effect of lighting on the terrain.
From the Dynamic Hillshading tool, it is also possible to add multiple light sources. With varied datasets such as terrain, 3D vectors, and 3D models combined into one scene, adding multiple light sources helps illuminate the various parts of the scene.
Eye Dome Lighting
Eye Dome Lighting was added to Global Mapper with the release of version 22. This is a lighting effect that specifically applies to the 3D Viewer and is used to accentuate depth within the scene. Data in the middle ground of the scene that is three-dimensionally offset from surrounding data is given a shadow outline. This provides the viewer with a better sense of features extruding from the ground.
Within the 3D view configuration dialog box, the strength and radius of the Eye Dome Lighting effect can be adjusted. There are also several falloff options that define how the shadowing fades out across the radius.
If you would like to explore this functionality in more detail, or familiarize yourself with any other new features in Global Mapper, request a two-week free trial today. If you would like to speak with a representative about how the software can address your unique geospatial challenges, request a demo.