The problem of representing three-dimensional geographic information is not new to cartographers. In this lesson, we have already discussed some techniques that cartographers commonly use for this task, Isolines and Shaded Relief. In this concept gallery item, we will focus on other techniques for visualizing 3D data.
The software tools and techniques that are available to cartographers for 3D visualization are rapidly changing as new techniques and even new programming languages are developed. For this reason, we will structure our discussion of 3D visualization methods by discussing several attributes that we can use for classifying methods and techniques.
One of the most basic distinctions that we can use is whether the method uses a perspective view of the 3D space, or whether it is an immersive view. In a perspective view, the map reader is outside of the space and looking in at it, while in an immersive view, the map reader feels like s/he is actually within the space. An example of a perspective view can be seen in the rotated TIN and shaded relief images shown earlier in this lesson. This type of perspective view can be easily created with standard GIS software. More immersive views can be created by 'flying' over or through a perspective view (e.g., using GeoVRML, the geographic virtual reality modeling language and an internet connection) or by using specialized virtual reality software that projects images onto screens that physically surround the viewer (e.g., the CAVE virtual reality environment).
Figure 6.cg.40 and Figure 6.cg.41 In the example above, at left, augmented reality provides a perspective view that the map reader can rotate (Hedley et al. 2002), but does not provide the true immersive perspective found in the CAVE environment (above right) (Johnston and Reetz 2004).
To get a better simulation of the experience of using the CAVE, Play the movie below. It shows user interactions with the CAVE (Johnston and Reetz 2004).
Movie tracking user movements in the CAVE environment.