## Using Terragen to create fractal landscapes

Terragen is a program that lets you create photorealistic fractal landscapes, such as the one you see on the right side of the screen. Terragen does not use any digitized images to create the landscape. Instead, it uses fractals to model the mountains and clouds. It also uses raytracing to determine the interaction of light with the objects in the scene.

In addition to random fractal landscapes, Terragen also permits you to sculpt your own landscapes. In addition, it is possible to import GIS data into Terragen and thus recreate actual terrain. The freeware program LandformerPro can accomplish this task.

I have used Terragen in my PHY-125 class (Science through Film and Fiction) as a demonstration of the power of equations to model the real world. The noted 19th century physicist James Clerk Maxwell said, "Physical science is that department of knowledge which relates to the order of Nature." In this case, the "order of nature" means that natural phenomena obey simple mathematical principles. We can use the order present in the natural world to construct a mathematical model of reality. We then use that model to carry out experiments in our virtual virtual world. If the model works well, then we accept it and use the model to help us understand the real world. If the model works poorly, we change the model until it reproduces the effects in nature that are of interest. For example, we can use the Terragen model of the world to refine the proverbial question, "Why is the sky blue?" and ask, "What makes the sky a particular shade of blue?" Likewise, we can ask why sunsets are red, and then further refine the question to ask why sunrise looks different than sunset.

I have created a short tutorial on how to use Terragen to create fractal landscapes. This tutorial was written for Windows, but it is pretty similar for the Mac. This tutorial will explain how to create a fractal landscape and how to apply a surface map to that landscape to cover the ground with grass, snow, water etc. It also discusses how to create clouds, orient the sun, and change the properties of the atmosphere.

I have also created a tutorial on using Terragen 2 to create fractal landscapes. Terragen 2 gives you far more control over the features of the landscape, but it also requires more time to learn how to use. This tutorial is for version 2.4 of Terragen 2 for Windows, but the tutorial should be pretty similar for the Mac. This tutorial explicitly incorporates trees into the landscape, in addition to grass, snow, and water.

There is also a Terragen 3 tutorial. Terragen 3 is very similar to Terragen 2, but is somewhat easier to use and contains more features.

There are many online tutorials that can help you use the more advanced features of Terragen. You will probably want to start with the official Terragen User Guide . It describes all the controls in far more detail than my brief tutorial.

Carol Brooksbank has written a series of tutorials on Terragen, although her tutorials are based on older versions of Terragen, so they won't cover all the features in the current version. Other than that, her tutorials are quite comprehensive. One of the things she covers is how to make animations using Terragen. As you can see above, it's not that hard to create a Terragen animation, although I should warn you that it takes quite a while to render an animation. She also covers how to make night scenes in Terragen.

A tutorial on using GIS data with Terragen 2. The final rendered image is quite impressive.