Part 1) Introduction

Terragen is a scenery generator, created with the goal of generating photorealistic landscape images and animations. It is available for Windows and the Mac OS. Although there is a paid version presently Terragen is free for personal, noncommercial use.

One of the many ways I utilize Terragen is in generating skyboxes. Skyboxes for games serve as a backdrop for a level or map.These allow you to add a special touch to your levels. You can change the mood of a level simply by the time of day, or season portrayed in the skybox.

In this tutorial I will show you how to make a 6 sided skybox for that use, or just for your enjoyment. In Terragen there are 5 buttons that control the world scene characteristics. We will take each one, and give general ideas of usage. In this tutorial I am presuming you have some working knowledge of Terragen already. If you do not take some time to play with these settings, and become familiar with how each effects the wordl scene.

Part 2) Creating the Skybox

When you open Terragen you get the first two control windows opened: Landscape and Render Control. Go first to the Render Control, click on the Camera Settings, and adjust the Zoom to 0 only. This will make it so your sides all line up in the completed box. Adjust the Image Size to something equal on all sides (256x256, 512x512, 1024x1024, etc.). It has to be equal to make for a proper fitting "box". For purposes of this tutorial I am going to be using 512x512. {Fig.1} & {Fig. 1a}

Keep in mind, the larger the image size the more seamless the result of your skybox, in some games. You may want to research what is best for your particular project. Once image size is set for the original, resizing them in other applications really does create distortion.

The Landscape button is the first in our list. To begin we need to create the terrain, or you can use a pre-existing terrain. Pre-existing terrains can be found on various graphic sites. There is also an acompanying application called World Machine that makes landscapes for Terragen.

To create your own terrain though will give you a chance to play with the various sculpting tools, and terrain builders in the program. You will find it is easy to manipulate the terrain to what you would like it to look like. {Fig.2}

Click on Generate Terrain, and another window will appear. It is in this window you will select what kind of terrain you want to use as a base. For me I am using MultiPerlin, but there are 5 to choose from. Then you can still sculpt and re-create it to be all your own. Notice the other settings that can be altered here as well. Combining terrains, size, canyonism, glaciation, smoothing and realism can give you the chance to make something totally unique. Take time to play with and decide which suits your needs for your world scene. {Fig. 2 above}

Now you can add some texture to the terrain. Click the open surface map button at the right and let's take a standard surface map, or you can make your own by clicking on the Surface, and then Edit. {Fig. 3} You can create any colors or textures you can imagine. This is something that will take more time if you do not want to use a default to begin, and then alter. Everything depends on what you would like to do with the terrain, and the end result you want to achieve.

Next you may want to add some water to your skybox. Go to the left nav bar, and select the Water button. This also has many variables to choose from. You can select the depth, colors, foam, reflection, etc. The options are almost endless in combinations. Click on the Update Map button, and you can get a preview of how much land area is covered by the water. If it is not to your liking, simply change it. Here I show the image as rendered with water. {Fig. 4} & {Fig. 4a}

Clouds are the next panel to check out. This one is fairly easy, but can get complex if you want to make it so. You can do layers of clouds in either 3D, or simple. This has a preview screen with some settings we can adjust. The sky size can be adjusted here, but it will increase your rendering times. Also if you have a black edge around your scene raise the sky size, and those will disappear. {Fig. 5}

Play with the 2D versus the 3D clouds to see which you prefer. I mostly use the 2D clouds, just because I rarely see a difference in the two once in the scene. Adjust the Density contrast slider, and this will make the clouds look sharper. Density shift alters how much of the sky will contain clouds. Sliding to the right will make for a totally clouded sky, to the left for no clouds at all. {Fig. 5 above}

Next up is the atmosphere. This includes the sun, clouds and light characteristics in your scene. This can determine the time of day/night, the colors and how they react to each other, as well as how realistic the image appears. The only limit in this is how far you want to take it. This is the one that is more complex of all the settings. {Fig. 6}

Within the Atmosphere are Simple haze, Atmospheric blue and Light Decay/Red are the specs in this tab.

*The Simple haze makes the glow around the sun, simulates atmospheric dust, fog and water. Its always the same colour of the clouds as this is linked to each other.The density slider defines how much you will see of this effect. Half height slider defines the heights at which the atmospheric components are half as dense as they are at an altitude of zero.

*Atmospheric blue creates the blue appearance of the sky, but also plays off of other items in the scene.

*Light Decay/red is when the light passes through the blue light and is scattered throughout the scene. The Lighting conditions button is linked to the Atmosphere button. If you look in the Lighting button you will see the same settings as in the Atmosphere. The sun settings panel gives the ability to give the sun some characteristics of our own. Here you can give the time of day to your scene. You can pick the colour, strength, background light, appearance and corona size/glow of the sun. Here too you can make it appear to be nightime or give moon characterisitcs. {Fig. 6 above}

Once you have the World scene as you want, left click on the center of the image preview window, and then right click. This places your camera in the center of the box. Now we need to save 6 sides of the image from the various angles of the scene to form our box. {Fig. 7}

Saving the images in Terragen is a default of .bmp. Once done you can open them in any graphic program, and save them as whatever type you need (jpg, tga, png, etc.) Setting the image Quality will play a part in how long the render time is going to be. The more detailed the longer the time. The paid version has a few more selections in this area. Depending on what is in my scene I can see a quality difference.

Once you have all the settings for that particular side, click on the preview first. Make sure it looks as you would like, and should, then click on the Render Image. Once it is done a small time window will display. This tells you all the pertinent info for that image side, like render time and quadrilaterals. {Fig. 8}