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..::blending landscapes into the horizon::..

Designing the layout of an encompassing scene is all about planning. Granted, the client may change his or her mind later on, but overall it’s best to cover those eventualities in advance just in case they occur! Assuming your scene is set above ground, the space between the ground and the sky would be air which, if you view real-world scenes, affects the saturation of an object the further away from the camera it is positioned. The ground can be any shape or form you wish, as long as it stretches far away to your horizon line. If you’ve already created your scene and need to increase the distance of the horizon, create a second larger plane beneath the first and apply an opacity to the first to remove any harsh lines that may appear at render times. Failing that, amend the mapping of the ground plane and pull the extents far out to the horizon, adding more refinement and detail if so required (possible extra use of decal textures could be applied here to break up any repeating textures on the base material).

The sky should typically be a hemisphere Geosphere, mainly because of it’s consistent face sizes and low polygon count. This should entirely encompass the scene and ‘meet’ the ground object. The sky texture should be applied to this using cylindrical mapping, but without any additional fading to white on the source material; this will be handled later on by one method or another. If required, the sky could be separate planes stretching off into the distance to create individual cloud layers, which could then be animated. These could then be deformed (along with the ground plane) to create the slight curvature of the surface that creates a horizon.

To remove the harsh horizon line, we can do this using two main methods. The first is the easiest and most commonly used, but offers less control over the settings. This is of course environment fog. This is produced at render time with the effect generated from settings taken from the camera the scene is being viewed from and the main environment rollout. The camera’s far range setting should be set so the range is well past the horizon line, else the line (and most of the sky) will appear white. The other method, and one not commonly used, is a material effect. By mixing the entire scene’s materials with a near white self-illuminated material, we can then control it’s opacity using a radial gradient that stretches out to the horizon and using mapping that has it’s Gizmo linked to the camera to fix it’s position and maintain the effect should the camera move. By tweaking the gradient’s key’s positions we can, if we apply a separate linear gradient to the sky hemisphere, design our ‘fog’ to suit our scene more quickly and easily than using an environment effect. Granted, this method may not initially work with animated objects it is possible to modify it, and gives an overall effect that can be amended simply and can even affect the colour of the fog depending on the distance from the camera and/or it’s scene’s surroundings.

Enlarge ScreenshotUsing camera ranges extended beyond the scene, the environment fog increases further away from the camera. Note the sky is also de-saturated, slightly too much.
Enlarge ScreenshotUsing the material method gives us greater control in this scene. We can control the ‘fog’ using gradients to mix the white with the scene textures and to add additional effects.

Initially published: 3D World magazine, Issue 21, January 2002.

Copyright © Pete Draper, January 2002. Reproduction without permission prohibited.