Terrain Dialog

image of landscape dialog

The Terrain Dialog is the usually the first part of Terragen you will encounter. Here you can generate the terrain (or open existing ones), modify it in various ways or perform arithmetic with other terrains. You can also modify the surface map.

B&W/Cols. The heightfield map is drawn either with black & white shading or by colour shading. In both the images on the right, the leftmost colours represent low altitudes, and the rightmost colours represent high altitudes. Black and white shading is the default when the program starts. black and white gradient
colour gradient

*Camera/Target Positioning. Using this mode you can position the camera and the point that the camera is looking at. By clicking on the large terrain view with the left mouse button you can choose the camera position, clicking with the right button chooses the target. For more information see the Render Form.

*Sculpting Tools. There are three sizes of sculpting tool - Large, Medium and Small. When you click or drag with this tool you can raise or lower the terrain where you click. The left button raises the terrain, right button lowers it.

Import/Export of Terrains. You can import/export terrains as a raw binary file (8 bit per pixel) of resolution 257*257. You can also export the terrain in VistaPro-compatible binary format (16bit Motorola encoding RAW file of resolution 257*257). The RAW option is very useful as it allows you to create grayscale images in a normal paint program and import them as landscapes. There are utilities that will enable you to convert USGS DEM (digital elevation map) files for import into Terragen to allow you to render real-world scenes. For more information, see Matt's Terrain Resources page.

Terrain Genesis

image of terrain genesis dialog

Method. The method used to generate the terrain. Normally you should use Subdivide & Displace as the Perlin Noise method is not as realistic as yet. For details on how the Subdivision Method works, see the Planetside page. The Perlin method can be used to create more realistic landscapes if you canyonize and glaciate afterwards (see Terrain Modification), which are especially suitable for mountain scenes. Ridged Perlin is an extension of Perlin Noise, and creates landscapes with more ridges(!). There are also Multi- versions of Perlin and Ridged Perlin now available which seem to generate more craggy, irregular landscapes. The best thing is to experiment until you find results that suit you.

Action. Normally you will want to Erase First and generate new terrain. This starts from scratch with a new terrain. Generating features on the existing terrain generates a new random terrain and combines it with the existing terrain.

Realism. A higher setting generates a more realistic terrain with smoother transition between high and low. A lower setting can be used to create a more "craggy" landscape. Only available for the Subdivide & Displace method.

Smoothing. Adjusts how smooth the landscape will be. Setting this too high can interfere with the realism setting and create unwanted results. Only available for the Subdivide & Displace method.

Glaciation. Modifies the landscape by flattening valley bottoms and smoothing sharp changes in gradient.

Canyonism. Sharpens the valley bottoms, creating an effect similar to canyons in the desert (although usually not quite so pronounced)

In many ways, Glaciation and Canyonism work against each other. Applying both during the creation process can create a more realistic, balanced landscape as you might find in nature. If you wish to create an image of desert canyons you might wish to set glaciation low, and canyonism high, etc.

Size of Features. This slider controls how large the hills are, both in horizontal and vertical size.

Perlin Origin. Used in the generation of Perlin landscapes (and the Perlin variants). You should usually use the "random origin" feature unless you want to reproduce an earlier result. By changing these values slightly, you can move the landscape in small increments, which is useful when you have created a landscape with nice features which are partly out of view.

Terrain Modification

image of terrain modification dialog

Bound Vertical. Scales the terrain so that it ranges between the values given.

Scale Vertical. Scales the terrain by the percentage factor given. The Stretch button sets the scale value to 133.33%, and the Squash button sets it to 75%. Even after pressing the Stretch/Squash buttons, you still need to press the Scale Vertical button.

'Glaciate'/'Canyonize'. Applies Glaciation/Canyonization to the current terrain. This is different from applying these during the terrain generation process, where the effects are carried out half-way through the subdivision process.

Clear / Flatten. Clears the terrain.

Terrain Combination

image of terrain combination dialog

This dialog box can be used to combine two terrains in a more sophisticated way than the "Generate on top of existing" feature. There are four options - Addition, Subtraction, Highest and Lowest, with smoothing options for Highest and Lowest. The Combination Preview shows the result of combining the landscapes, colour coded to show whether the primary or secondary terrains are dominant for a particular position in the landscape.

Surface Map

I apologise about the appalling explanation about Surface Maps. However, it is a very hard concept to explain! Mike Nightingdale and Rainer Dückerhoff have written Texture Help, which gives some more information, with emphasis on snowy scenes.

Before you can start editing the surface map, you have to click on one of the items in the surface map "tree".

The surface map works by a heirarchical system. At the top of the tree there are always two "children", which can either be surface colours or a subtree in itself. A subtree again contains two children.

To create a subtree from a bottom level (colour only) item, click the "split" button. A subtree is now created, with one of the sub-surfaces being darker than the other. You can now edit this subtree like you would a top-level tree. Subtrees are essential when more than two colours are needed (e.g. grass, snow and rock).

The Rename button is there for a reason! When creating complicated surface maps, it is easy to lose track of what surface is what if you don't name them something useful.

Subtree distribution settings

image of distribution settings dialog

To help you see better the distribution for altitude, slope aand surface modifier map, the small previews are shown in black and white. You can turn off any of these distributions (the Effective checkbox) or reverse the effect (Negative Correlation). The Effectiveness slider controls how much each of the distributions play a part in the overall distribution. The best way to obtain ideal results is to experiment, and see what happens on the Overall Surface Distribution preview.

Altitude. Varies by altitude which of the children should be more prominent.

Slope. As Altitude, but varies by the slope of the terrain.

Surface Modifier Map. This adds randomization and therefore a more natural feel than just distributing the children by altitude or slope alone. This should almost never be turned off.

Overall Surface Distribution. This gives a preview of the distribution, and allows you to bias towards one of the two children.

Surface Colour

image of colour picker

With this dialog you can change the colour of any surface. The Photographic Preview shows how the colour would look under a variety of exposure settings.



render controls

landscape

water

clouds

atmosphere

lighting

image
menu items - working with files - faq - getting started - moonscapes - animations - post-processing - index
©May, 1999 John McLusky