| On this page |
Terraces are topographic features, not layers. They form when a river or sea cuts into an older level, leaving behind flat, step-like ledges. Common types include:
-
River terraces are former valley floors that have been “exposed” by river erosion
-
Marine terraces are former coastlines made visible by tectonic uplift or sea level fall
The typical V-shape of river terraces is the result of erosion processes of varying duration. Near the surface, the rocks were exposed to erosion for a longer time and more of the rock has weathered. The eroded material slides down the valley and is carried away by the river at the bed of the valley.
When you think of terraces, you might imagine huge structures like canyons. However, terraces also occur in relatively small areas like the banks of a creek. To sum up, one can say that terraces are a good method to enhance your terrain’s overall appearance and mimic topographic features.
Out of the box, Houdini’s terraces often look artificial, because they have hard edges. That’s why terraces are typically combined with other nodes and masks to give them a natural look. Even for man-made structures like the famous rice terraces in South Asia, it makes sense to add a slight amount of blurring or some mild erosion.
Houdini’s terraces are always horizontally aligned and there’s no default method for changing their orientation. The height of Houdini’s terraces is also fixed and you need custom solutions to art-direct this feature.
Adding terraces ¶
The node for creating terraces is the 
HeightField Terraces COP. You can add this node anywhere inside your network, but you need at least a terrain, for example a 
HeightField Noise recipe. It’s also possible to use multiple terrace nodes with different masks and parameters.
By default, the node creates terraces between a terrain height of 10 and 100 meters. This is the masked area and displayed as a red band on your terrain. To modify this band, change the HeightField Terrace SOP’s Min Height and Max Height parameters. If you're not sure about working values, click Compute Range.
Method lets you choose whether you want to define a fixed Step Size (“height”) for the terraces. You can also add variation with a Random Step parameter to avoid an artificial or uniform look. With Number of Terraces, you can exactly define how many terraces you want to create between Min Height and Max Height. Again, Random Step lets you vary the individual height of the terraces.
When you turn on Add Layers, it’s possible to further subdivide the terraces to break regular patters. You have random seeds to create different looks. The Layers parameter defines how many intermediate terraces you’ll apply.
Mesa and cliffs ¶
The HeightField Terrace COP outputs two layers called mesa and cliffs. The mesa layer (left image) contains the horizontally clipped areas of the terraces. The cliffs layer (right image) represents the vertical parts.
Erosion and slump ¶
The HeightField Terraces COP creates rather regular and horizontally aligned structures. When you add a 
HeightField Erode COP, you’ll be able to break the patterns and blend the terraces with the terrain. However, erosion sometimes tends to erase the terraces almost completely. In such cases it’s necessary to adjust erosion parameters like Iterations and Feature Size. Decreasing Erodability is also a good way to conserve as many structures as possible. Erosion masks can also help to protect the terraces.
Adding slump with the 
HeightField Slump COP is another way to improve the look of a terrain’s terraces. You typically use masks to restrict the creation of slump to specific areas.