Use the Smooth Height tool to smooth the heightmap and soften Terrain features. In the Terrain Inspector, click the Paint Terrain icon, and select Smooth Height from the list of Terrain tools.
The Smooth Height tool does not significantly raise or lower the Terrain height; instead, it averages out nearby areas. This softens the landscape and reduces the appearance of abrupt changes.
For example, smoothing is useful after you paint with brushes containing high frequency patterns. These brush patterns tend to introduce sharp, jagged edges into a landscape, but you can use the Smooth Height tool to soften that roughness.
2019–01–29 Page amended with editorial review
Updated functionality in 2018.3