Erode
Carve channels and deposit sediment on an image with hydraulic and thermal erosion.
What it does
Erode runs a hydraulic and thermal erosion simulation over an image, treating brightness as height: bright is high ground, dark is low ground. Water rains onto the surface, flows downhill, picks up material and deposits it elsewhere, carving branching channels. With thermal erosion enabled, slopes steeper than a set angle also collapse and slump.
The input need not look like terrain. Noise, a mask or a gradient produce organic drainage veins, weathered edges and flow-carved transitions. A Mask input protects areas from erosion entirely.
When to use it
Organic, branching channel or vein patterns from noise or a gradient.
Naturally weathered or worn edges on a mask or shape.
Terrain-like relief carved into a heightmap-style image.
Protecting part of the image from erosion, by wiring a Mask.
| Parameter | Type | Default | What it does |
|---|---|---|---|
content_in | Raster | — | Image to erode. Luminance is treated as height — bright = high, dark = low. |
mask | Raster | — | Mask controlling where erosion occurs. White = full erosion, black = protected. |
iterations | Number | 50 | Number of erosion iterations. More = deeper erosion. |
rain | Number | 0.010 | Rain rate — water added per cell per iteration |
erosion_rate | Number | 0.300 | Erosion rate — how aggressively water picks up material |
deposition_rate | Number | 0.300 | Deposition rate — how quickly material settles |
evaporation | Number | 0.020 | Evaporation — water loss per iteration (lower = longer rivers) |
capacity | Number | 1 | Sediment capacity — how much material water can carry (proportional to speed) |
enable_thermal | Boolean | false | Enable thermal erosion (slopes steeper than talus angle collapse) |
thermal_rate | Number | 0.500 | Thermal erosion rate |
talus_angle | Number | 0.600 | Talus angle — max stable slope (tan of angle). Lower = more aggressive collapse. |
strength | Number | 1 | Effect strength / wet-dry (0 = no effect, 1 = full). Editable, wirable, keyframable. |
Gotchas
Thermal erosion is off by default. Turn on Enable Thermal to reveal Thermal Rate and Talus Angle. Without it, slopes never collapse and only hydraulic channels form.
Besides the eroded image on the main output, Erode has three more outputs: Flow, Sediment and Erosion Delta. They carry per-pixel simulation data, flow accumulation, deposited material, and net material removed or added, so they look like encoded data rather than a picture.
Lower Evaporation to make water travel further before drying up, which produces longer, more connected river-like channels. Raise it for short, localised trickles.
Worked example
Add an Erode node and wire in an image. A noise field or gradient works well to start.
Raise Iterations for deeper, more developed channels. Keep Rain and Erosion Rate moderate at first so the effect does not over-carve.
Lower Evaporation to connect the channels into longer, branching rivers.
Turn on Enable Thermal and adjust Talus Angle to make steep areas slump and soften instead of staying sharp.
Wire a Mask into Mask to keep specific areas untouched.
See also
Displace · Slope · Spread · Rasters (images)