Houdini 20.0 Nodes Geometry nodes

HeightField Erode Hydro geometry node

Simulates the erosion from one heightfield sliding over another for a short time.

Since 17.0

Flow erosion can be used to simulate anything from rainfall, where the flow of water downhill weathers the terrain, to the grinding effects of a gravel layer sliding along a rock layer.

Parameters

Erosion

Global Erosion Rate

Controls how many meters of the eroding layer or material layer is eroded every iteration.

Erodability

Controls the softness of the eroding layer or material layer. Higher values would make the terrain easier to erode, causing deeper incisions, more sediment, and more debris being deposited as a result.

erodabilitymaskmode

Controls whether to use a mask for erodability or not.

Erodability Mask

The name of the erodability mask.

Erosion Rate

Controls the rate at which erosion happens. This is a multiplier on Erodability.

Removal Rate

Proportion of debris from thermal erosion that is deleted. This simulates wind carrying away a certain amount of debris rather than it all accumulating. The default is 0 (no deletion). Negative values correspond to the debris being less dense than the rock, so one unit of eroded rock produces more than one unit of debris.

Bank Angle

Sets the angle at which the riverbank rests relative to the riverbed. Lowre values would make wider and flatter river channels.

bankanglemaskmode

Controls whether to use a mask for bank angle or not.

Bank Angle Mask

The name of the bank angle mask.

Random Seed

Random seed to make erosion vary for the same set of variables on the same input.

Adavanced Erosion

Removal Rate

Proportion of debris from thermal erosion that is deleted. This simulates wind carrying away a certain amount of debris rather than it all accumulating. The default is 0 (no deletion). Negative values correspond to the debris being less dense than the rock, so one unit of eroded rock produces more than one unit of debris.

Max Debris Depth

Stop erosion when the debris layer reaches this depth.

Erodability

Ramp-up Iterations

The iteration where erodability would get to its maximum value.

Initial Factor

Controls how much of the set erodability would the material have on its initial movement. It would increase over the set spread iterations until the max iteration, where it would stay at maximum set value.

Slope Factor

Control how much the slope of the terrain would affect the erosion amount. Higher values would increase the slope effecting the erosion, and lower values would decrease it. Lowing this value would increase erodability as a result.

Riverbed

Erosion Rate Factor

A multiplier on Erosion Rate that would cause a change on the riverbed only. Increasing this value would cause a more aggressive erosion on the bed, and as a result, it would increase the depth of the incisions.

Deposition Rate

Controls the rate at which the excess sediment turns into debris. A value of zero means no sediment is turned into debris, while a value of one will convert all created sediment into debris, and the bedrock would in turn be protected more by the created debris.

depositionratemaskmode

Controls whether to use a mask for deposition rate or not.

Deposition Rate Mask

The name of the deposition rate mask.

Sediment Capacity

The amount of sediment that can be carried per unit of moving water. The higher the capacity, the longer the material can erode before it starts depositing its excess sediment.

Riverbank

Erosion Rate Factor

A multiplier on Erosion Rate that would cause a change on the riverbank only. Increasing this value would cause a more aggressive erosion on the bank, and as a result, it would increase the width of the incisions.

Max Bank to Bed Water Ratio

The maximum of bank to bed water column height ratio that will be considered as river bank bank. Ratios higher than this number will not be considered as bank during erosion.

Flow

Grid Bias

Controls how biased the movement of material is. Setting it to positive values would bias the movement in the direction of the principal axes, and when set to negative values, it would bias the movement at angles of 45 degree relative to the principal axes. The default value of zero would mean no bias in any direction.

gridbiasmaskmode

Controls whether to use a mask for grid bias or not.

Grid Bias Mask

The name of the grid bias mask.

Quantization

Controls the chunkiness of the material flow. A lower value would make the flow more continuous and a higher value would make the flow more chunky.

Spread Iterations

How many iterations of slumping to simulate. Fast-moving slump layers like water or gravel should use a higher value, while lava or rock should use a lower value.

Layer Bindings

The controls on this tab let you change the default names of the layers the node looks for/creates.

Slump Layer

The name of the layer that flows, and causes erosion by its slumping (default water).

Debris Layer

The name of the layer that will be dragged along with the movement of the slumping layer (default debris).

Sediment Layer

The name of the sediment layer where the eroding layer will be turned into before being deposited into the debris layer (default sediment).

Eroding Layer

The name of the layer that will be broken into the entrained layer by the action of erosion (default height).

Below Layers

When eroding a system with more than two layered heightfields, the effective height at a point may be the sum of multiple heightfields. This is a space-separated list of of all the layers below the Eroding Layer (default ).

Bedrock Layer

The reference layer for determining how far the current height has eroded. If not present on the input, is set to the original height of the terrain.

Mask

The name of a mask layer to use as the erodability value for each point on the terrain. A value of 0 allows no erosion (use this to represent something like granite). A value of 1 means easy erosion (use this to represent loose dirt). This is read from the second input.

Strata

Adjust Erodability by Strata

Adjusts how erodible rock is by how far it is away from the reference bedrock layer.

Strata Depth

The depth for the strata. The Strata Erodability ramp uses this depth to control how deep it represents. A positive values means the strata represents hardness below the bedrock layer. Negative values mean the strata represents hardness above the bedrock layer.

Clamp at Strata Bounds

Depths outside of the strata range will be clamped to the ends of the ramp. If clamping is off, they will repeat forming a periodic pattern.

Strata Erodability

How erodible rocks are at different strata depths. The left most is at the bedrock reference layer, the right most at the extreme strata depth. Values of 1 are fully erodible, such as loose dirt, and values of 0 prevent erosion, like granite.

Geometry nodes