Image: Height Fields & Terrain#

Height field generation, erosion, masks and terrain tools.

22 nodes.

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Contents#

• COP Curvature (PCG) — Computes surface curvature of a height field, positive on convex areas.
• COP Erosion Filter (PCG) — Adds erosion-like gullies and ridges to a height layer in a single, per-pixel pass; it is a filter, not a simulation.
• COP Flow Accumulation (PCG) — Computes how much upstream area drains through each pixel of a height field, and derives river, lake and flow direction layers from it.
• COP Height to AO (PCG) — Computes ambient occlusion from a height field, where 1 is unoccluded and 0 is fully dark.
• COP Height to Caustics (PCG) — Simulates the light patterns a water surface focuses onto the bottom, from a height field used as the water surface.
• COP Height to Normal (PCG) — Converts a height layer into a tangent-space normal layer (signed, +Y up, OpenGL convention).
• COP Height to Shadow (PCG) — Casts sun shadows over a height field, optionally with soft edges.
• COP HeightField Clip (PCG) — Clamps a height layer into a minimum/maximum range, optionally with a soft knee.
• COP HeightField Cutout by Object (PCG) — Carves the terrain down to the bottom of a geometry, fills it up to its top, or both.
• COP HeightField from Depth (PCG) — Turns a single image's depth into a top-down height field, so a picture of a landscape can feed the terrain chain.
• COP HeightField Hydraulic Erosion (PCG) — Erodes a height layer with simulated water droplets that carry and deposit sediment.
• COP HeightField Mask by Feature (PCG) — Builds a mask from terrain features: slope, direction, height, curvature and occlusion.
• COP HeightField Mask by Object (PCG) — Projects a geometry vertically onto a height field and outputs a mask of where it covers, crosses, floats above or is buried below the ground.
• COP HeightField Project (PCG) — Projects geometry down onto a height field, or, with no geometry connected, transforms the height field in 3D and projects it back.
• COP HeightField Splat Map (PCG) — Derives a set of grass, sediment, rock, snow and water material masks that sum to one from a terrain.
• COP HeightField Stream Power Erosion (PCG) — Erodes a height layer by simulating the stream power law with an implicit solver.
• COP HeightField Terrace (PCG) — Turns a height layer into terraces with flat treads and steep risers.
• COP HeightField Thermal Erosion (PCG) — Collapses slopes steeper than the angle of repose, moving material downhill and piling it up at the foot.
• COP Mono to HeightField (PCG) — Converts a single-channel layer into a height layer by scaling and offsetting its values.
• COP Normal to Height (PCG) — Reconstructs a height layer from a normal map; the inverse of Height to Normal.
• COP Slope & Aspect (PCG) — Computes slope, aspect and downhill direction from a height layer.
• COP Strata (PCG) — Adds tilted rock strata to a height layer as terraced layers with random hardness.

Nodes#

COP Curvature (PCG)#

PCG_COPCurvature · category PCG/cop · Houdini: Curvature (COP)

Computes surface curvature of a height field, positive on convex areas.

The height layer (multiplied by Strength) is treated as a surface over a world width of World Size. Curvature is in 1/world units and convex is positive (peaks and ridges above 0, pits and gullies below 0).

• mean: mean curvature.
• gaussian: Gaussian curvature (saddles are negative, independent of convexity).
• profile: curvature along the slope direction; negative where the slope steepens, positive where it flattens.
• tangential: curvature across the slope; positive on ridges, negative in gullies.
• plan: curvature of the contour lines; positive where flow diverges, negative where it converges.

To separate ridges from gullies use tangential or plan rather than elevation, which gives wrong results for gullies on high ground and ridges in low ground. Scale is a final multiplier: curvature scales with 1/R, so multiplying by a characteristic length gives a dimensionless value that is convenient as a mask. (profile + tangential) / 2 equals mean.

Inputs

Outputs

Parameters

Tips

• Multiply with Scale by a characteristic length (for example World Size / 20) to get a dimensionless mask.

COP Erosion Filter (PCG)#

PCG_COPErosion · category PCG/cop

Adds erosion-like gullies and ridges to a height layer in a single, per-pixel pass; it is a filter, not a simulation.

Produces a result that looks water-carved: channels running down slope and ridges, with fine rills branching off the walls of coarser ones. Each pixel is evaluated independently in one pass, and it runs on the GPU when one is available.

The idea follows Rune Skovbo Johansen's Advanced Terrain Erosion Filter (March 2026), re-implemented from its description.

Compared with a real simulation it lacks a continuous river network (a gully can end mid-slope), sediment deposition, and any dependence on upstream flow: gully depth depends only on local slope. For those you need flow accumulation, which is a different and much slower node.

The output overwrites the input height layer (so Height to Normal can follow without changes), and an extra erosion layer in [-1, 1] is written (ridges above 0, gullies below 0) for texture layering.

With tile on the result is seamless. With it off, origin_x/origin_y give the world position of the image's lower-left corner so tiles generated separately line up without seams.

Inputs

Outputs

Parameters

Erosion

Fade

Tiling

COP Flow Accumulation (PCG)#

PCG_COPFlowAccumulation · category PCG/cop

Computes how much upstream area drains through each pixel of a height field, and derives river, lake and flow direction layers from it.

First the height field is pit-filled with Priority-Flood plus an epsilon: depressions become lakes and every pixel is guaranteed a lower neighbour, so water always reaches an outlet (by default the four image edges; with tile the single lowest point; a base layer restricts outlets to its marked pixels). Then water is passed downstream by one of three methods: D8 (steepest neighbour; rivers are one pixel wide lines at 0 and 45 degrees), Rho8 (randomized D8, unbiased in average direction, seeded by rand_seed) or MFD (split among all lower neighbours by slope to the power of exponent, giving sheet flow on slopes). Inside a filled lake the water follows the drowned valley: the flat lake surface only carries the tiny epsilon slope toward the spill point, which would draw ruler-straight lines and hatching, so lake pixels drain along the lowest original terrain under the water to the lake's exit.

Output layers: flow is the drainage area (in world units squared; resolution independent in channels), river is a river-network mask with a logarithmic soft transition around river_area, lake is the fill depth and flow_dir is the downstream direction (u, v). An empty layer name disables that output. A rain layer, if given, scales rainfall per pixel (e.g. more on windward slopes).

Water is conserved: the total leaving through the outlets equals the total rainfall, and the report states it. The pit filling is a sequential priority queue and runs on the CPU only (about 3 s for 1024x1024).

Inputs

Outputs

Parameters

Flow

River

Output

COP Height to AO (PCG)#

PCG_COPHeightToAO · category PCG/cop · Houdini: Height to Ambient Occlusion (COP)

Computes ambient occlusion from a height field, where 1 is unoccluded and 0 is fully dark.

Horizon-based AO: from each pixel, directions rays are marched with steps samples out to radius pixels and the largest elevation angle above the pixel's tangent plane is found, converted to an occlusion and averaged over directions.

Elevation is measured against the tangent plane, not the horizontal. Measured against the horizontal, a whole slope would be occluded looking uphill, although an infinite slope has no occlusion physically. So any plane, however steep, gives exactly 1; convex shapes (peaks) give exactly 1; concave places (pits, gullies) are below 1 and darker with stronger curvature. Scaling height and world size together does not change the result, since only angles matter.

Cost is directions x steps full-image operations (64 by default). With tile off, samples outside the image do not contribute, so no dark rim appears along downhill edges.

Inputs

Outputs

Parameters

Height

Quality

COP Height to Caustics (PCG)#

PCG_COPHeightToCaustics · category PCG/cop · Houdini: Height to Caustics (COP)

Simulates the light patterns a water surface focuses onto the bottom, from a height field used as the water surface.

The output is 1 under a calm surface and above 1 where light is focused. It uses photon tracing: every pixel emits supersample squared photons, which are refracted by the surface normal (with the given index of refraction), travel to a floor at depth, and are splatted bilinearly into the four pixels around the landing point. This is more robust than inverting a Jacobian, because focal lines are exactly where the Jacobian is zero and an analytic approach would divide by zero there.

Properties: a calm surface gives exactly 1; with tile on, energy is conserved (the sum of all pixels equals the pixel count); a bump in the surface acts as a converging lens (above 1 directly below) and a dent as a diverging lens (below 1). With an IOR of 1 the image is about 1 everywhere. For oblique light, the shift caused by a calm surface is subtracted, so the pattern stays aligned with the surface above it. There is no Fresnel term, no absorption, and light is refracted once only.

The node runs on the CPU only, so results are deterministic (accumulation order matters for the last digits).

Inputs

Outputs

Parameters

Height

Water

Light

Quality

COP Height to Normal (PCG)#

PCG_COPHeightToNormal · category PCG/cop · Houdini: Height to Normal (COP)

Converts a height layer into a tangent-space normal layer (signed, +Y up, OpenGL convention).

Computes N = normalize(-dh/dx, -dh/dy, 1) with derivatives in world units, written as a signed layer in [-1, 1] with +Y equal to +v. Use it to get a normal map from a grayscale height from a diffusion model or an albedo conversion. Follow it with COP Convert Normal (signed to packed) to export, or feed Control Image in normal mode for ControlNet.

Scale: height value times Strength is the world height and World Size is the world width of the whole image. The eight height-field nodes share this pair with the same defaults, so tuning it once keeps AO, shadow and caustics in the same world.

On a linear slope h = a*x + b*y every pixel, including the border ring, gets exactly normalize(-a, -b, 1). One-sided differences are used at the border, because a clamp-padded central difference gives only half the slope in the outermost ring and would leave seams along the edges of a sloped tile.

Only channel 0 of a multi-channel layer is used; run COP Luminance first for color images.

Inputs

Outputs

Parameters

Derivatives

COP Height to Shadow (PCG)#

PCG_COPHeightToShadow · category PCG/cop · Houdini: Height to Shadow (COP)

Casts sun shadows over a height field, optionally with soft edges.

The output is a mask where 1 means in shadow. Turn on invert to get 1 for lit areas, which can be multiplied straight onto a color.

For each pixel, samples are taken toward the light up to max_distance pixels; if any sample's elevation angle exceeds the sun elevation, the pixel is in shadow. For a wall of height H the shadow length is exactly H / tan(elevation) in world scale, and at 90 degrees elevation there is no shadow.

Softness models the sun as a disc by its angular radius (a first-order approximation, not an area-light integral).

Inputs

Outputs

Parameters

Height

Light

Quality

COP HeightField Clip (PCG)#

PCG_COPHFClip · category PCG/cop · Houdini: HeightField Clip (COP)

Clamps a height layer into a minimum/maximum range, optionally with a soft knee.

Equivalent of HeightField Clip. Heights are limited to [Min, Max] in the chosen mode, with softness giving a C1 continuous knee instead of a hard edge. A second layer <out>_clipped holds the amount that was changed. The height layer defaults to C, like the rest of the terrain nodes. An optional mask blends the clipped result back into the original height.

Inputs

Outputs

Parameters

COP HeightField Cutout by Object (PCG)#

PCG_COPHFCutoutByObject · category PCG/cop

Carves the terrain down to the bottom of a geometry, fills it up to its top, or both.

The height field lies in the xz plane, centered, with width world_size; world height is the layer value times strength. For every texel two vertical rays are shot (down and up) to find the top and bottom of the geometry in that column (the outermost two if several layers exist).

carve lowers the ground to the geometry's bottom where the geometry passes through the ground (geometry fully buried does not cut a hole). fill raises the ground to the geometry's top where the geometry rests on the ground (floating geometry does not pull the ground up). both carves then fills, so the geometry's solid part becomes the terrain. A layer <out>_cut marks the modified texels with 1, useful for texturing or scatter avoidance.

Inputs

Outputs

Parameters

COP HeightField from Depth (PCG)#

PCG_COPHeightfieldFromDepth · category PCG/cop

Turns a single image's depth into a top-down height field, so a picture of a landscape can feed the terrain chain.

Intended workflow: an AI image of a valley, depth estimated by MoGe or Depth Anything, flattened here into a height field, then used with erosion, river networks, splat maps and mesh conversion.

perspective (landscape photos, AI perspective images): either connect moge_geometry (the core MoGeInference output, recommended; it supplies camera-space points, metric scale and a sky mask, so nothing is guessed), or connect depth (relative inverse depth from Depth Anything and similar, which is only known up to scale and offset: z = 1/(d + shift) is a guess and the FOV must be entered by hand; wrong guesses bend the terrain rather than scaling it). The ground plane is fitted with weights proportional to area (z squared) and the camera pitch is solved automatically. Points are rasterized top-down, a cell takes the mean height of the points that land in it, and unseen cells (behind mountains, sparse distant areas) are filled by push-pull. The mask layer marks the cells that were really measured; the filled values are guesses.

top_down (satellite images, AI orthographic maps): the depth is used directly as height, normalized to Relief times World Size.

Connect the original image to image to also get an albedo layer (the color projected top-down; MoGe supplies its own). The world_size output can be wired to the world size of the height-field family so scales match. The height layer is C.

Inputs

Outputs

Parameters

Disparity

Top Down

Tips

• Prefer moge_geometry over a plain depth map for perspective images; a guessed depth bends the terrain.
• Perspective mode needs ground running into the distance under a horizon. A figure, a portrait or a flat-coloured drawing has no ground to fit: the sky lifts as a wall at the back and the subject as a spike.

COP HeightField Hydraulic Erosion (PCG)#

PCG_COPHydraulicErosion · category PCG/cop · Houdini: HeightField Erode (COP)

Erodes a height layer with simulated water droplets that carry and deposit sediment.

Droplets run downhill, pick up material where it is steep and fast, and drop it where the slope flattens, the water evaporates and the speed falls. Gullies, alluvial fans and flat basin floors grow this way. In the terrain chain this is the only node that actually transports sediment: the erosion filters only carve, thermal erosion only collapses to the angle of repose, and stream power only cuts.

The model is the droplet model of Beyer 2015, with parameter names following Sebastian Lague's implementation. A batch of droplets runs at the same time and their changes are scatter-added back. Because hundreds of droplets can join one channel in the same step, each cell is dug at most down to its lowest neighbour and built up at most slightly above its highest neighbour, so no pits or spikes form. Material beyond that limit stays on the droplet, and the books balance per droplet: the change in total terrain volume equals minus the material that left over the map edge (and any discarded sediment), as stated in report.

Output layers: the eroded height (Output Layer), net deposition (Deposit Layer, default debris, accumulated onto an existing layer of the same name, so thermal-erosion talus and alluvial deposit end up in one layer), optional net erosion, and wetness (water traffic above the background level, normalized to 0-1, useful as a river or gully mask). Leave a layer name empty to skip that output.

Height Scale and World Size give the world scale: height value times Height Scale is world height, and World Size is the world width of the whole image. Droplets per Pixel of 1 is roughly Lague's default amount.

Inputs

Outputs

Parameters

Erosion

Erosion › Droplet

Erosion › Brush

Output

Advanced

Compared with Houdini

Corresponds to HeightField Erode but implemented as a droplet (particle) model that transports sediment, not Houdini's solver. Parameter names follow the Lague implementation.

Tips

• Put it after thermal erosion: the debris layer then holds both talus and alluvial deposit, which the Splat Map node reads for sediment by default.
• Droplet paths are sensitive to rounding, so expect the same seed to look different on CPU and GPU.

COP HeightField Mask by Feature (PCG)#

PCG_COPMaskByFeature · category PCG/cop · Houdini: HeightField Mask by Feature (COP)

Builds a mask from terrain features: slope, direction, height, curvature and occlusion.

Each enabled criterion gives a 0-1 mask, and the enabled criteria are combined with Blend Mode (multiply by default, so all must hold). If no criterion is enabled the mask is all 1. Soft edges use smoothstep; a falloff of 0 gives a hard edge. Smooth Radius blurs the height first (world units) and all features are measured on the blurred height. Scale parameters (Height Scale, World Size) follow the same convention as the other height-layer nodes.

Typical uses: rock on slopes of 35 degrees or more, gravel in gullies, snow on north-facing slopes (a Goal Angle of 90 degrees means downhill points toward +v).

• Slope: angle in degrees between the surface and the horizontal.
• Direction: downhill direction within Angle Spread of the Goal Angle (0 degrees is +u, 90 degrees is +v). Flat ground has no direction and scores 0.
• Height: range in raw height values (Height Scale is not applied).
• Curvature: tangential curvature separates ridges from gullies without using elevation, which flips on high gullies and low ridges. The height is blurred by Blur Radius pixels first (pixel-level curvature is noise), then divided by a reference value: Reference Curvature if greater than 0 (per world unit; required for tiled generation), otherwise the 90th percentile of |curvature| of this image. Threshold 0 then splits ridges from gullies; higher values select only sharper features.
• Occlusion: 1 minus the height-to-AO result, so 0 is open and 1 is fully blocked.

Inputs

Outputs

Parameters

Slope

Direction

Height

Curvature

Occlusion

COP HeightField Mask by Object (PCG)#

PCG_COPHFMaskByObject · category PCG/cop

Projects a geometry vertically onto a height field and outputs a mask of where it covers, crosses, floats above or is buried below the ground.

Uses the same grid convention as HeightField Project: xz plane, centered, width world_size, world height equal to layer value times strength. Each texel's column is tested with rays from above and below to find the top and bottom of the geometry.

Modes: footprint is 1 wherever the geometry covers the column; intersect where the geometry passes through the ground (bottom at or below the ground and top at or above it); above where the geometry is entirely above the ground; below where it is entirely buried.

feather softens the mask outward by a world-space distance (exact distance with a smoothstep). invert flips the mask.

Inputs

Outputs

Parameters

COP HeightField Project (PCG)#

PCG_COPHFProject · category PCG/cop · Houdini: HeightField Project (COP), HeightField Transform 3D (COP)

Projects geometry down onto a height field, or, with no geometry connected, transforms the height field in 3D and projects it back.

Covers HeightField Project and HeightField Transform 3D. With geo connected, a ray is cast straight down from above each texel; the height of the hit, divided by strength, is combined into the layer according to mode. With no geometry, the height field itself is turned into a mesh, transformed with translate, rotate (Euler XYZ, degrees) and scale about its center, and projected back onto the same grid. The mode is then always Replace, so tilting, lifting or rotating a terrain is a true 3D transform and not an image-space warp.

project chooses which surface a ray takes: the highest hit, or the lowest (Minimum Height). If max_height is above 0, only geometry whose height value lies within plus/minus that value is projected. mask and mask_layer blend the result with the original height. projection_only outputs just the projected heights without compositing, and hitmask_layer writes a mask of the texels that were hit. The second output is a report with the number of hit texels.

The grid convention is the one of HeightField to Mesh: xz plane, centered, width world_size.

Inputs

Outputs

Parameters

Transform 3D

COP HeightField Splat Map (PCG)#

PCG_COPSplatMap · category PCG/cop

Derives a set of grass, sediment, rock, snow and water material masks that sum to one from a terrain.

Produces masks that always add up to exactly 1 per pixel, for engine terrain layers, regional prompts or a segmentation ControlNet (use the id layer).

The layers are composited in order, later ones covering earlier ones: water over snow over rock over sediment over grass. Rock is steep slope. Snow is above the snow line and not too steep (steep faces cannot hold snow). Sediment comes from the debris layer (a thermal erosion output) or, without one, from low flat areas. Water comes from lake / river layers (flow accumulation outputs).

Height is normalized per image by default (a snow line of 0.75 is the top quarter); use Absolute when tiled generation must line up. Besides the masks, <prefix>_id holds the index of the dominant material and <prefix>_rgba packs rock, snow, sediment and water (grass is implied). The second output is a text report.

Inputs

Outputs

Parameters

Rock

Snow

Sediment

Water

COP HeightField Stream Power Erosion (PCG)#

PCG_COPStreamPower · category PCG/cop

Erodes a height layer by simulating the stream power law with an implicit solver.

Solves dh/dt = U - K * A^m * S (uplift minus erodibility times drainage area to the m times slope) in the FastScape manner. Unlike an erosion filter, this is a simulation that recomputes flow routing every step, so large rivers cut deep while hillslopes barely change, and a continuous, hierarchical river network that reaches the outlets develops.

Two uses: with Uplift 0, carve valleys into existing terrain (tens of iterations); with Uplift above 0, build mountains from noise as uplift and erosion balance (hundreds of iterations). The Uplift Layer multiplies uplift (raise only the middle for a mountain range). Slope Diffusion rounds hillslopes and dulls ridges.

The implicit scheme is stable for any step size and creates no new pits (depressions are filled once at the start and lakes are filled as sediment). Outlets are fixed base level. D8 routing pulls rivers into straight lines at 0 and 45 degrees; Rho8 randomly picks diagonals each step, which is unbiased on average (reproducible with a fixed seed). Large flat areas after lake filling can still show straight lines, caused by the epsilon slope toward the nearest outlet, regardless of routing. CPU only, around 0.2 s per step at 512x512.

The second output is a text report. The Flow Layer receives the drainage area of the last step.

Inputs

Outputs

Parameters

Erosion

Uplift

Boundary

COP HeightField Terrace (PCG)#

PCG_COPTerrace · category PCG/cop · Houdini: HeightField Terrace (COP)

Turns a height layer into terraces with flat treads and steep risers.

Works directly on the height values. Heights are divided into steps; the relative position f inside each step (0-1) is passed through the power function f^p with p = 1 / (1 - Sharpness). At Sharpness 0 the function is the identity and the height is unchanged; towards 1 the treads become flat and the risers steep, and at 1 the result is a pure staircase.

The result is monotonic (high ground never ends up lower than low ground), the step boundaries at Offset + k * Step do not move, and the node only cuts, never fills (output is not higher than the input).

In Number of Terraces mode the step size is (Max Height - Min Height) / Terraces and terracing is limited to that range; in Step Size mode it applies to all heights unless Limit Range is on. Heights outside the range are left untouched. A mask layer (and/or the Mask value) blends between the original and the terraced height, for example to terrace only the steep slopes.

Inputs

Outputs

Parameters

Compared with Houdini

Follows HeightField Terrace's Step Size / Number of Terraces methods, Limit Range, Random Step and Mask. Sharpness is an addition of this plugin; Houdini does not document the riser profile. At the ends of the limited range there can be a step-like jump when the step size does not divide the range or Offset is non-zero; no extra transition is applied.

Tips

• Put a slope mask (for example Mask by Feature) in front and connect it as the mask layer to terrace only steep areas.

COP HeightField Thermal Erosion (PCG)#

PCG_COPThermalErosion · category PCG/cop · Houdini: HeightField Slump (COP)

Collapses slopes steeper than the angle of repose, moving material downhill and piling it up at the foot.

Thermal erosion (slumping): wherever the terrain is steeper than the talus angle, loose material slides downhill until the slope relaxes to that angle. It is different from the Erosion Filter node, which carves channels; this one flattens over-steep slopes and builds talus fans at their base. A common order is Erosion Filter followed by Thermal Erosion, to collapse the too-steep gully walls the filter produced.

Mass is conserved (the total height does not change). Terrain that is everywhere gentler than the talus angle is returned bit-identical, and a tall column collapses into a cone whose slope converges to the angle of repose. The cost is Iterations times the number of neighbours in full-image passes. With Compute on Auto, large images run on the GPU in float32 when one is available; the result is returned on the original backend.

The Debris Source menu selects between two models. With Whole Height the entire height value can slide (the classic thermal behaviour) and the debris layer receives the net deposit. With Debris Layer or Constant Depth (Houdini HeightField Slump semantics) the height is fixed bedrock and only the debris layer slides on top of it; when debris is slid away the bedrock is exposed, and the debris layer then holds the remaining debris thickness. In Granular mode the amount moved per step and cell is randomised.

A hardness layer marks bedrock that never moves.

Inputs

Outputs

Parameters

Compared with Houdini

Corresponds to HeightField Slump. The Debris Layer and Constant Depth sources follow its semantics (fixed bedrock, sliding debris). Whole Height is the plugin's original thermal behaviour.

Tips

• Run it after the Erosion Filter to relax steep gully walls.
• Use the debris layer as a mask to paint scree textures.

COP Mono to HeightField (PCG)#

PCG_COPMonoToHeightField · category PCG/cop · Houdini: Mono to HeightField (COP)

Converts a single-channel layer into a height layer by scaling and offsetting its values.

The height is value * Height Scale + Height Offset (scale first, then offset, so Offset is in final height units). Only the first channel of the layer is used. Layers have no type metadata in this plugin, so the result is recognised as a height field by its layer name; the default output name is height.

Inputs

Outputs

Parameters

Compared with Houdini

Houdini also flags the layer's Type Info as height. Layers here carry no such flag; height layers are identified by naming convention.

COP Normal to Height (PCG)#

PCG_COPNormalToHeight · category PCG/cop · Houdini: Normal to Height (COP)

Reconstructs a height layer from a normal map; the inverse of Height to Normal.

The output has zero mean. With the same Height Scale and World Size used for the forward conversion, the recovered height differs from the original only by a constant. Typical use: you only have a normal map (scan, bake, AI-generated) and need a height for displacement, parallax or terrain.

Two integrators, with a real trade-off:

• Spectral (Frankot-Chellappa): robust for inconsistent normal maps (AI or hand-painted maps that do not correspond to any real surface), but it attenuates fine detail: undulations with a 16-pixel period come back at 97.5%, a 4-pixel period at 64%.
• Exact: a pixel-exact inverse of Height to Normal (central differences, tiled), but inconsistent input produces checkerboard patterns at high frequency. Use it when you convert back and forth inside your own chain.

With Tileable off, the edges are extended by mirroring (zero slope at the border), so the few pixels near the edge are approximate, and Exact is then worse than Spectral (the mirror seams are inconsistent and the exact method amplifies them). Use Exact with tiling and Spectral without.

Normals with z at or below 0.01 are clamped to avoid exploding slopes; report states how many were clamped.

Inputs

Outputs

Parameters

Integration

COP Slope & Aspect (PCG)#

PCG_COPSlope · category PCG/cop · Houdini: Slope Direction (COP)

Computes slope, aspect and downhill direction from a height layer.

Writes up to three layers; leaving a layer name empty skips that layer. Slope is available in degrees (0 to 90), as a tangent (the gradient magnitude) or normalized to 0 to 1. Aspect is the downhill direction in degrees, with 0 pointing along +U and 90 along +V, and is 0 on flat areas. The downhill direction layer holds the unit vector (u, v) pointing downhill; wiring it into COP Distort drags pixels along the slope.

Slope and aspect are exact per pixel on inclined planes, and the derivatives use quadratic extrapolation at the borders, so even the boundary is exact on quadratic surfaces. The scale parameters match the other height-field nodes.

Inputs

Outputs

Parameters

COP Strata (PCG)#

PCG_COPStrata · category PCG/cop · Houdini: HeightField Strata (COP)

Adds tilted rock strata to a height layer as terraced layers with random hardness.

The layer plane is height + Tilt * (u, v) + noise. Each stratum gets a random hardness: hard layers have flat tops and steep steps. The result is mixed back by Strength. With Tilt, noise and randomness all 0 this is a plain terrace. A layer index is also written as <Output Layer>_id. Strata Offset shifts the layer boundaries, a Mask Layer multiplies Strength, and Output Strata Only outputs just the strata displacement (adding it to the height equals Strength 1).

Inputs

Outputs

Parameters

Compared with Houdini

Houdini's Strata lays 1D noise along tilted planes and combines it with the height by a Blend Mode. This node implements a different model, tilted terraces.