PlanetGen troubleshooting
Grass or foliage floats above the ground
Section titled “Grass or foliage floats above the ground”Cause: a noise layer’s Frequency is finer than your chunk vertices can represent. A chunk samples noise only at its vertices, spaced Tile Size / (Resolution − 1) apart. Detail finer than that becomes per-vertex jitter, and grass and trees, which are placed by interpolating those vertices, end up off the rendered triangles.
Fix:
- Check the read-only Scale Check on each noise layer. It reads
OK,MARGINALorTOO FINEfor your current settings. Offending layers are also named in the log at generation time, along with the frequency ceiling. - Lower the offending layer’s Frequency, or raise Resolution / lower Tile Size if you really want finer terrain.
Aim for at least 4 vertex samples per noise wavelength, which means Frequency ≤ 1 / (4 × vertex spacing). For example, with a 1 km tile at resolution 64 the vertex spacing is about 15.9 m, so the practical ceiling is roughly 0.00015.
The editor runs out of memory on a large planet
Section titled “The editor runs out of memory on a large planet”Symptom: Ran out of memory … The paging file is too small.
Cause: that message is about the Windows commit limit (RAM + page file), not physical RAM. A planet’s chunk pool is 6 × ChunksPerFace², where ChunksPerFace = min(PlanetRadius × π/2 ÷ TileSize, MaxChunksPerFace):
| Planet | Chunks per face | Chunks | Approx. chunk memory |
|---|---|---|---|
| 6 km radius, 1 km tiles (default) | 9 | 486 | ~0.2 GB |
| 15 km, 1 km tiles | 24 | 3,456 | ~1.5 GB |
| 50 km, 1 km tiles | 32 (capped) | 6,144 | ~2.5 GB |
| 50 km, cap raised to 79 | 79 | 37,446 | ~15 GB |
(Resolution 64 with collision; memory scales with Resolution².)
Fix: use any of these:
- Lower Max Chunks Per Face (for example 16 gives 1,536 chunks per planet).
- Raise Tile Size (fewer chunks) or lower Resolution (cheaper chunks).
- Set a fixed Windows page file, for example 32 to 64 GB.
Packaged games use far less memory than the editor, since there is no shader compilation, DDC or editor baseline. Ring worlds stream a window around the player, so a large ring radius does not grow memory the same way.
Volumetric clouds are missing on UE 5.4 or 5.5
Section titled “Volumetric clouds are missing on UE 5.4 or 5.5”This was a bug in versions before 1.9: a UE 5.6+ cloud fix was also being applied on 5.4 and 5.5, where it blanked volumetric clouds. Update to PlanetGen 1.9 or later.
Cloud edges look blocky on UE 5.6+
Section titled “Cloud edges look blocky on UE 5.6+”UE 5.6 changed how the reduced-resolution cloud render target is upsampled, leaving a blocky, sky-coloured fringe along high-contrast edges such as foliage against cloud. Make sure High Quality Cloud Reconstruction (Planet | Atmosphere) is on (the default). Turn it off only if your project manages the r.VolumetricRenderTarget console variables itself.
The night side is too bright, or clouds glow at night
Section titled “The night side is too bright, or clouds glow at night”- Use a fixed exposure. Auto-exposure reacts to the dark hemisphere and re-brightens it.
- Custom materials need the day/night terminator. A directional light is not blocked by the planet itself, so without a terminator, sun-facing slopes and foliage stay lit on the night side.
M_Planetalready has it; for your own terrain or foliage materials, useMF_DayFactorLocal. - Distant planets lit from the wrong side? Take
PlanetCenterfrom the material’s own vector parameter (whichMF_DayFactorLocaldoes), not fromMPC_Planet. The collection can hold only one planet’s centre.SunDirectionshould still come fromMPC_Planet.
The ocean looks blocky, banded or has a jagged foam line
Section titled “The ocean looks blocky, banded or has a jagged foam line”The depth colour, foam and clear shallows are stored per water vertex, so they need Adaptive Water Tessellation on. If you need it off, switch the water material to M_SimplePlanetWater.
The editor freezes when I change Planet Radius
Section titled “The editor freezes when I change Planet Radius”On very large planets, the live water rebuild is heavy. Turn off Live Water Update (editor): the water will then rebuild only when you click Preview. This affects the editor only and never packaged-game frame rate.
My slope mask has seams between chunks
Section titled “My slope mask has seams between chunks”In custom materials, don’t use ObjectPosition, which is each chunk’s own origin. Use dot(VertexNormalWS, normalize(AbsoluteWorldPosition − PlanetCenter)) with the PlanetCenter parameter that PlanetGen sets automatically.
Spawner actors don’t appear
Section titled “Spawner actors don’t appear”- Tick Enable Spawner on the planet (it is off by default) and add your assets to Spawner Assets.
- The spawner runs in Play / PIE only, not in the editor preview.
- Respect Exclusion Volumes (on by default) skips cells covered by exclusion volumes.
- Check the asset’s Biome, slope and height filters against where you are standing.
Spawned characters fall through the terrain
Section titled “Spawned characters fall through the terrain”Their terrain collision has not finished cooking. Turn on Apply Terrain Load Delay on the spawner asset, and adjust Spawner Terrain Load Delay (seconds) on the planet.
An exclusion volume has no effect
Section titled “An exclusion volume has no effect”- Check Enable Exclusion Volumes on the planet (on by default).
- Click Align To Planet after moving the volume so its pad lies flat against the surface.
- Where volumes overlap, the strongest blend wins.
Tiered chunk LOD shows lighting seams
Section titled “Tiered chunk LOD shows lighting seams”Tiered Chunk Resolution is experimental and off by default. Position cracks between tiers are stitched, but cross-tier lighting seams are still being refined. Turn it off if the seams are visible in your scene.
The hyperdrive flies through terrain
Section titled “The hyperdrive flies through terrain”FastFlyTo has no collision on the way, so aim at a point above the ground. It is not a predicted move either: call it in single-player or on the authority.