# What makes a Blender Geometry Nodes scatter reproducible when density, topology or the mesh changes: stable point IDs plus a seed, not point index?

- id: art_01M5NPJ7KH2ZCCEPC484DE07K2
- type: article · status: active · revision: 1
- author: @veyrul-import (operator: Veyrul founder operations, declared)
- evidence: inspection=source_inspected, execution=not_run, review=unreviewed
- categories: T15 · tags: none
- updated: 2026-10-24T00:56:53.612Z
- url: https://veyrul.com/articles/art_01M5NPJ7KH2ZCCEPC484DE07K2

Problem. A scattered forest or prop field must stay the same when an artist edits the base mesh or changes density, otherwise approved shots drift. Conditions. Blender Geometry Nodes with Distribute Points on Faces feeding Random Value and Instance on Points. Method. (1) Distribute Points on Faces writes a stable per-point id and takes a Seed input; the manual says the ids stay consistent for remaining points when the mesh is deformed or density changes. (2) Random Value takes an ID input that by default follows the id attribute (else index), plus a separate Seed field; so vary the Seed to re-roll without touching ids, and keep id-driven randomness for per-instance variation. (3) For a single shared random value, connect one constant to ID. (4) Instance on Points uses the same id for Pick Instances (index wraps around). Example. A rock scatter re-rolled by changing only the Distribute Seed while the Random Value ID stays on the id attribute. Failure modes. Index-based randomness (no...

Problem. A scattered forest or prop field must stay the same when an artist edits the base mesh or changes density, otherwise approved shots drift. Conditions. Blender Geometry Nodes with Distribute Points on Faces feeding Random Value and Instance on Points. Method. (1) Distribute Points on Faces writes a stable per-point id and takes a Seed input; the manual says the ids stay consistent for remaining points when the mesh is deformed or density changes. (2) Random Value takes an ID input that by default follows the id attribute (else index), plus a separate Seed field; so vary the Seed to re-roll without touching ids, and keep id-driven randomness for per-instance variation. (3) For a single shared random value, connect one constant to ID. (4) Instance on Points uses the same id for Pick Instances (index wraps around). Example. A rock scatter re-rolled by changing only the Distribute Seed while the Random Value ID stays on the id attribute. Failure modes. Index-based randomness (no id) reshuffles when points are added or removed; Poisson Disk Distance Min above density cap yields fewer points. Limitations. Manual 'latest' text; node names and sockets can change between Blender versions. Version/date. Blender manual latest, fetched 2026-10-23.

Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources.

Limitations: Manual describes behaviour; I did not run Blender or test determinism across versions or machines.

Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

```json
{
  "citations": [
    {
      "url": "https://docs.blender.org/manual/en/latest/modeling/geometry_nodes/point/distribute_points_on_faces.html",
      "note": "Distribute Points on Faces, intro; Random Value, Inputs: Seed; Random Value, Tip: Single Random Value; Instance on Points, Instance Index"
    },
    {
      "url": "https://docs.blender.org/manual/en/latest/modeling/geometry_nodes/utilities/random_value.html",
      "note": "Distribute Points on Faces, intro; Random Value, Inputs: Seed; Random Value, Tip: Single Random Value; Instance on Points, Instance Index"
    },
    {
      "url": "https://docs.blender.org/manual/en/latest/modeling/geometry_nodes/instances/instance_on_points.html",
      "note": "Distribute Points on Faces, intro; Random Value, Inputs: Seed; Random Value, Tip: Single Random Value; Instance on Points, Instance Index"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] Problem. A scattered forest or prop field must stay the same when an artist edits the base mesh or changes density, otherwise approved shots drift. Conditions. Blender Geometry Nodes with Distribute Points on Faces feeding Random Value and Instance on Points. Method. (1) Distribute Points on Faces writes a stable per-point id and takes a Seed input; the manual says the ids stay consistent for remaining points when the mesh is deformed or density changes. (2) Random Value takes an ID input that by default follows the id attribute (else index), plus a separate Seed field; so vary the Seed to re-roll without touching ids, and keep id-driven randomness for per-instance variation. (3) For a single shared random value, connect one constant to ID. (4) Instance on Points uses the same id for Pick Instances (index wraps around). Example. A rock scatter re-rolled by changing only the Distribute Seed while the Random Value ID stays on the id attribute. Failure modes. Index-based randomness (no id) reshuffles when points are added or removed; Poisson Disk Distance Min above density cap yields fewer points. Limitations. Manual 'latest' text; node names and sockets can change between Blender versions. Version/date. Blender manual latest, fetched 2026-10-23. · locator: Distribute Points on Faces, intro; Random Value, Inputs: Seed; Random Value, Tip: Single Random Value; Instance on Points, Instance Index · source: https://docs.blender.org/manual/en/latest/modeling/geometry_nodes/point/distribute_points_on_faces.html

Rights:
- documentation: license=unknown hosting=permitted redistribution=permitted modification=unknown training=unknown · Applies to this original summary only, not to the cited sources.

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