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Mycelium Documentation

Mycelium is a Grasshopper plugin for generative urban massing in Rhino 8. Feed it a closed parcel boundary and it returns a complete city block: subdivided parcels, streets, building masses across six typologies, parks, trees, terrain, and a full set of development and morphology metrics.

Sample massing outputs

Install

In Rhino 8, run _PackageManager, search for mycelium, install, and restart. The components appear in Grasshopper under the Mycelium tab.

Manual install, pre-release builds, and building from source are covered on the download page.

Rhino 8 only

Mycelium targets .NET 7 and relies on assemblies that only Rhino 8 supplies. It does not load in Rhino 7.

Where Things Are

Components are organized into five panels. The component reference carries the full toolbar and a card per component; each panel page below carries its own.

Panel What lives there
Massing The generator itself — parcel in, city block out
Building Types One config component per typology
Vegetation Tree density, size, courtyard placement
Site Procedural terrain
Utilities Example definitions synced from GitHub

How the Pieces Fit

Boundary curve ─┐
                │
Config comps ───┼──▶  Massing Generator  ──▶ Footprints, Masses, Streets,
                │                             Parks, Courtyards, Trees, Parcels
Tree Config ────┘                        ──▶ Metrics, MorphologyMetrics
                                         ──▶ CaseManifest (JSON provenance)
  1. Subdivision — recursive binary space partitioning splits the parcel into building blocks separated by streets. The street-network family is chosen from the component's right-click menu or driven by the StreetNetwork input.
  2. Typologies — each block receives a randomly selected building type from the configurations you wired in: courtyard, linear, point, L-shape, U-shape, or tower.
  3. Open space — NumParks blocks become parks and are populated with procedural trees; courtyards can receive trees too.
  4. Metrics & provenance — development metrics, morphology indicators, and a schema-versioned JSON case manifest for every alternative.

Everything is driven by the Seed input, so alternatives are reproducible.

Algorithm overview

Getting Help

When reporting a geometry problem, include the CaseManifest JSON — it pins down the exact inputs, seed, and plugin version that produced the result.