BIM pipeline¶

bim-svc is active from M4 (validation + viewer) and M5 (metadata extraction + zoning compare). Large IFC files never enter the FastAPI request path; uploads are direct-to-GCS, and all validation, extraction, and tiling run on dedicated GKE workers.

Pipeline stages¶

flowchart TD
  U["① Upload<br/>PSP PUT IFC direct to GCS via signed URL"]
  V["② Integrity & format validation<br/>IfcOpenShell<br/>· IFC2x3 / IFC4 schema<br/>· file hash + corruption check<br/>· authoring-tool metadata<br/>· naming convention"]
  M["③ Metadata extraction (M5)<br/>· building height, storey count, GFA<br/>· site / lot reference<br/>· georef / coordinate system"]
  T["④ Tile generation<br/>IFC → XKT tiles (async worker)<br/>cache per submission + revision"]
  Z["⑤ Zoning overlay (M5)<br/>fetch zoning envelope from Masterplan GIS<br/>compute exceedance (height / setback / plot ratio)"]
  VWR["⑥ Viewer<br/>xeokit in SPA<br/>pan · zoom · rotate · section · measure<br/>floor toggle · lot boundary · zoning envelope<br/>visual compliance checklist (M4)<br/>federated view (M5)"]

  U --> V
  V -->|ok| M
  V -->|ok| T
  M --> Z
  V -->|failed| FAIL["bim.validation.completed<br/>reasons[]"]
  V --> EV1[bim.validation.completed]
  M --> EV2[bim.metadata.extracted]
  Z --> EV3[bim.zoning.exceedance.flagged]
  T --> VWR

Why uploads bypass FastAPI¶

Large IFC files would pin FastAPI worker threads and dominate bandwidth. The upload handshake:

sequenceDiagram
  autonumber
  participant PSP
  participant SPA
  participant SUB as submission-svc
  participant GCS as GCS<br/>siss-uploads
  participant BIM as bim-svc (worker)

  PSP->>SPA: pick IFC file
  SPA->>SUB: POST /submissions/{id}/files/request-upload<br/>(filename, content_type, size)
  SUB-->>SPA: V4-signed PUT URL (scoped)
  SPA->>GCS: PUT <large IFC>
  GCS-->>SPA: 200 OK
  SPA->>SUB: POST /submissions/{id}/files/confirm
  SUB->>GCS: read metadata + hash
  SUB-->>BIM: submission.files.attached
  BIM->>GCS: download IFC
  BIM->>BIM: validate · extract · tile
  BIM-->>SUB: bim.validation.completed<br/>bim.metadata.extracted

Viewer capabilities¶

The xeokit-based viewer in the SPA supports —

• pan / zoom / rotate / section cut
• measure height and distance
• toggle floors and auxiliary layers
• overlay lot boundary (GeoJSON) and zoning envelope
• visual compliance confirmation checklist (M4)
• federated view with neighbouring approved models (M5)

Tiles stream on demand from siss-processed via short-lived signed URLs.

Scale and accuracy gates¶

• Worker pool. BIM validation, extraction, and tiling run on a dedicated GKE node pool; FastAPI is never in the critical path.
• Accuracy golden-set. M5 extraction is measured against a golden set of reference IFC files. The M5 milestone gate is ≥ 90% height accuracy within tolerance. See Testing for the AI eval harness.