oce-bim-takeoff

name	oce-bim-takeoff
description	CAD/BIM takeoff in OpenConstructionERP: upload Revit/IFC/DWG/DGN models, browse elements, bulk-link them to BOQ lines, measure DWG drawings and PDF plans, and push quantities into the estimate. Use for any model-based quantification workflow.

BIM & CAD Takeoff in OpenConstructionERP

Supported formats

Format	In	Out
RVT (Revit)	upload	canonical JSON, GLB, thumbnails
IFC	upload (no IfcOpenShell required)	JSON/GLB
DWG	upload + layer browse	measured entities
DGN	upload	JSON/GLB
PDF	plan upload	vector/room measurements, dimension text (OCR optional)
LAS/LAZ/COPC	point-cloud viewer	decimated THREE.Points buffers

Conversions run in-process via the bundled DDC converters; artifacts persist under data/bim/{project_id}/{model_id}/.

Workflow

1. Upload the model to a project (POST /api/v1/bim/...).
2. Browse elements (walls, slabs, doors…) with quantities computed from the model geometry (area / volume / length).
3. Bulk-link to BOQ — select 100 wall elements → one BOQ line with aggregated area; the element↔cost links are stored, so changes flow both ways.
4. Measure drawings — DWG layers (vector entities) and PDF plans (rooms/walls) measure in place; results push into BOQ rows.
5. Verify — the linked quantities appear in the BOQ grid; the estimate quality score updates.

Matching elements to cost items

• POST /api/v1/costs/suggest-for-element ranks cost items for a BIM element body (type, material, dimensions, classification).
• Matches carry confidence/certainty badges — review low-certainty picks before binding.

4D/5D hand-off

• Element quantities → BOQ (5D cost model).
• Task links → schedule (4D): each task can carry linked BIM elements for visual sequencing.

Honest limitations

• The platform does not run FX/PPP conversions at takeoff time — markets are pre-priced upstream.
• RVT/IFC extraction uses the bundled converters; exotic family data may need the converter repo (cad2data-Revit-IFC-DWG-DGN-pipeline).
• Point-cloud ingestion supports LAS/LAZ/COPC (E57 via the optional extra).

Best practices

1. Link elements in bulk, not one-by-one — the platform aggregates per BOQ line.
2. Keep original CAD only when you need re-conversion (keep_original_cad); artifacts are always retained.
3. Verify takeoff quantities against the model's own dimensions, then re-run BOQ validation.