OpenRebar

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OpenRebar turns a required-area map of a flat reinforced-concrete slab into bars, anchorage, laps, a schedule, a cutting plan, and an IFC file. The map arrives as a DXF isoline drawing, a calibrated PNG, or a numeric field. The core is deterministic. A language model does not place bars and does not set a pass/fail flag.

The libraries build for .NET 8 and .NET 10. The CLI is .NET 10. The Revit add-in is two builds, chosen by the process runtime: RevitNet8 while Revit is still on .NET 8, and RevitNet10 on .NET 10. Engineering rules are tested without Revit.

What this is not. It is not a finite-element solver, not a trained segmenter, and not a crack-width or deflection calculator. It does not place bent bars in Revit. It does not claim a steel saving. The optional ml/ service ships with an empty model manifest and stays offline.

Status

Counted regression, the five commands under Quick start: 453/453 tests passing.

Surface	Now
Report	schemaVersion 2.1.0, contract OpenRebar.reinforcement.report.v2
Norms	SP 63.13330.2018, profile ru.sp63.2018, tables ru.sp63.2018.tables.v3
Area check	Cell grid. Passed only at zero deficit. A hard clash does not replace that gate
checks	providedArea follows the area check. Crack width and deflection stay NotEvaluated
Cutting	Column generation (HiGHS) with a recorded provenance. Waste percent and estimatedCost (null when the catalogue has no price)
IFC	IFC4. One bar type per diameter and steel class, a swept disk of radius d/2, a placement on the axis. CI checks those entity names
Revit	Straight bars only. A hook, L, or U is an error, not a straight line

The worked example examples/dxf/simple-slab exits 2. Edges are free, the required area runs to the edge, and a hook is not credited. That failure is the regression, not a bug in the snapshot.

Stage

The examples are synthetic fixtures. They exercise the pipeline and the regression. They are not a measured pilot in a design office, and they are not a certificate.

Shown on those fixtures:

• a free-edge slab whose area check fails, and a supported slab whose area check passes
• a report that rejects unknown fields
• an IFC file whose bar type, body, and placement the CI check can see

Not shown here:

• a profile signed by an organisation, or a scan of every cited clause
• a trained PNG segmenter
• bent bars placed in a live Revit model
• an IFC file opened again by another program
• a saving of steel or money

If this page and the tests disagree, the tests win. The rule for publishing a number is docs/VALIDATION_BASELINE.md.

Where it sits

Role	Program	Boundary
Required area	A calculation program writes As,req	OpenRebar does not solve the slab
Layout and area check	OpenRebar	Does not accept the documentation pack
Pack check	AeroBIM	Reads a model, a sheet, a schedule, and text. Sets its own pack flag. Does not design the bars

Scheduling engines, marketplaces, and research notes under the same GitHub account are other products.

Pipeline

1. Read the isoline file. A DXF entity that is not a zone is counted, not dropped. A PNG is measured from its header before decode.
2. Classify zones and record decomposition coverage.
3. Place bars. Spacing on a face is measured on the combined layer. Anchorage and lap lengths come from the versioned tables. Hook credit is 0. The default hook tail is 0.
4. Cut stock. A bar that cannot be bought or lapped is a critical error.
5. Check provided area against required area and write checks.
6. Write *.result.json, *.schedule.csv, *.aerobim.json, and *.reinforcement.ifc.

SOTA 2026, stated as a gap

The comparison lives in docs/SOTA_2026.md. The short form:

Topic	In this repository	Not in this repository
Area certificate	Per-cell margin and a deficit polygon	A claim that the layout is optimal
Provenance	Profile id, table version, optimizer id, parameter source	A norm typed from memory
Cutting	Column generation plus a recorded waste and purchase cost	A measured saving in percent or money
IFC	IFC4 bar type, swept disk, placement, IDS entity names in CI	IFC 4.3 lap-splice encoding, a viewer round-trip
Image segmentation	Exact RGB match. The U-Net path has no checkpoint	SAM2, DINOv2, a published mIoU
Layout search	Zone rules and a spacing check	GNN, reinforcement learning, a physics-informed net
Serviceability	NotEvaluated for crack width and deflection	A PINN or a code check of those limits

Quick start

Requirements: .NET SDK 8 and 10, Python 3.11 for the CI scripts and the optional ML lane.

dotnet restore OpenRebar.sln --locked-mode -p:EnableWindowsTargeting=true -p:Platform=x64
dotnet build OpenRebar.sln --no-restore --configuration Release -p:EnableWindowsTargeting=true -p:Platform=x64
dotnet format OpenRebar.sln --verify-no-changes --no-restore
dotnet test tests/OpenRebar.Domain.Tests/OpenRebar.Domain.Tests.csproj --no-build --configuration Release -f net8.0
dotnet test tests/OpenRebar.Infrastructure.Tests/OpenRebar.Infrastructure.Tests.csproj --no-build --configuration Release -f net8.0
dotnet test tests/OpenRebar.TestCorpus/OpenRebar.TestCorpus.csproj --no-build --configuration Release -f net8.0
dotnet test tests/OpenRebar.Application.Tests/OpenRebar.Application.Tests.csproj --no-build --configuration Release -f net8.0
dotnet test tests/OpenRebar.Cli.Tests/OpenRebar.Cli.Tests.csproj --no-build --configuration Release -f net10.0
python tools/ci/verify_readme_regression_claim.py

One slab:

dotnet run --project src/OpenRebar.Cli --configuration Release -- examples/dxf/simple-slab/input.dxf --thickness 220 --cover 30 --slab-width 6000 --slab-height 4000 --layer BottomX

Exit 2 means the area check failed and the files were still written. Exit 1 is an input or IO failure. Exit 3 is a critical detailing error.

Useful flags: --legend, --catalog, --ml-url, --slab-width, --slab-height, --thickness, --cover.

Outputs

File	Role
*.result.json	Canonical report. Unknown properties are rejected
*.schedule.csv	Positions and mass. Spreadsheet-safe quoting
*.aerobim.json	Short summary for a downstream checker
*.reinforcement.ifc	IFC4 bars

The report keeps the normative profile, the table version, optimizer provenance, kerf-aware wastePercent, and estimatedCost. A new top-level field requires a schema bump. checks[].status is Passed, Failed, or NotEvaluated.

Layout

Domain ← Application ← Infrastructure ← CLI and Revit plugin

Domain has no NuGet packages. NetTopologySuite, HiGHS, xBIM, and ImageSharp stay in Infrastructure behind ports in src/OpenRebar.Domain/Ports/. The Revit API is referenced only in src/OpenRebar.RevitPlugin/ under #if REVIT_SDK.

Port	Role
IIsolineParser	DXF and PNG zones
IReinforcementCalculator	Bars in a zone
IRebarOptimizer	1D cutting stock
IIfcExporter	IFC4
IRevitPlacer	Straight bars in a live document
IImageSegmentationService	Optional HTTP bridge. Offline. No hosted model

Column generation is the production cutter. It records when the dual bound is Proven. The fallback class is FirstFitDecreasingOptimizer; its loop keeps the open bar with the smallest remainder. Neither one is a claim of minimum waste on a real project.

Known limits

• One drawing is one layer. A project file can name up to four drawings.
• Anchorage stops at the working area. A hook is the centerline arc and has no straight tail until a profile sets hooks.tailDiameters. Couplers are not modeled. Openings are counted and are still inside the checked area.
• Column generation packs one stock length at a time.
• The schedule is CSV. XLSX is not written.
• IFC is IFC4. It is not an IFC 4.3 splice model, and it has not been round-tripped through a Revit importer in this repository.
• Revit placement of a hook, L, or U is refused. The schedule and the IFC remain the record.
• A PNG needs calibration (--px-per-mm and an origin). Frames above 25 million pixels are rejected before decode.
• examples/dxf/simple-slab at Ø20 and 30 mm cover: edgeDevelopmentAreaM2 6.12, realDeficitAreaM2 0.99, underReinforcedAreaM2 7.11.

Examples

• examples/dxf/simple-slab/ — free edges, area check fails, exit 2
• examples/png/simple-slab/ — the same slab from a calibrated PNG
• examples/fe-field/supported-slab.csv with supported-slab.project.json — slab on walls, area check passes

Regenerate snapshots with tools/examples/generate_expected_outputs.ps1 or .sh. Every changed figure belongs in the pull request.

The batch corpus is outside the push lane. Without OPENREBAR_BATCH_CORPUS_ROOT the corpus job writes corpus: NotEvaluated.

Optional ML lane

cd ml
python -m pip install --require-hashes -r requirements.locked.txt
python -m pytest tests -q
python scripts/validate_model_manifest.py models/MANIFEST.json

CI installs that lock with hashes on Python 3.11. There is no call to a hosted model. An empty manifest means the service has no checkpoint to run.

Revit

Copy addin/RevitNet8 next to the net8.0-windows build, or addin/RevitNet10 next to the net10.0-windows build. Bar axes sit at cover + d/2. The inner direction of a face lies on the outer one. Top cover is read from CLEAR_COVER_TOP. See RELEASE_POLICY.md.

Supply chain

• NuGet restore is locked.
• The ML lane installs ml/requirements.locked.txt with hashes and does not call a hosted model.
• Scorecard runs on main. A release builds an SBOM and attests the published files.
• ImageSharp stays on 3.1.12. Version 4 needs a license key. Five advisories on that line are accepted because that line has no patch. Any other high finding still fails the audit.

Documents

• docs/README.md — map
• docs/architecture.md
• docs/NORMATIVE_TRACEABILITY.md — clause, code, test
• docs/VALIDATION_BASELINE.md — how a public number is earned
• docs/SOTA_2026.md — gap list
• docs/OPENREBAR_AGENT_PLAN_r10_2026_10_14.md — current queue
• CHANGELOG.md, CONTRIBUTING.md, SECURITY.md, CITATION.cff

April 2026 audits under docs/archive/ are history.

License

MIT. See LICENSE.