inSITE

Site complexity analyser for NZ residential construction

inSITE is a single-file browser tool for analysing building site terrain complexity. Load an IFC terrain mesh, set your site parameters, and get an instant complexity score — with slope heatmaps, setback zones, flood level checks, solar shadow analysis, and 3D form model overlays.

Built for Aotearoa New Zealand residential construction, with NZS 3604 scope limits and council compliance rules built in.

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How to use

1. Download inSITE.html
2. Open it in any modern browser (Chrome, Edge, Firefox, Safari)
3. Drop your IFC terrain file onto the viewport
4. Adjust parameters in the left panel
5. Click ▶ Run analysis

No install. No server. No internet required. Works offline.

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What it analyses

• Slope — heatmap per terrain triangle, NZS 3604 scope threshold flagging
• Elevation — colour-banded terrain surface
• Aspect — compass orientation of each slope face
• Setbacks — inward-offset zones from cadastral boundary (front/side/rear)
• MFL — Minimum Floor Level compliance against council flood data
• Shadow — solar shadow outline and fill draped on terrain surface (SPA algorithm)
• Form models — 3D massing overlays (IFC, OBJ, STL) with ground intersection

Outputs a Site Complexity Index (0–100%) and an Impacts on Feasibility table.

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IFC requirements

Terrain mesh

IfcGeographicElement
  Name            = anything
  PredefinedType  = .TERRAIN.
  Geometry        = IfcPolygonalfaceSet or IfcTriangulatedFaceSet

Export from Bonsai BIM using the standard terrain mesh export. IFC4X3 (IFC4X3_ADD2) required.

Title boundary

IfcGeographicElement
  Name            = anything
  ObjectType      = 'TitleBoundary'   ← exact string, case-insensitive match
  PredefinedType  = .USERDEFINED.
  Geometry        = IfcIndexedPolyCurve or IfcPolygonalfaceSet

Draw the cadastral boundary as a closed polyline in Bonsai, assign as IfcGeographicElement with ObjectType = 'TitleBoundary'.

Road frontage (optional)

IfcGeographicElement
  ObjectType      = 'RoadFrontage'
  Geometry        = 2-point line snapped to the street-facing boundary edge

Without this, use the ↖ Click street boundary edge fallback in the left panel.

Form model (optional)

Any IfcPolygonalfaceSet geometry in a separate IFC file, OBJ, or STL.
Convention: model Z=0 = finished floor level. Use Offset Z in the left panel to position on site.

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FOSS requirements

inSITE is built to strict free and open-source principles. These are non-negotiable for this project.

Core rule: no closed-source dependencies

Every library, algorithm, and data source must be:

Requirement	Detail
Open source	MIT, Apache 2.0, BSD, ISC, or public domain licence
Browser-native where possible	Canvas 2D API, vanilla JS — no build tools required
No proprietary APIs	No paid services, no API keys, no cloud dependencies
No telemetry	No analytics, no tracking, no external requests
Offline capable	Must function with no internet connection
Single-file deliverable	All code in one .html file — no npm, no bundler, no server

Why this matters

inSITE is intended for use in locked-down government and local government environments (NZ public sector, Kāinga Ora programme teams, councils). These environments often block external CDNs, prohibit cloud tools, and require air-gap capability.

Current dependencies

Component	Licence	Notes
Canvas 2D API	Browser-native	Zero external
SPA sun position algorithm	Public domain (NREL)	Implemented inline
IFC parser	Custom, written for this project	No web-ifc or IfcOpenShell required
OBJ / STL parsers	Custom, written for this project	Pure JS, ~60 lines each
DM Sans font	Open Font Licence	Loaded from Google Fonts — can be self-hosted for full offline use

Contributions

All contributions must comply with the FOSS requirements above. Pull requests that introduce closed-source, proprietary, or API-key-dependent code will not be accepted.

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Bonsai BIM workflow

1. Import terrain survey (DEM, point cloud, or contour data) into Blender using BlenderGIS
2. Generate TIN mesh and assign as IfcGeographicElement with PredefinedType=TERRAIN in Bonsai
3. Draw cadastral boundary polyline, assign ObjectType='TitleBoundary'
4. Export IFC4X3 from Bonsai
5. Drop into inSITE

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Test files

File	Description
inSITE-TestTIN-Ifc43-v1.ifc	Small test TIN with title boundary (IfcPolygonalfaceSet format)
Stanmore2.ifc	Real site TIN with title boundary (IfcIndexedPolyCurve format)

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Roadmap

• Perspective toggle for orbit view
• Draggable panel splitters
• SVG + PDF report export (Dasu.print integration)
• District Plan GeoJSON overlay import
• Services connection point mapping
• Site comparison mode (multiple IFC files, same ruleset)
• Recession plane analysis (per boundary edge)
• IfcArcIndex curved boundary support

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Related projects

• Dasu.print — single-file drawing sheet layout tool for Bonsai / OSArch
• IfcSieve — browser-based IFC geometry stripper and data extractor
• Bonsai BIM — open BIM authoring in Blender

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Licence

MIT

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Built by Nigel Lamb · Christchurch, Aotearoa New Zealand
Part of a FOSS AEC toolset alongside Dasu.print, IfcSieve, RainIn, and TAKT-it