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Geometry data describes the spatial shape and position of objects – as points, lines, surfaces or volumes, in 2D/3D. In construction, it includes dimensions, coordinates, orientations and relationships between building components, rooms and buildings. As geometric data, it forms the basis for digital models and reliable as-built surveys.
Why is geometry data important?
Building decisions are based on data. The more accurate the geometry data, the more reliable planning, construction and operation become.
Precise geometry data enables:
- reliable area and volume calculations
- accurate floor plans, sections and elevations
- digital as-built models and 3D models
- BIM workflows
- energy analyses
- quantity takeoffs and cost estimates
- digital twins of buildings
Especially for existing buildings, up-to-date geometry data provides the basis for well-founded decisions in refurbishment and modernization projects.
How geometry data is created and used in practice
- Capture: Digital building survey using terrestrial laser scanning (TLS), mobile LiDAR/SLAM or photogrammetry → point clouds, orthophotos.
- Processing/QA: Registration, check points, RMS errors, tolerance classes, removal of outliers.
- Modelling/derivation: Scan-to-BIM (IFC) or plan derivation (DWG/DXF/PDF), orthoprojection for facades, area calculation according to standards such as DIN 277. Point clouds are used to create BIM models or reliable planning documents.
- Storage/exchange: Open formats and clear references, such as coordinate system, units and versions, ensure interoperability and secure data exchange.
- Use: Quantity takeoff, clash detection, layouts/variants, CAFM master data, energy assessments, monitoring.
Quality criteria
- Accuracy/tolerance: e.g. mm/cm classes with documented measurement methods.
- Completeness/density: sufficient scan density, closed surfaces/volumes, no gaps or blind spots.
- Referenceability: coordinate system (local/UTM), origin/zero point, units (m/mm).
- Versioning/provenance: date, device/setup, QA reports, change log.
- Semantics: building element classes, rooms, attributes for BIM/CAFM.
Geometry data vs. attribute data
- Geometry data: shape/position, e.g. a wall as a surface or volume.
- Attribute data: describes properties such as material, fire protection class or year of construction.
Best practice: Link both data types in BIM/IFC to support planning and building operation.
FAQ
How do I ensure the quality of geometry data?
By defining tolerances, using check points with RMS evaluation, documenting methods and versions, and performing plausibility checks such as totals, deductions and sections.
Which formats are suitable for data exchange?
For point clouds, E57/LAS/LAZ; for 2D, DWG/DXF/PDF; for BIM, IFC. Always include the coordinate system, units and version.
How do I link geometry data with attribute data?
Through BIM models using IFC PropertySets, room books such as CSV/IFC, CAFM interfaces and unique IDs, so that geometry and attributes remain synchronized.