BIM Knowledge Base
Practical definitions of the terms that matter in BIM and data-driven construction — how they relate to each other, and how we put them to work.
Fundamentals
BIM Dimensions
- 5D BIM Linking model elements to cost, so quantities and budget follow the design as it changes.
- BIM dimensions The idea of adding layers of information to the 3D model — time (4D), cost (5D) and beyond.
- 4D BIM Linking model elements to the construction schedule, so the build can be seen — and tested — in time.
- Quantity take off QTO Deriving measured quantities of materials and elements directly from the model.
- 3D BIM The coordinated geometric model itself — intelligent 3D objects carrying data, the base every other dimension builds on.
- 6D BIM Commonly the sustainability dimension — energy, lifecycle and carbon data on the model; not a standardised term.
- 7D BIM Commonly the facility/asset-management dimension — operations data linked to the AIM and COBie; not a standardised term.
Geometry & Modeling
Level of Information Need
- Level of Information Need LOIN The ISO 19650 framework that defines how much information is enough for a given purpose — no more, no less.
- Level of Development LOD Level of Development — the North American 100–500 scale for how far a model element has progressed, alongside Italy's LOD A–G and the ISO level of information need.
ISO 19650
- ISO 19650 The international standard series for managing information across the whole life of a built asset using BIM.
- Exchange Information Requirements EIR The specification of what information an appointment must deliver, when, and to what standard.
- BIM Execution Plan BEP The appointed party's plan setting out how a project's information requirements will be met.
- Information management The governance layer of ISO 19650 — specifying, producing, checking, exchanging and approving information across the asset lifecycle.
- AIM (Asset Information Model) AIM The information model that runs the asset in operation — the data the owner needs after handover.
- Information delivery plans (MIDP & TIDP) The schedules of who delivers what information, when — task-level TIDPs aggregated into the project-wide MIDP.
- PIM (Project Information Model) PIM The information model for the delivery phase — the coordinated project information for design and construction.
- Information requirements (OIR / PIR / AIR) The cascading statements of what information is needed — organizational, asset, project, and exchange.
- Information protocol The contractual schedule that binds ISO 19650 information obligations, the CDE and standards to an appointment.
Common Data Environment
- Common Data Environment CDE The single agreed source of information for a project, where every container is collected, managed and shared under control.
- CDE states (WIP / Shared / Published / Archived) The controlled statuses a container moves through inside the CDE, each with its own purpose and review gate.
- Information container The named, managed unit of information in the CDE — tracked by status and revision.
Roles
- BIM Coordinator The role running day-to-day model coordination — federation, clash detection and issue resolution.
- BIM Manager The role accountable for the BIM and information-management strategy on a project or across an organisation.
- ISO 19650 parties (appointing / lead appointed / appointed) The three contractual roles that hold information responsibilities — the client, the lead, and the parties they appoint.
- Delivery team & task team The team appointed for a project, and the working groups within it that produce the information.
Coordination
- Clash detection Checking combined discipline models for elements that occupy, or encroach on, the same physical space.
- Model federation Combining discipline models into one coordinated view without merging their authorship.
- MEP coordination Fitting mechanical, electrical and plumbing models into the available space so services install without clashes.
- Hard clash & soft clash The two main clash types — a solid overlap, and a clearance or tolerance violation.
- Model checking Quality assurance of a model — validating geometry, data and code-compliance against requirements.
- Issue tracking Recording, assigning and resolving coordination problems through to closure.
Interoperability
- buildingSMART International The industry body that stewards the open standards behind openBIM — IFC, BCF, IDS and more.
- IFC / openBIM IFC The open, vendor-neutral data standard (IFC) and the collaborative workflows (openBIM) built on it.
- BCF (BIM Collaboration Format) BCF An open format for exchanging model issues between tools — the comment and the clash, not the whole model.
- IDS (Information Delivery Specification) IDS A machine-readable, checkable specification of exactly what information an IFC model must contain.
- COBie (Construction-Operations Building information exchange) COBie A structured, non-geometric handover of asset and equipment data for facility management.
- MVD (Model View Definition) MVD A defined subset of the IFC schema that satisfies one specific information-exchange requirement.
- IDM (Information Delivery Manual) IDM The ISO 29481 method for capturing the processes and information exchanges across a project's lifecycle.
Reality Capture
- Scan to BIM Turning 3D laser-scan data of existing conditions into a BIM model.
- Point cloud The dense set of measured 3D points from a laser scan or photogrammetry — the digital "as-is" of a real space.
- As-built model The model of the asset as actually constructed — not as designed — capturing field changes and real conditions.
- HBIM (Heritage BIM) HBIM BIM applied to historic buildings — irregular geometry, reality capture, and conservation data.
- Laser scanning (LiDAR) Capturing as-built geometry as a point cloud by measuring millions of 3D points with a laser.
- Photogrammetry Deriving 3D geometry and point clouds from overlapping photographs.