Level Of Detail (LOD) Explained: LOD2, LOD3 & LOD4

LOD defines the complexity, accuracy and completeness of BIM model elements.
It ensures:

• Everyone knows what will be included
• No incorrect assumptions are made
• Pricing and scope are clear
• Modelling meets the needs of the project stage
• Designers are not misled by missing or overly simplified geometry

In a Scan-to-BIM context, LOD is tied directly to:

• The accuracy of the point cloud
• The complexity of the building
• The intended use of the BIM model
• The level of decision-making it supports.

Different countries interpret LOD in different ways.
We use a UK-friendly interpretation informed by BS 1192, PAS 1192, industry guidelines and practical Scan-to-BIM delivery.

LOD2 – Conceptual / Massing

LOD3 – Architectural & Structural General (Most common for Scan-to-BIM)

LOD4 – High Detail / Fabrication-Ready As-Existing

Each level is explained in detail below.

LOD2 provides an outline representation of the building or environment, most suitable for:

• Early feasibility
• Planning
• Basic coordination
• Context modelling
• Massing studies
• Large-scale site representations

What LOD2 Includes

LOD2 models typically contain:

• Overall building shape
• Roof form and basic geometry
• Approximate openings
• Simplified floor levels
• Basic terrain or topography
• Context buildings (simplified)

LOD2 Accuracy

Accuracy is generally in the range of 50–100 mm.
Surfaces may be simplified and fine detail is not shown.

Why Choose LOD2

• Lowest cost
• Fastest modelling turnaround
• Suitable for concept design
• Ideal for large estates or campus-wide modelling

LOD2 is not suitable for detailed design or refurbishment planning.

The most common Scan-to-BIM level across UK projects

LOD3 is the standard level used for most refurbishment, redevelopment and design projects.
It provides a highly accurate representation of the building’s geometry without the extreme detail of fabrication-level modelling.

What LOD3 Includes

LOD3 typically includes:

Architecture

• External and internal walls
• Primary structural elements
• Floors and slabs
• Roofs, parapets, ridges and gutters
• Doors and windows with correct sizes and positions
• Stairs, ramps, balustrades
• Openings, recesses and soffits
• Building fabric features visible in point cloud

Structure

• Primary columns, beams
• Structural penetrations
• Visible foundation edges
• Primary roof structures (if visible)

MEP (if included)

• Ducts, pipes and trays above agreed diameter
• Plant volumes
• Extracts, risers, major services routes

LOD3 Accuracy

Typical tolerances: 15–30 mm

This level of accuracy is sufficient for:

• Design development
• Coordination
• General detailing
• Costing
• Refurbishment planning

Why Choose LOD3

LOD3 offers the best balance between:

• Cost
• Detail
• Accuracy
• Delivery time

It is the default recommended level for most Scan-to-BIM projects unless otherwise specified.

For projects requiring maximum accuracy and precision

LOD4 provides a very high level of geometric detail, suitable for:

• Heritage documentation
• Façade retention
• Industrial environments
• Spaces with technical complexity
• Fabrication planning
• High-precision modelling
• Detailed clash detection
• Conservation & restoration projects

What LOD4 Includes

LOD4 captures:

• Detailed profiles
• Exact mouldings and trims
• Heritage ornamentation
• Steel sections and profiles
• Secondary structural elements
• Structural bracing
• Mechanical plant geometry
• Accurate structural interfaces
• Detailed roof geometry
• Detailed architectural features

LOD4 Accuracy

Typical tolerances: 0–15 mm

This level requires:

• Higher-density scanning
• Specialist modelling techniques
• More modelling time
• Additional QA checking

Why Choose LOD4

• Needed where design decisions depend on millimetre accuracy
• Essential for heritage
• Important for contractors working around complex existing conditions
• Required for fabrication-level geometry

LOD4 often involves collaborative decision-making about what should be modelled to this detail.

LOD determines:

• Required scan density
• Scanner type
• Number of scan positions
• Access needs
• Whether intrusive surveys may be needed

For example:
Higher LOD → More detail → More accuracy → More scans → More modelling time.

It is important to separate:

• LOD = geometric detail
• LOI = non-geometric information

We can deliver LOI to match:

• Asset management requirements
• Uniclass classifications
• COBie attributes
• Client-specific metadata

But LOI is always agreed separately, not assumed.

If unsure, we help you select the right LOD based on project scope, required deliverables, accuracy needs and budget.

Because our LOD definitions are clear and documented, project teams benefit from:

• No ambiguity about what is included
• Predictable scope and pricing
• Better design coordination
• Reduced rework from missing or inaccurate geometry
• Clear modelling boundaries
• Faster design decision-making
• Accurate representation of existing conditions

A defined LOD strategy is the backbone of a successful Scan-to-BIM project.

Return to the full Scan-to-BIM Survey Specification.

Tel: 07731 747329
Tel: 07928 653296
Email: info@towersurveys3d.co.uk