BIM and CAD modelling has its own logic – and one of the most common misunderstandings is confusing two fundamentally different parameters: model accuracy and level of detail, known as LOD. Many investors and project managers assume that the more detailed the model, the better. In practice, however, pursuing maximum detail without a clearly defined purpose is one of the most common reasons for budget overruns – with no proportional increase in the value of the data delivered.
Accuracy – Conformance with Reality
Accuracy describes how closely a 3D model reflects reality in terms of dimensions, geometry and the spatial position of elements. It answers the question of whether a pipe in the model sits exactly where it sits in the actual plant – and whether its diameter, length and centreline position match what was measured on site.
Importantly, a model can be highly accurate whilst having low geometric detail. A pipeline represented as a simple cylinder, perfectly matched dimensionally and spatially to point cloud data, is a high-accuracy, low-LOD model. And in many engineering applications, that is exactly what is needed.
High accuracy is an absolute requirement wherever spatial precision matters – primarily at the connection points where new pipework ties into existing infrastructure, such as vessel or equipment nozzles. Even a deviation of a few millimetres can determine whether a prefabricated component fits on site. For clash detection or general pipe routing, however, millimetre accuracy is not required.
LOD in BIM and CAD Modelling – What Level of Detail Actually Means
LOD, or Level of Detail, describes something entirely different: the geometric complexity of the model and the amount of information assigned to each element. It answers the question of how much detail the representation of a given element contains. A pipeline at LOD 200 is a simple cylinder. The same pipeline at LOD 400 has modelled flanges and supports – every detail represented geometrically.
The key point: high LOD does not guarantee accuracy. A model can be visually highly detailed whilst being positioned incorrectly relative to the actual plant layout. Detail and accuracy are independent parameters – you can have either without the other.
For a detailed breakdown of the LOD levels used by 3Deling, visit our service pages:
The Over-Detail Trap
Increasing the LOD level drastically raises project costs. Every additional detail – a flange, a bolt, a gasket – requires manual work from an experienced engineer. Multiplied across hundreds or thousands of plant components, those hours translate into sums that are difficult to justify against the actual technical value delivered.
Moreover, models with very high LOD are computationally heavy. Working with them requires powerful workstations, and simply opening and navigating the model can be time-consuming. On large industrial projects, where a model covers hundreds of metres of pipework, excessive geometric detail can effectively paralyse the design team’s work.
When High LOD Adds No Value
On many industrial projects, the design team works simultaneously across several data sources: a CAD model, a point cloud, and 360° panoramas accessible through the Webpano platform. In that working environment, details that would require high LOD in the model – valve type, nameplate designation, gasket specification – can be verified directly in the panorama, without any need to model them geometrically.
This means that in many cases the optimal solution is a model with high spatial accuracy and moderate LOD, supplemented by access to the point cloud and panoramas as sources of detailed visual information. This approach delivers all the necessary data at significantly lower cost than pursuing maximum geometric detail.
How to Define Requirements
Before commissioning modelling work, it is worth asking a few specific questions:
- What will the model be used for?
- Will it be the basis for prefabrication, where spatial accuracy to the millimetre is critical?
- Will it be a tool for planning a plant modernisation, where editable geometry is needed but not necessarily every bolt detail?
- Will it form the foundation of a Digital Twin system, where technical attributes matter more than visual complexity?
- Will it serve multi-discipline coordination on a construction project, where detailed representation of structural, mechanical and architectural elements is required for permitting or prefabrication?
The answers allow requirements to be defined precisely – separately for accuracy and separately for LOD – and help avoid commissioning detail that gets paid for but never used.
At 3Deling, every modelling project begins with a conversation about its purpose. The LOD level is tailored each time to the actual requirements, whilst spatial accuracy – grounded in a precise point cloud and a stable control network – remains as high as possible regardless of the chosen level of detail.
A clear distinction between accuracy and detail is one of the most effective ways to optimise a budget without sacrificing the engineering value of the model. It is worth paying for what is genuinely needed – not for what looks impressive in a specification.
Want to define the right accuracy and LOD requirements for your project? Get in touch – our experts will help select the model parameters that ensure technical integrity without generating unnecessary costs.
