Survey

BIM modelling from survey data

The survey point cloud, from laser scanner, drone or photogrammetry, becomes the BIM model of the existing conditions: the basis for any work on existing assets.

At a glance

BIM modelling from survey data, or scan to BIM, turns the point cloud of a survey carried out with a laser scanner, drone or photogrammetry into a BIM model of the existing conditions, with geometry and data at the level required by the exchange information requirements. The survey is carried out by the surveyor appointed by the client; B1P Group supports the client in BIM modelling from survey data: it checks that the survey is fit for the model uses and models it in BIM, for refurbishments, building services upgrades, historic buildings and infrastructure, across Italy.

Definition

What is scan to BIM?

BIM modelling from survey data, also known as scan to BIM, is the step from a digital survey (point cloud from laser scanning, drone or terrestrial photogrammetry) to an information model of the existing asset. The point cloud describes the surface as it is; the model interprets it as meaningful objects (walls, floors, columns, pipes, tracks) with the data the design needs.

The level of detail and accuracy is not a fixed standard: it is decided according to the model use, ideally before the survey is carried out. A building services upgrade calls for different tolerances and information content from a structural assessment or a restoration.

Deliverables: BIM model of the existing conditions in Revit or Civil 3D, IFC export, survey modelling report with the model tolerances and interpreted areas, 2D drawings from the model if required
Standards: UNI 11337-4 for the levels of development of objects, the client's exchange information requirements for model uses and information levels, ISO 19650 for delivery
Data and tools: Registered point clouds (E57, RCP, LAS), orthophotos and photogrammetric data supplied by the surveyor; Autodesk ReCap for reading point clouds, Revit and Civil 3D for modelling

BIM modelling from survey data

When is scan to BIM needed?

When work is planned on an existing asset and the original drawings are missing, incomplete or do not match what was built. This is the case for refurbishments, seismic and building services upgrades, property subdivisions, the restoration of historic buildings and infrastructure in operation, where a traditional survey cannot describe complex geometries in a useful timeframe.

It is also needed by those who must deliver an as-built model at the end of the works: the survey of the finished asset, turned into BIM and compared with the design model, documents the differences and updates the model to be handed over to the client.

BIM modelling from survey data

How do you get from the point cloud to the model?

We start from the model uses: tolerances, level of detail of the objects and data to be attached. If the survey has not yet been carried out, we tell the client and the surveyor the coverage, accuracy and formats needed for modelling. Once we receive the registered and georeferenced point cloud, we check its coverage and quality and model in Revit (buildings) or Civil 3D (linear infrastructure and terrain), element by element, with families and parameters that comply with the information requirements.

Every object in the model keeps its link to the point cloud: areas not covered by the survey, or interpreted, are stated in the survey modelling report, so whoever uses the model knows where the geometry is measured and where it is reconstructed.

BIM modelling from survey data

What level of detail should you ask for?

It depends on what the model is for. For a feasibility study, volumes and envelope are enough; a detailed design needs structure, partitions and main building services; a building services upgrade needs actual routes, diameters and dimensions. Asking for maximum detail everywhere costs time and produces a heavy model that nobody uses.

B1P Group proposes the level for each discipline and writes it into the offer, with reference to UNI 11337-4 and the information requirements: the client knows in advance what they will receive and the designer knows what they can rely on.

Deliverables

What do you receive, and at what level?

Three typical configurations; the actual configuration is defined in the offer according to the model uses.

Model use	What it includes	Typical level
Feasibility and volumes	Envelope, floors and main openings, areas and volumes from the model	Simplified geometry, area and use data
Refurbishment design	Structure, partitions, openings, main building services, dimensions and schedules	Geometry from the point cloud with stated tolerance, parameters per discipline
Building services upgrade and as-built	Actual routes and dimensions of services, plant rooms, clashes with the structure	Detailed geometry in the work areas, component identification data

Related services

What does it combine with?

Frequently asked questions

Frequently asked questions about scan to BIM

Do you also carry out the survey?

No. The survey is carried out by the surveyor appointed by the client; we support the client in BIM modelling from survey data. If it has not been done yet, we specify the coverage, accuracy and formats that the model uses require, so the point cloud arrives ready for modelling.

How accurate is the model?

It depends on the accuracy of the survey and the level of detail chosen: the model cannot be more accurate than the point cloud it comes from. In the survey modelling report we state the tolerances per discipline and the interpreted areas, so that whoever uses the model knows where the measurements can be trusted.

Is a drone survey enough, or do you need a laser scanner?

It depends on the asset and on the model use. A drone covers roofs, tall façades and large areas; a terrestrial laser scanner captures interiors and details with an accuracy that aerial photogrammetry lacks. We work with both and with a combination of the two.

How long does it take?

Modelling takes weeks, in proportion to the areas, the disciplines and the level of detail. In our offer we state the delivery times from receipt of the point cloud, so the client can plan the survey and the design.

Contact

Do you have a survey to turn into BIM?

Tell us what you need it for: we will propose the right level of detail, with timescales and deliverables in writing.

Request a meeting B1P Group's BIM consultancy