The use of laser scanning, and in particular point cloud laser scanning has been popular now for a number of years. Increasing renovation and refurbishment projects, especially for older buildings, means that rather than demolish a building and rebuild on the site, an existing building can be updated, allowing use of the existing facade, while changing the interior to modernise or improve the layout for the uses that are required.
The use of an accurate model to define the ‘existing condition’ of a building before any further design work is undertaken is essential for both, architectural as well as engineering teams. Until the laser scanning surveys using 3d laser scanning technology were introduced, a physical survey of the building was the only way in which to obtain an accurate survey of a building.
The advent of CAD and BIM technology used during design stages has called for accurate 3D architectural modeling from the start and therefore 3d laser scanning is a much more accurate and useful tool for such purposes.
While considering the benefits for both architectural and MEP projects, the benefit of using point cloud scanning is profound.
Firstly, for an architectural project, there is usually a call for the re-design of the architectural space inside a building. These may be changes, mainly to the internal space may also impact some external aspects, either way, an accurate representation of the current model is required because existing drawings may be outdated or maybe too old to use in the digital environment. Once a laser scan is completed, the creation of a 3D BIM model for the existing space makes the architectural design much easier. Typically, architects will also use existing plans and information as well as the laser point cloud scan to create the new ‘existing condition’ model, although they will predominantly rely on the laser scan data for creating a new model and associated architectural layout drawings or general arrangements (GA’s).
In most cases, the MEP systems are not taken from an existing laser point scan survey and modelled. Rather, in most cases, the MEP systems are created from a clear base and are based on a new design altogether to suit the new purposes and uses of the refurbished building.
For building service engineers and BIM modellers, the laser scan model is therefore also extremely useful. The remainder of this blog focuses on the existing MEP services being completely stripped and therefore not those that may have appeared in the laser point cloud model, allowing for a new set of services to be added.
The importance of 3D architectural modeling created from point cloud laser scan for building services engineers and designers can be summarised as follows;
Awareness of architectural and structural elements - For MEP modelling an accurate architectural model will provide exact information about false ceiling levels, upstand beams, columns heads, external and internal walls. It will also provide information about riser areas and core services areas. MEP design engineers will then work around these architectural and structural elements when mapping out their services.
Builders work holes - When planning larger MEP services such as drainage sprinkler and ductwork, an MEP engineer will create builders work or penetration openings in the structure of the building. The point-cloud data for MEP engineers will show existing builders work and penetrations and therefore this information can be helpful. The building services designer may choose to use the existing holes (saving additional work) or request new holes for his/her services to pass through.
The accuracy of drawings – When a 3D BIM model is created, the BIM modeler will also create a number of coordinated drawings and single services drawings. These drawings include dimensions on them and these dimensions, especially for refurbishment projects are usually taken from existing walls and existing slab levels and floor levels. If the floor levels and all levels are based on an inaccurate model, then the MEP installation will also fail to some extent. The point cloud model and the accurate dimensions created from the same are therefore of significant value.
As discussed, the use of laser point - cloud 3D survey models for architectural purposes and also MEP services in particular, can be critical for a refurbishment project. Reliance on the data from the laser scan survey, assuming an accurate 3D model is created from that data, is very important to avoid construction issues and delays. Compared to legacy drawings, which may or may not have been updated, or traditional manual surveys, the accuracy of laser cloud scans and the models created from the same, will continue to remain an important aspect for modern construction design to meet cost and schedule challenges.
