From laser scanner surveys to Point Cloud and BIM modelling. The advantages of Scan to BIM in construction projects.
In this article we’ll take a detailed look at construction site surveys from a Scan to BIM perspective based on laser scanner and point cloud workflows also covering some of the main advantages that can derive from integrating these new technologies into building redevelopment projects.
In particular, we’ll see how to produce the 3D BIM model of a building starting from a laser scanner survey with SLAM technology.
But what is a Scan to BIM process?
Scan to BIM is the process of creating the BIM model of a building or an existing space, starting from the data acquired from the survey carried out with advanced technologies, such as 3D laser scanning, Structure for Motion and high-definition photogrammetry.
The survey outcome is a point cloud or 3D mesh that can be used as basis for BIM modelling.
Why use SLAM technology
Any kind of construction intervention always starts from some sort of geometric survey of the building.
In addition to traditional methods, there are also some very efficient and quick surveying techniques that allow you to get a 3D model of the whole building in a few steps and with a great degree of precision.
One of the most ground-breaking technologies is with laser scanners and SLAM technology, a tool capable of scanning the surrounding environment while walking around and inside the building (over 300,000 points can be detected per second and up to a distance of 100 m).
SLAM (Simultaneous Localization And Mapping) is a basically a technique that allows you to moves with a high-precision scanner capable of mapping the environment and building up a map in real time even without disposing of a GPS signal.
In practice, with this type of laser scanner, all the operator has to do is take a walk (either inside or outside) while the device takes care of generating the point cloud.
This surveying process (namely, Scan to BIM) provides great advantages such as:
- it allows a high reduction in the acquisition process compared to traditional surveying methods
- it allows you to produce survey related info by simply walking around
- it does not require any special skills or technical knowledge
- it only requires one person to survey even very complex buildings
- acquisition of both the exterior and the interiors of a building
- it allows you to achieve a very high degree of precision
- it provides all the data to be processed and analysed comfortably from your office with a single survey campaign
- it also detects environments where there is no GPS signal
- it is also very effective on historical buildings with irregularities and spaces that are difficult to survey using other methods
- it allows you to easily switch from the asset’s current situation to the BIM model.
From a Laser Scanner survey to the BIM model
Let’s have a look at this case study in which we generated the 3D Model of a building starting from a survey carried out with GeoSLAM technology.
Building survey with geoSLAM
In this case study, we conducted a survey of a historical building using the GeoSLAM Horizon. There was no need to bring additional devices or tools to the site and the entire campaign was carried out with a single operator.
We started off with surveying the building interiors. Once the Scanning equipment was ready and set up, we simply took a walk around the spaces at normal pace avoiding sudden movements, inside each room to be surveyed.
In a just under 10 minutes we completed the scanning campaign and acquired the whole building with its interior environments.
At this point we could move on to surveying the facades.
The technique was the same, we just needed to walk along the building’s perimeter walls. After that, we could download the scan results into the geoSLAM software comfortably from our office and view the detected point cloud and the route we followed during the survey.
In just a matter of minutes and with very little effort we obtained a very detailed and complete point cloud. In addition, having surveyed both the interior and exterior of the building, we also obtained the walls thicknesses and all information needed to prepare project drawings and documents. This obviously means that further inspections aren’t necessary as we already have all the information that we need.
At this point, withthe point cloud file already available, we were able to export it in the different file formats (.LAS, .LAZ, .E57, etc.) and then import it into our BIM software.
Uploading a point cloud to usBIM.pointcloud
Before importing the point cloud into Edificius, the BIM Authoring software used for the architectural modelling process, we need to upload it to the usBIM platform cloud environment. Edificius takes advantage of the usBIM visualization and storage functions to manage even large point clouds and access files that can be easily shared with other collaborators too.
usBIM.pointcloud offers many functions for managing the point cloud directly online and without having to install any software on the PC.
For example, you can:
- store large point clouds
- view files online from your browser without using any specific software installed on your PC
- share data and information with other team mates via a simple link, without copying and duplicating heavy files
- view point clouds in .PTS, .XYZ, .PLY, .E57, .LAS, .LAZ, .XYZCIRN and .ASC formats directly online
- navigate textured mesh models directly with the browser
- take measurements on the model
- federate and manage different file formats
- instantly create infinite model sections
- add extra information to the model.
3D modelling from Point Clouds with Edificius
The BIM modelling phase is just as simple and fast thanks to the functionalities of the Point Cloud environment in Edificius.
From the Point Cloud environment, we can import the survey previously uploaded to usBIM, and use Edificius to manage the point cloud as generated by the laser scanner survey.
We can, for example, generate cross-sections of the Point Cloud cluster, manage visibility for the various objects (cloud, section planes, etc.), manage levels and use the automatic recognition tools to build up the 3D model quickly.
First of all, we’ll define the levels and dimensions of the building’s floor levels.
This proves to be a very useful process because we can calibrate the BIM model’s floor level definition to the point cloud and therefore align it with the HRS reference system.
We can also enter the elevation reference system editor to make further customisations according to any special requirements and have the maximum flexibility to manage the various levels. We can act both according to the point cloud and manually, intervening on the measured values or even adding other planes that we may not have detected with the laser scanner.
We can obtain an infinite number of cross-sections (vertical and horizontal) and take a lot of information directly from the point cloud.
To easily create the BIM model directly from the cloud (Scan to BIM) we use the automatic functions in Edificius, which act as accelerators that allow us to insert the walls using the point cloud as an overlayed reference.
We can then move on modelling the vertical envelopes using the point cloud as a guide. Moving on to the envelope, we’ll click on the point cloud icon to take advantage of other automatic features provided by the software. Next, by simply outlining the length of the wall based on the points in the cloud and choose the alignment, thickness, section (constant or variable), angle, etc.: the software will automatically detect length, width and thickness.
We can quickly trace all the walls thanks to these accelerators and we can also define the material layers and materials, choosing objects from the catalogue.
Let’s also insert the windows and model its width. An editor will automatically be activated to easily position the window at the right height, correctly specify its height and define the approximate values according to our needs.
From the properties we can also specify the type of glass, the frame and the thermal transmittance of each individual window to obtain a complete model full of useful information.
In the same way we insert the internal doors, always using the point cloud recognition.
In a few steps we obtain a 3D model that faithfully reproduces the actual state of the building surveyed.
With a simplified input we were able to create our BIM model from the point cloud that we imported from usBIM.
With this model it now becomes much easier to obtain all the working drawings completed with floor plans, elevation views, cross-sections and 3D views. We can also generate static renders, real-time renders and video presentations.
At this point we can export the model in IFC format to facilitate collaboration with other professionals even if they’re using other BIM software.
Edificius also allows an IFC export optimised for ACCA so that we can obtain an IFC .zip file containing all the elements, material layers, fixture types and all the properties and characteristics that we previously assigned.