An overview of 3D Laser Scanning Process with Scan to BIM
Scan to BIM Services is a process of capturing scanned data from the real site conditions in the form of 3D Model with the help of a scanner. It is useful for carrying out renovation projects, retrofit, and conversion projects. It can also extract accurate and precise construction information from as-built buildings.
It can be used as the production of comprehensive BIM Services Model, application of facility management, valuation purposes of existing structures or building can be procured easily, review of the plan that is altered or added, evaluating aspects of energy efficiency audit and creation of virtual tour of existing structures. It is based on the critical features of scanned data which includes geometry, mesh modeling, topography extraction, etc.
Use of laser scanner by contractors
Contractors gather on-site information with the help of 3D Laser scanners of their project, which helps them to get accurate data that can be further be used in all the construction and planning process.
There are multiple uses of a laser scanner for the contractors:-
- It helps to check the progress of a model.
- It can generate accurate as-built models from existing buildings.
- It can add any missing element or design to the model.
- It works to inspect the as-builts model.
It can be beneficial to the contractors within the construction industry as follows:-
Less rework from human error:- In certain construction projects, there is often a need to do rework on aspects of the model which takes a lot of time than expected and incurs more cost than estimated while planning stage. With the advent of a 3D laser scanner, we can reduce the need for rework before the model being built. Revit software can take existing elements of a model and redesign it which can save costs and prevent rework. Manipulation of 3D representation model can be done through Revit where 3D laser scanners can fetch all the essential information about the model. Any measurement can be gathered from the scanned data or point cloud model.
Evaluating documentation throughout the construction process: – Scanner is not just used for capturing data from existing building conditions or pre-built projects, but it can also be used for documenting your project throughout any project’s lifespan. Any changes in the model can be made quickly and tracked or can be useful to send a scan to stakeholders of the project. It can make them track the update and keep team ahead of schedule.
Reduction of costs and schedule: – By keeping documentation of stages of the building model and reducing rework can reduce the cost, which can drive an accurate and updated schedule. It can help to know what materials are needed and determine the actual costs with laser scan additional plug-ins to your software. The material can be manipulated and fetch data for overall material and supply information of the project. By this, everyone can be informed about material and supplies to accomplish any given tasks.
High Precision Data: – It helps to capture all the useful information and high precision data helps the point cloud model to provide all the information necessary to complete a project. 3D scanners can capture a single pixel and offer the ability to manipulate the existing condition. By this technology, we don’t have to worry about human errors. All the information captured can be needed by the contractors to get the tasks completed effectively and efficiently.
How does Scan to BIM Work through 3D laser Scanners?
Scanning: capturing data
The laser scanner is placed on a tripod, and the laser rotates in very high speed and captures the surrounding site. However, the laser is not harmful to the naked eyes.
The process of scanning is straight forward, the laser beam captures the surface, and the relative position between the surface and scanner is recorded as X, Y and Z values commonly called as a ‘point.’ And an accumulation of these points creates a precise 3d digital picture, called as a Point Cloud Modeling. After capturing millions of points, the scanner will capture color images, through which colored representation of the scan data is generated.
To get accurate and précised scanned data to a BIM Model, there are certain steps to be taken. We can keep a check on our scanning process and make it more useful and fruitful by understanding the requirements and maintaining an audit of the following:
– The purpose of the point cloud should be clear to the team before they visit the site for scanning. This will increase the efficiency of the capturing of the point cloud data for the project.
– When a team reaches on-site to capture the point cloud, they must set up the scanner and prepare it with a few inputs regarding the number of points to take for a single scan and the density of scan.
– The scanner captures only the visible surfaces. To get a clear 3d digital presentation of the surroundings one will have to take multiple scans from different directions as well as different angles. When we know the purpose of the scan that what the particular scan will be used for in future we will be quicker and fast while getting the 3d scan.
– We will now have to take this data into a system. All the individual scans must be registered into a single point cloud. We can use point cloud software to register, review, and model the data.
– Once the registration is completed, we can import this point cloud into the 3d modeling software and start creating the model.
With laser scanners and point cloud data, we can achieve the desired accuracy and speed in our 3d models. The on-site information and the documentation work can get easily synchronized, saving us from working on the long old trial and error method.
We can get our point cloud data in the following formats and then we will require converting these formats into the listed formats to get the point cloud imported in Revit:
Formats in which we can receive the scanned data
- Sequence of images
There are multiple softwares which can be used to convert the scanned data formats into Revit further supported point cloud format such as:
- Autodesk Recap
The Revit supported formats of point cloud data are:
Process of Modeling with Point Cloud Software
– After importing, the point cloud in Revit, the density of the cloud will play the key role; higher the density greater will be the accuracy in geometry.
High Density Scan Data
Low Density Scan Data
- Required time depends upon the scale of details we are focusing on; if we are focusing on minute details, we will require more time for modeling the entire project.
- Once the point cloud is placed in the project (by origin to origin/by center to center/ by shared coordinates or by last-place settings), we can commence modeling.
- The scan visible in the floor plan shows gaps in between the walls (the scanner captures the surfaces only). So where we find the edges, we will create ‘detailed lines’ all through the walls everywhere.
- Now, we will place walls over these lines, we should practice the model creation this way only to avoid errors and maintain accuracy.
- This is because the scan generally gets deflected, the bottom and top of the wall most of the time do not match. Therefore we create the walls according to the bottom of the scan (TIP).
- Later on, we continue pacing elements the same way.
- Revit with Recap is the oldest method of working on scans though. Nowadays there are software like Edgewise, ImaginIt, PointSense, etc. which generates model geometry from the point cloud data itself, after that we have to finish this geometry with proper categories of elements.
What is the QA/QC process and how it can be useful to the construction industry?
After completing the 3d model, it is recommended and required to do the thorough quality checking of all the elements by overlaying the scan with the model and rectify any errors or mismatches between the scan and elements.
Moving forward with the process of QA/QC of a model, we should be well aware of the tolerances which we have kept for modeling. The tolerances are dependent on two factors:
- Level of Detailing of the project
- Density and Clarity of Scan
By tolerances we mean, that how much leverage we will give to elements and their accuracy while modeling and on the factors mentioned above we can decide until what percentage we should take tolerances.
Point Cloud to BIM Services helps save time in comparison to the traditional method. The construction cost can be reduced to a certain extent as the BIM model can help to identify the pars of the building to be worked upon in the primary design phase. We can even generate the energy analysis and ensure the quality of the work which has to be done on-site through these BIM models.
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