What Is A Point Cloud?
We explain what exactly a point cloud is and how they are obtained.
Article By: Tom Ayre | Last Update: June 2022
In this article, we explain what a point cloud is and how useful they are when designing construction and engineering projects.
Having an accurate as-built survey of your project is a crucial way to ensure your project is built correctly and efficiently. A 3D laser scan and production of a point cloud is the modern way of accurately surveying and getting spatial data for projects.
Let’s begin!
Point Clouds
3D laser scanning is undertaken using a 3D scanning device that accurately records geometric data in the X,Y and Z planes. This XYZ data is shown in 3D space and is known as a point cloud (a cloud of 3D points).
The point cloud data can be illustrated in tabular format however it is typically presented in a visual format which shows objects within a 3D space. Modern CAD programs such as AutoCAD and Revit have many tools when it comes to viewing and manipulating point cloud data.
When 3D scanning, it is typical to set up in a number of different locations taking numerous scans. This is to ensure all the data required is captured. Once off of the site, the 3D scan data has to be registered together using a program such as Faro SCENE. This accurately stitches all the scans together to form a registered point cloud. This process is very important, if the point cloud is not registered together well then there will be accuracy and dependency issues with the data.
A point cloud can be imported into a CAD program and then manipulated to show the exact data you are after. For instance, if you 3D scan a building, you could take a slice through the point cloud at 1 metre above ground level. This can then be traced to produce a very detailed floor plan drawing. Equally, you could slice the point cloud going along the Z plane to produce a sectional cut through the building.
Point cloud scanning is the future of surveying and should be considered on most projects where important spatial data is required. The level of detail a scanner can pick up is very useful and can save a considerable amount of time on-site versus traditional surveying methods.
3D Laser Scanning
A 3D laser scanner uses LIDAR (light detection and ranging) to survey objects. A typical 3D laser scanner can survey over 100,000 points a second which means a lot of data is acquired very quickly! Scanning is an excellent way of capturing a lot of detail however there are some key limitations such as scanning highly reflective objects such as glass and mirrors. These items can cause issues as the light is not properly reflected back to the scanner.
Depending on the scanner type, they can also record colour data for the point recorded which allows the point cloud to be shown in colour. This can be very useful for certain projects that require colour definition.
A 3D laser scanner will survey objects that are within its line of sight and scanning range. There is a range of different 3D scanners used for varying applications, from small sub-millimetre applications (scanning engineered parts) to large hundreds of metre scans where by you might need to scan the underside of a bridge.
Scanners pick up and produce point clouds of anything they can see, this could be:
- Light fixtures
- Walls
- Doors
- Windows
- Electrical Plugs
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