With mobile mapping technology readily available, anyone can effortlessly map the world around them. For newcomers to surveying, this tech breakthrough removes the dependency on trained experts – but it does require the mapper to have a basic understanding of a point cloud. What is it, how is it created and how is it used? In our latest education blog, we look at the top point cloud questions and provide all the information you need to get started.
Here at GeoSLAM we get super excited about point clouds and hope you will too. Point clouds are now faster, easier and more accessible than ever before. If you’re interested in mapping but aren’t trained in point cloud software – this blog is for you!
1. What is a point cloud? What measurements are included in a point cloud?
A point cloud is essentially a huge collection of tiny individual points plotted in 3D space. It’s made up of a multitude of points captured using a 3D laser scanner. If you’re scanning a building for example, each virtual point would represent a real point on the wall, window, stairway, metalwork etc.
The scanner automatically combines the vertical and horizontal angles created by the laser beam to calculate a 3D XYZ coordinate position for each point to produce a set of 3D coordinate measurements which often includes its colour value stored in RGB (more on that in question 6) and intensity. These details can then be transformed into a digital 3D model that gives you an accurate detailed picture of your object.
The denser the points, the more detailed the representation, which allows smaller features and texture details to be more clearly and precisely defined. So, if you were to zoom in on a point cloud of The Tower of London, you’d see tiny points creating the whole.
A forestry point cloud captured with a ZEB Horizon and viewed in GeoSLAM Hub (coloured by elevation)
2. How do you create a point cloud?
Firstly, scan your object with an easy-to-use 3D laser scanner such as a ZEB Revo RT. You might find that some objects need multiple scans from different viewpoints which are then combined in the software later. This is because a 3D scanner can only record data points for the surface within the scanner’s line of sight and the object may need to be passed twice to capture the entirety of its geometry and reduce occlusions (gaps in data).
Next, remove the USB memory stick and plug it into your computer. A 3D scanning software such as GeoSLAM Hub will render the points from the raw data in real-time to give you a complete point cloud to represent your object in 3D space. Simple!
3. How long does it take to create a point cloud?
It all depends on how many scans are needed and what exactly needs scanning. Or whether you’re using traditional stationary scanning equipment or a mobile laser scanner which would considerably reduce scanning time. However, for example, a 130-scan point cloud dataset (which is A LOT of data) of an office building including all the individual rooms, corridors and service areas could take nearly 25 hours to process.
Those scans may have only taken a day to collect with a mobile scanner, but manual involvement in processing means that the registration of that point cloud dataset can take around 3 days to carry out, and potentially longer if manual correction is necessary. Smaller datasets can be processed in hours.
With a device like the ZEB Revo RT a pointcloud is created in real-time and you can see the live visualisation progress with the attached tablet. It requires no processing other than extracting data from the device, so you can have a full pointcloud in a matter of minutes – depending on what’s being scanned.
Screenshot from the ZEB Revo RT showing a scan in real time, including the orange trajectory line
4. Do you need to be trained in point cloud software to create a point cloud?
Geo-SLAM’s Hub software is specifically designed for ease-of-use. By completing minimum online training, you will be able to process raw point cloud data by directly transforming it into BIM (Building Information Modelling). Its menu is easy to understand and the tools and functions let you navigate your way through the cloud easily and efficiently.
4. What is the perspective on a point cloud?
Since a point cloud is a fully 3D format, you can view it from any perspective, no matter what device was used to capture it. You can capture a point cloud on foot using a handheld 3D laser scanner such as a ZEB Horizon, and then view it from the top down as if you’re seeing the scanned environment from a drone. In fact, you can view any part of the point cloud, including objects and rooms, from any angle as required. Pretty cool huh?
5. Can a point cloud be created in colour – how?
When you look at a colourised point cloud of a room, you’re seeing both the dimensional measurements and the RGB value (stands for “Red Green Blue”, the standard method of producing colours that this colourisation makes the point cloud look more like a 3D photograph, which helps images on screens), of that room at each point where the scanner measured. The effect is users (both new and experienced) to understand quickly and easily what they’re looking at. Cloud colour can simply be added via your chosen format.
ZEB Discovery colourised data
6. How do you put multiple point clouds together?
Handheld 3D laser scanners are efficient enough that many spaces can be captured in a single scan. However, larger projects such as a large sports arena or campus may require more scans for complete coverage, which means you’ll have a number of point clouds that you’ll need to merge into one final point cloud for the whole asset. A variety of software applications enable you to do this. However, if you use a GeoSLAM laser scanner, it makes good sense to use GeoSLAM’s complimentary Hub software, which means you won’t have any problems importing and processing your raw data. Within Hub you can merge multiple pointclouds together.
8. What are the best point cloud formats to use?
Different scanners produce raw data in multiple formats, and each piece of software has different exporting capabilities. Output formats are also determined by what data is required and who needs it. If you wanted to store the data away for a long period, you’ll probably be best storing the point cloud as an ASCII file. Other popular formats are LAS, PTS, PTX, XYZ and Fast Binary.
9. What is a pointcloud used for?
It’s a brilliant and non-intrusive way to accurately measure object properties in 3D. For example, sites such as care homes, stadiums and museums don’t have to be shut down in order to be measured. The measurements are also far more detailed than anything traditional survey equipment can produce.
A BIM model of a housing complex in Vietnam, captured with a ZEB Revo and modelled in Revit
In the architecture industry which uses As-Built models; point cloud software eliminates time-consuming and costly revisits to the site and allows an architect to visualise and convey new concepts. Point cloud has become the new standard for all design industries as it provides an instant virtual model to test ideas with. They are also used to create 3D CAD (computer-aided design) models for manufactured parts, for metrology and quality inspection, and for a multitude of visualisation, animation, rendering and mass customisation applications.
We hope this gets you out the blocks and you quickly become a point cloud enthusiast. Creating point clouds is both easy and simple – and anyone can do it. We hope you have fun creating yours!
Looking for some inspiration on taking your point cloud to new places, check this out.