How Do 3D Laser Scanners Work?

Capturing the World Around You With 3D Laser Scanning

Since the dawn of civilisation, humans have needed to register information on their surroundings. Evidence shows that ancient Egyptians surveyed the area to build their famous pyramids around 5000 years ago. Throughout history, capturing information of spaces has allowed us to erect edifications, find new resources, regulate political territories, and prepare the land for agriculture. Nowadays, the essence remains the same. However, the demand is on a whole new scale, and our technology must be up to the task.

3D Laser scanning, along with GPS and EDM (Electronic Distance Measurement), provides the means to understand our surroundings as never before in history. Now, let’s delve into why this is a huge deal. But first, what are 3D scanners?

The 3D Scanner Technology

3D models are becoming one of the most versatile and useful pieces of data in this increasingly digitalised world. A 3D object offers many advantages when it comes to solutions. Simulation, visualisation, analysis, manufacturing, and documentation are just some examples. On the other hand, a 3D scanner enables the user to create, from a real object, a virtual replica; in other words, a digital twin.

We can describe a 3D scanning workflow in these essential steps:

1. The scanner captures point data based on XYZ coordinates and colour
2. A registration software processes the data into a final point cloud  format
3. Creating mesh formats by point connection

To capture point data, there are mainly three methods

1. Photogrammetry: By overlapping many photographs around an object, then a software application can determine coordinates via triangulation
2. Structured Light: A projector emits light patterns that deform upon reflecting from the object. Then, a camera recognises 3D geometries through those deformations. For more information on these scanners, please read this article or visit the Peel3D and Creaform pages
3. Laser: The scanner emits a laser beam that upon bouncing from the object’s surface, a sensor defines the collision distance

Now that we have a broader idea of what a 3D scanner does, let’s focus our attention on why the laser scanner is so advantageous.

Why Laser Scanners

3D Laser scanning technology, also known as LIDAR (Laser Imaging, Detection, and Ranging), is optimal for long-range measurements with dense 3D maps. Thanks to their incredibly fast spinning mirror, these systems can scan at a rate of 1 million points per second! Laser scanners are not only exceptional at scanning objects and measuring distances, but also ideal for capturing objects under movement. Indeed, this advantage enables many uses in robots, drones, terrestrial vehicles, and aerial vehicles with airborne laser scanners.

Two types of laser scanners exist on the market: Time of flight and triangulation. The main difference between each mechanism is how they measure distances. On the one hand, time of flight scanners measures the time on which the beam gets back to the receiver. On the other hand, triangulation uses angles and trigonometry. Regarding their performance, the main difference is that time of flight is better suited for long ranges, while triangulation is a better choice for precision scanning at shorter ranges. For the rest of the article, we’ll be focusing on time of flight scanners.

Area Survey Optimisation

Surveying an area can be incredibly demanding in terms of time, costs, safety and effort, not to mention error-prone results and some areas’ inaccessibility by traditional means. The holistic approach of laser scanning captures all the data needed and integrates it into an accurate digital replica of the working space.

In just a few and simple operations, a laser scanner can quickly and efficiently generate more robust information than workflows with conventional sets of tools (Theodolites, tapes, levelling rods, chains, compasses, altimeters, total stations). Production cycle times can be reduced from weeks to days.

For most applications, laser scanners work best from a stationary tripod. Moreover, you can take as many scans as you need from various locations, then you can align them to stitch together into a final point cloud. In other circumstances, where the area is too extensive or hard to reach, you can make scans from vehicles and robots.

Now, what do we do with the data at hand? Well, you now have an accurate replica that you can open as a file from a computer to make all the measurements and observations you need, limitlessly. Furthermore, you can generate CAD data, 2D floorplans, VR environments, and even integrate it into a BIM (Building Information Modelling) ecosystem.

Applications

Some applications where laser scanners provide massive benefits are:

• Construction: Failure inspection, remodelling, urban planning, capturing BIM data
• Terrain surveys: Topographies, farming, natural resource analysis, forestry
• Heritage documentation and archaeological investigation
• Public safety: Forensics (Documentation of crime scenes), law enforcement
• Others: 3D printing, arts, gaming, VR

3D Laser Scanners vs Other Technologies

We haven’t fully answered the initial question yet: Why laser scanners? Let’s make a brief comparison with other technologies to get more insight.

First, structured light. Structured light scanners are ideal for reverse engineering applications, where capturing features with micrometrical precision is needed while tight tolerances are required. Still, unlike laser scanners, it falls short for large scale applications and tightly lit outdoor environments.

In comparison, photogrammetry can deliver exceptionally reliable and accurate results, regardless of range (Indoors or outdoors). However, it strongly relies on many factors like camera resolutions, heavy post-processing power, illumination settings, textured surfaces, and, most importantly, very skilled and experienced users. If you’re looking for a more efficient, faster, cost-saving process, with fewer errors, real-time monitoring of results and a faster learning curve, laser scanning is the obvious choice.

Laser scanners are, without a doubt, potent tools but the bad news are that they can be very expensive, reaching prices of over 100 thousand GBP. Thankfully, as technology develops, more accessible alternatives are joining the market.

Leica BLK360 Scanner: Powerful and Affordable

Leica Geosystems, a leading company with 200 years of experience in surveying technologies, developed a more accessible alternative to their higher-end laser scanners: The Leica BLK360 model. But don’t let the appearance of this little device fool you, the Leica BLK360 scanner remains one of the most powerful laser scanners in the market. We’ll show you why in the following sections:

Scanning Quality vs Price

The Leica BLK360 offers just enough performance for effective solutions on the industrial level; the following are the key features:

• High accuracy (4mm @ 10m, 7mm @ 20m)
• 3 resolution settings (5/10/20 mm @ 10m)
• Range: Up to 60m
• Scan rate: 360000 points per second
• Spherical images (360° horizontally, 300° vertically)
• High-speed scanning: <3 min @ mid resolution, dome capturing
• 15Mpxl 3 camera system
• High Dynamic Range (HDR) imaging
• Thermal camera

If this performance satisfies your requirements, there’s no need to overinvest in higher-end scanners like the ScanStation P50/P40/P30 and the RTC360 models, which are 4 to 6 times more expensive than the BLK360.

Portability and Ease of Use

Besides its performance, the Leica BLK360 is one of the lightest and smallest scanners on the market (H: 165mm, D: 100mm, W: 1kg), making it easy to move around and install. Moreover, it is straightforward to use, doesn’t require a steep learning curve, and most of its processes are automatic. With just pressing one button, this scanner is capable of doing quick 360 captures.

Additionally, it comes with an IMU sensor for automatic tilt measurements and a better understanding of its position in relation to its environment. As a result, having the coordinate system of every scan consistently aligned with each other smoothens the registration process.

The BLK360 offers automatic registration and scan alignment, but you might need to take extra steps in some situations. Some problematic surfaces, like those that are shiny or matte dark, undistinguishable features, and repetitive patterns, can produce noise and make the registration process harder. Adding targets as references is a good practice to stitch point coordinates together accurately.

The following videos briefly clarify some of the best practices for this scanner.

Software & Connectivity

Lastly, we can’t leave the article without taking a peek at the BLK360’s software offerings.

For point cloud registering and editing, Cyclone REGISTER 360 and Cyclone REGISTER 360 (BLK Edition) are easy to use and made specially to optimise your workflows.

Additionally, the Cyclone FIELD 360 app enables remote operation and real-time feedback into your mobile devices via WIFI connection. This app allows you to visualise your scanning operations’ performance, make measurements, and leave annotations.

If you want to learn more about 3D laser scanning or if you’re looking to make the best choice on which 3D scanner is the most suited for you, SolidPrint3D is here to help you. For more information, please call SolidPrint3D on 01926 333 777 or email on info@solidprint3d.co.uk.