LiDAR… Today’s Technology

Watch out!” my colleague Harry shouted as a distracted driver blew through our lane closure, racing toward the two of us and our array of survey equipment.

We were standing on the side of the Lougheed Highway in Coquitlam, BC, on a cool, misty evening in 2008. Harry had flown out from Ontario to lead a laserscanning campaign along the Trans Canada Highway. The firm I worked with at the time, MMM Group, had the contract to complete an as-built survey of the highway and connecting roads, as part of the design for a new bridge over the Fraser River.

Harry was our resident laserscanning expert, a technology I knew very little about and had never used before. My education and work experience was in traditional survey methods, such as total stations and satellite positioning. Those methods result in a single point to identify a feature in the physical world. The point would have an X, Y, Z coordinate and description, like Edge of Pavement. We would measure many points as part of a topographic survey, creating a sample of the environment we were tasked with measuring.

For the large infrastructure project, however, we were utilizing a Leica Scan Station 2, a terrestrial laser scanner capable of measuring 50,000 points per second. At the time, it was a technological marvel, capable of quickly and accurately measuring the features surrounding it. Rather than taking a small sample of points and interpolating between, our scan data produced thousands or millions of points on the surface of an object, enabling structures like concrete abutments or steel bridge components to be modelled in 3D. Those 3D models allowed engineers to accurately and confidently design a new bridge and corresponding road network.

Thankfully that distracted driver on the Lougheed narrowly missed Harry and me. We walked away shaken, with a new level of respect for traffic-control people who spend their working hours next to speeding vehicles. Completing that project also left me with a fascination with how lasers can be used to measure and model the physical world. Over the next 15 years I would continue to grow in my knowledge and use of laser scanning, also known as LiDAR.

LiDAR is an acronym for Light Detection and Ranging. In simple terms, a LiDAR sensor emits a laser beam that reflects off objects and returns to the sensor. Since we know how fast a laser beam travels (the speed of light), we can calculate the location of objects by measuring how long it takes the laser beam to return to the sensor. The calculations happen almost instantaneously while the sensor is being operated. The resulting information is compiled in a point cloud—a cluster of thousands or millions of points representing the area scanned by the LiDAR sensor.

The first commercial LiDAR applications were developed in the late 1980s when the US Department of Defense launched the Global Positioning System (GPS). Today GPS sensors are everywhere but satellite positioning technology was revolutionary in the ‘80s. Some very smart people figured out that a LiDAR sensor could be mounted in an aircraft and by utilizing a combination of GPS and an inertial measurement unit (IMU), the three dimensional location of the sensor could be determined, while the aircraft was in flight.

To learn more about the early days of LiDAR acquisition, I reached out to Doug Linwood, production manager at Eagle Mapping. Eagle Mapping provides aerial LiDAR and imagery acquisition and processing, among other services. While their head office is located in Langley, British Columbia, Eagle Mapping works throughout North, Central, and South America. Doug was kind enough to answer a few questions about his experience and knowledge in LiDAR.

1. In the early days of your career, what problems were solved or solutions provided, by utilizing LiDAR?

“Previous to LiDAR, mapping was either compiled by Ground Methods, Aerial Imagery, or Satellite Imagery.

• Ground methods for surface modeling are very accurate, but not efficient for difficult areas to access or large areas to cover.

• Aerial Imagery is slower than LiDAR for general surface modelling and has difficulty determining ground heights where there is vegetation.

• Satellite Imagery has the same issues as Aerial Imagery.

“LiDAR is faster in terms of processing and is more accurate for determining ground elevations and other features than from Imagery (Aerial or Satellite). Where the ground cannot be seen in vegetated areas from imagery, LiDAR can penetrate through vegetation to the ground because the LiDAR pulses will find enough openings in the vegetation to reach the ground.

“The use of LiDAR also provides feature information such as the shape of a roof or other above-ground features on the same flyover as for the ground. Processing can be a bit of work to classify all those features, but LiDAR is much faster than previous methods of mapping for that purpose.” survey acquisition was done by a subcontractor. Owning aircraft now required management and maintenance of the plane as well as hiring new personnel for the field division and training them. Additionally, we had to deal with equipment that worked fine in testing, but now thousands of kilometres from nowhere, could fail or malfunction. Over time, with experience, we have become very good at solving those issues.

“Processing the data had its own challenges; people had to be trained and it takes years to be proficient. The hardware required to process large LiDAR projects is significant and several projects happening at once has also required quite powerful computer systems. I believe we have become quite efficient at the processing and am proud of the quality of data we deliver.”

3. How has the use of LiDAR within your industry changed over the course of your career?

2. What challenges did you have to overcome in utilizing LiDAR data?

“Integrating LiDAR into our workflow at Eagle Mapping involved adding a whole new technology. There was the learning curve of acquisition, beginning with starting up a 'field' division.

“Previous to LiDAR, all our work was from the office, and any photo, satellite. or ground

“From a mapping perspective, LiDAR was initially used to determine surface models. As sensors became more efficient and powerful, we could collect much larger areas in the same time it used to take to fly smaller areas, or pick up a higher density in one flyover. Clients are now using LiDAR to determine tree species and identify geological formations. LiDAR is being used for object recognition and recording feature locations such as powerline transformers if the density is high enough. We have flown projects in Central America to determine where historic buildings such as old temples are located. Prior to LiDAR, those locations were never known. LiDAR is also used in safety applications to identify hazards. Using LiDAR the aviation industry identifies above-ground objects at airports for possible issues.

“Terrestrial LiDAR (laser scanning) has now been around for a few years and is an emerging market being used for all sorts of applications. Laser scanning can be used for building design. New builds in houses and commercial buildings are recording Mechanical, Electrical, Plumbing (MEP) locations so once the walls are up, future renovations will know exactly where those items are behind the walls. Terrestrial LiDAR is being used inside buildings to model the exact building dimensions. Laser scanning can be used for future planning or a record of what was there if needed. That is known as Building Information Modeling (BIM).

“Bathymetric LiDAR sensors are available to measure below the surface of water, although the water needs to be reasonably clear; that type of LiDAR is limited to depth depending on the turbidity of the water.”

As Doug alluded, some 30 plus years after mounting LiDAR in aircraft, the modern-day applications are almost endless. LiDAR is becoming part of the day-to-day vocabulary through its depiction in film and television or through the inclusion of LiDAR sensors in new technology, like smartphones, vehicles, and military applications.

In addition to finding LiDAR in commercial and military products, laser scanning is becoming increasing commonplace in the technology sector. Surveyors, engineers, and other professionals are realizing the benefits of utilizing LiDAR within their industry. LiDAR sensors are becoming smaller and less expensive and can now be mounted to drones (UAVs), on top of vehicles, and even built-in to small, handheld platforms.

The laser scanning tools are a great means of obtaining vast amounts of data. But like any technological advancement, the widespread adoption of LiDAR is not without its challenges. One challenge with using LiDAR is assessing the quality of the data. The latest iPad or iPhone may have a LiDAR sensor in it, but is the data any good? What is the accuracy of the data? Or put differently, what is a reasonable use for the technology? performing as expected and the products being produced meet the required standards. Through the past century, land surveyors have incorporated all kinds of technology into their toolkits, including Electronic Distance Measuring (EDM), Global Navigation Satellite Systems (GNSS), photogrammetry, and more recently laser scanning. There is a time and a place for each piece of technology and land surveyors have the expertise to ensure the correct tool is being used for the task at hand.

Another challenge that comes with LiDAR is managing the data. Today’s laser scanners are capable of measuring up to 2 million points per second—even a short scan campaign can result in many gigabytes of data. Processing the data requires a workstation with significant computing abilities and storing the data requires the ability to archive terabytes of data. Surveyors and other geospatial professionals have the required abilities, but the average person doesn’t have the means of accessing and visualizing the vast datasets. Dr. Derek Jacoby is not one of those people.

The survey industry is well positioned to help other professionals understand the abilities and limitations of laser scanning. Land surveyors have always checked and assessed their data to ensure their equipment is

Jacoby is a Research Manager in Computer Science in the Faculty of Engineering at the University of Victoria. As I understand it, a technology called Neural Radiance Fields (NeRF) utilizes multiple 2D images to generate what is called a 3D scene. In other words, a NeRF is used to render a digital, 3D environment from photos. In addition to the digital rendering, one of the benefits of a NeRF is the potential for compression of the large datasets, making them more manageable and more accessible.

The research at the University is taking the emerging technology and pushing the envelope even further. Specifically, Jacoby is looking at how LiDAR can be used to generate a scene, since LiDAR can be a much more efficient data collection tool than 2D imagery. Additionally, his team is studying how generative Artificial Intelligence (AI) can be used in representing spatial data in a digital scene. Or in simple terms, using intelligent software to create digital, 3D environments.

The concept of AI-generated NeRFs offers a glimpse into the future and how some of new technologies may impact our lives. One can imagine a scenario where LiDAR sensors are everywhere— built into vehicles, embedded in our handheld devices, and mounted on infrastructure. The sensors would be continuously collecting data and then uploading that data through 5G connectivity. Artificial Intelligence would use the data to build, update, and verify 3D models of the real world. That digital data would be continuously uploaded to autonomous vehicles and plugged in to the navigation system, ensuring the passengers have a safe ride home. Or perhaps the data is the foundation of a virtual city, enabling virtual tourism, digital property inspections for real estate transactions, or asset management of the city’s infrastructure. Those are just interesting hypothetical scenarios, but wherever the future of LiDAR takes us, I am comforted that industry experts like Doug Linwood and academics like Derek Jacoby are at the bow of the ship, scanning the horizon for new opportunities and new applications. We’re in good hands. ▲

Jordan Litke, P.Surv, BCLS, is an Associate with Polaris Land Surveying Inc., based in Victoria, BC.

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