How Drones Help Sensat Digitize the World

Recently, Waypoint sat down with Romain Kirchhoff, Head of Operations at Sensat, to talk about their use of drone technology to help with its mission of digitizing the world. Romain has an MSc in Management, Technology and Entrepreneurship from the Ecole polytechnique fédérale de Lausanne (EPFL) and the Hong Kong University of Science and Technology (HKUST).

romain-kirchhoff-sensat
Hi Romain, thank you for chatting with us today. Can you give us an overview of Sensat?

Sensat is a startup working to digitize the physical world. Essentially, the real world is offline; it cannot connect with computers or other devices. This is a huge hurdle when developing Artificial Intelligence for real-world use, something that we believe can help us to live our lives more sustainably.

We do this by creating digital twins, or digital representations of real-world locations. We then infuse real time data sets from a variety of sources. The result is an accurate, digital and up to date copy of the real world in a machine-readable format. Drones are an important part of this process, as we use a mixture of drone imagery and LiDAR data (laser scanner) to generate highly accurate digital replicas for our clients in Infrastructure and AEC.

We have an incredible team based in London and recently raised $10 million for our Series A which was led by Tencent!

Has Sensat always used drone technology to create these digitizations, or have you tried other methods?

As a young startup, we started with drone technology—and that’s all we started with. We have learned how to achieve high levels of detail in our photogrammetry, but there is always a tradeoff between detail and the area coverage.

We are now extending that photogrammetry knowledge and expertise into terrestrial laser scans, UAV LiDAR, plane photogrammetry, plane LiDAR, and satellite photogrammetry.

Thanks to the drone industry, we have been able to create our company.
So, Sensat avoided traditional methods from the beginning and chose to use drone technology instead. What challenges came with those methods that fueled the decision to use drones?

We did investigate traditional methods; looking at things like terrestrial scans, as well as aerial scans using a plane or helicopter.  We found that terrestrial scans couldn’t provide the large-area coverage we needed, and that helicopters could not provide enough detail compared to ground-based surveys. They’re also expensive and weather-permitting.

Drones unlocked the middle ground between those two methods, providing the accuracy and coverage we needed to work within the infrastructure sector.

drones-digitize-rail-development
Sensat created a highly accurate digital replica of the UK's largest rail development project: a 16km2 site.
Which drone models did you originally assess and what made you decide to go with senseFly?

We’ve used senseFly fixed-wing drones since the beginning, but we also used quadcopters. Through our three-year journey, we have assessed many different quadcopters and fixed-wing drones, even a few VTOLs. When assessing a drone provider and model to operate, the deciding factor we focus on the most is reliability.

We’re thankful for senseFly because we know that their drones are the most reliable on the market. That’s been crucial from a safety perspective and for generating consistent, high quality data.

Which senseFly models do you fly?

We started with the eBee RTK. Then, the eBee Plus. Most recently, we acquired two eBee X’s which have been fantastic. We’re also very happy with the quality of the senseFly S.O.D.A. 3D sensor. It’s great because it has a gimbal that ensures all images are perfectly nadir. The option to have oblique images is also a key differentiator  for mapping areas with complex structures such as cities.

One of the key things that’s helped us adopt and implement drone technology are our people internally.
Can you walk us through a typical workflow for a project?

We are using a mix of capture methods ranging from terrestrial scanning to satellite imagery.

If we select the drone as the capture method for a specific project, we will follow a general workflow:
Step one is to assess all relevant risks and mitigate against them until we and the client are satisfied with the mitigation in place.
Step two is to go on site and capture the imagery. The main focus is on safety and we have integrated several features to ‘see and be seen’ by other airspace users and local authorities.
Step three is to generate a single 2D map and a 3D model from these pictures. The Quality Assessment of the raw images and the outputs is another key step to ensure we provide the best data to our clients.

The final output and file format will be tailored to the client needs which can range from earthwork calculation and progress monitoring to 3D topographic CAD and BIM.

Finally, instead of delivering a 15GB LAS file that the client can’t even open in their construction software, like Autodesk (it will crash); we deliver the 3D model and 2D map in our intuitive environment Mapp accessible online to visualize and interact with the datasets. While simple 2D and 3D measurements or annotations are available on Mapp, the client can also crop an area of interest and open it in their own software. We can also ‘augment’ the digital twin by integrating BIM designs or live feeds into Mapp such as IoT sensors, CCTV cameras, and so on.

What post-processing software do you use?

We use different processing software like Agisoft, Pix4D or ContextCapture. We’re always testing different technology to make sure we’re using the best processing software out there.

Drones unlocked the middle ground between [traditional aerial and terrestrial] methods, providing the accuracy and coverage we needed to work within the infrastructure sector.
In your opinion, what are the business benefits to using drones?

If we compare drones to terrestrial surveys, the benefits of using drones is that they’re more efficient and safer – you don’t need to have boots on the ground when surveying a highway for example.

If we compare drones to traditional aerial surveys like planes or helicopters, we are usually more accurate because we are closer to the object but that depends on many factors like which camera we use and the flight altitude for example. We are also generally cheaper and using drones is more environmentally friendly.

drones-digitize-HS2
Sensat mapped the entire Phase One route (180 km) of the proposed HS2 rail line from London to Birmingham to create a fully digital simulation.
So, how accurate is your data collection using senseFly drones?

The absolute accuracy we achieve with drone photogrammetry is dependent on many factors including the Ground Sampling Distance (GSD). In general, our GSD is 25 millimeters and our absolute accuracy is within 50 millimeters in the horizontal plane (X and Y), and 75 millimeters in the Z axis. Those numbers are specific to our general operations when we use a 20-megapixel camera like the S.O.D.A 3D, at a 108 meters altitude above ground level, which means that each pixel is 25 millimeters wide.

This level of accuracy is a perfect fit for our large-scale survey. It provides a good enough accuracy while having a manageable file size for the end client. For smaller surveys we can get sub-centimeter accuracy if required by using more advanced and expensive hardware.

Is it fair to say drones have positively impacted your business?

Impacted is not the right word. Thanks to the drone industry, we have been able to create our company.  That was a massive win for us because it has helped us enter this new market between traditional terrestrial and aerial scanning. It’s provided us the ability to deliver projects to early adopters within the industry. When I look around me, I can tell you we have achieved some great milestones with drones, and it is only the beginning!

drones-digitize-cambridge
Sensat has digitized several cities in the United Kingdom, including Cambridge (above).
What are some challenges you face when using drones?

Most of the challenges we’ve had have been on the regulatory side. Because it’s a new technology that’s evolving so rapidly, regulations are still changing and improving. It’s not like passing your driving license and you are free to drive anywhere in the world.

We have been pushing the envelope by collaborating with the government’s Pathfinder program and flying beyond visual line of sight to assess what can be achieved while maintaining a high level of safety.

Another challenge is the weather. Coming from Switzerland, the UK is a little bit… different. For example, in one day, you can have a clear blue sky, then some thunderstorms!

We need to have an understanding of the weather to assess when we’ll have the next clear window on a specific location to plan our operations accordingly.

One other challenge would be the takeoff locations. With fixed-wing drones, you need a larger area to be able to take off and land which can be a scarce resource depending on the survey location.

We’re thankful for senseFly because we know that their drones are the most reliable on the market. That’s been crucial from a safety perspective and for generating consistent, high quality data.
Was it difficult to convince clients to understand why you chose to use drone technology at Sensat?

I think there are two sides. On the client side, I think we’re lucky to have people who are looking at innovation within the infrastructure industry. Our first clients were willing to take risks and test drone surveys with us. With our track record, we are now tackling more complex projects such as national infrastructure projects worth multi-billions.

The other is our side and the fact that we are lucky to be working with people who are passionate and driven about our vision. One of the key things that’s helped us adopt and implement drone technology are our people internally.  They will do whatever it takes and will always look for the next thing to bring us closer to our vision. We can improve the data captured, try different techniques and always strive to come up with the best outcomes for our clients. Thanks to our team and their talent, we’re able to improve our knowledge of drone technology and become what we are now.

sensat-ops-team-field
Part of Sensat's Data Operations team.
What’s next!? Are you working on any interesting projects?

We are working on a wide array of projects at the moment including highways, railways, housing development and even airports! We are also working on our range of capture method to deliver the highest quality possible.

Unfortunately, I can’t talk too much about it at the moment but be sure to stay tuned, it is just the beginning!

Thank you so much for chatting with us today, Romain!

You’re very welcome.

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Comments (1)

Drones have made surveying quite easy. It helped us to survey land, water, even the air pressures. Digitizing the world was a great step and drones have made it more quick and easier. Thank you very much for explaining the importance of drones. I would like to know more about deep water surveys.
Deep water survey

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