Capturing reality on the go

At Leica Geosystems, we are committed to provide the best surveying technology and shape smart change by creating products that are mobile, agile and efficient – just like the Pegasus:Backpack.

In this new Expert Insights Section, Alessandro Nuzzo, Product Line Manager for Mobile Mapping at Leica Geosystems, explains in detail the technology, workflow and applications for this wearable reality capture solution.

What is the Leica Pegasus:Backpack?

Pegasus:Backpack is a disruptive wearable tool enabling users to capture reality faster, spending less time in the field while differentiating their business model with new applications in where and how they capture reality.

Can you explain the integrated technologies of the Pegasus:Backpack?

The core technology centres on navigation. We distinguish indoor and outdoor missions. For outdoors, integrating a multiple band GNSS receiver leverages all available GNSS satellites from around the globe to achieve a high sigma confidence in terms of positioning accuracy. Furthermore, we have the Inertial Measurement Unit (IMU) consisting of three gyroscopes and three accelerometres that compensates the movements while walking and collecting data.

For indoor missions, we rely on the IMU and the LiDAR Simultaneous Localisation and Mapping (SLAM) algorithm. While scanning and creating a map, SLAM is able to detect the environment and calculate the trajectory based on LiDAR measurements. The Pegasus:Backpack provides a robust trajectory even in GNSS-denied areas.

In addition to the trajectory, we have two LiDARs collecting 600,000 points per second and five automatic exposure controlled, high dynamic cameras with 4 MPix resolution each – enabling feature extraction over LiDAR or measurements over accurate photogrammetry. All the data are stored inside an integrated multi-core industrial PC with one terabyte solid-state drive storage in order to save long missions easily.

The system is powered with four hot-swap batteries extending the four-hour operational time to any desired length by simply swapping discharged batteries with charged ones on-the-fly. This technology is housed in a carbon fibre unibody chassis that is highly ergonomic for comfortable wearing.

How did you combine Geosystems technology with Hexagon business technology to create this wearable reality capture system?

We started with a strong experience matured in Pegasus:Two, where we knew how to precisely manage GNSS and IMU data to calculate the trajectory and synchronise the LiDAR and imagery into a seamless data output. We set our target high and wanted the Pegasus:Backpack to become the first commercially wearable and indoor capable system available.

Within Hexagon, we strongly leveraged our Novatel know-how. Together, we tailored the GNSS/IMU calculations and developed our Hexagon SLAM solution. Expertise from different teams within Hexagon led us to make the right decisions.

What makes the Pegasus:Backpack special?

It is clear – the product’s disruptive characteristics. Starting from the futuristic product design to the use of carbon fibre to reduce weight and increase the ergonomic. Continuing with the embedded technology, dual LiDAR, five high dynamic cameras, IMU and SLAM navigation technology, it is a unique data collection tool for the modern surveyor.

The combination of these distinguished characteristics makes the Pegasus:Backpack extremely versatile for outdoor and indoor applications enabling customers to spend less time on the field, differentiate their business model, and stay competitive in a consolidating market.

Can you explain the workflow (data acquisition, post processing, extract information, export to CAD) of the Pegasus:Backpack?

The precondition is to have a master GNSS station within 15 kilometres from the data collection location or HxGN SmartNet coverage. No surveyor skills are required for the data collection – it can be simply done by a trained operator.

The operator turns on the system and connects the delivered tablet over Wi-Fi or LAN to the internal PC where the data acquisition module runs – this is the dashboard for data acquisition. Before starting capture, the operator needs to initialise the system, first statically, and then by walking a couples of minutes. After the position is determined, he starts data collection and has full control by the tablet, where he can monitor in real time the images, LiDAR units and GNSS signal strength. Once the mission is completed, the operator does a static end alignment phase and closes the mission.

The post processing workflow is highly automated. By simply inserting an USB Key into the Pegasus:Backpack, all data can be downloaded and is ready for post processing. Operators can pre-select the deliverables and launch the post processing calculation – there is no need to supervise the process. A powerful tool to interface with the SLAM algorithm is embedded directly within the post processing software. It enables the visualisation, and if needed, the correction of the SLAM navigation before processing and completing the dataset.

All industry standard file formats, like LAS, PTS, and E57, are supported and can be exported. Depending on the software solutions used for feature extraction, the Pegasus Software Suite natively produces 3D point clouds and images for ESRI ArcMap or Autodesk AutoCAD.

For what applications can the Pegasus:Backpack be used?

The system’s flexibility and ease of use is expanding the applications, going from the most common, for example, professional Building Information Modelling (BIM) documentation, surveying, asset collection, underground infrastructure maintenance, disaster recovery, and safety and security, to more digital reality oriented applications, like industrial training, accidents simulation and urban planning.

What are some of the most interesting applications where you’ve seen the Pegasus:Backpack used?

There are dozens of exciting applications. One of the coolest data collection was in Vars, France, where we provided 3D data for the speed world record attempt in downhill snow mountain biking.

At 3,000 m high, with strong wind, and temperatures around 0 degrees Celsius, a skier was wearing the Pegasus:Backpack and collected the necessary data to calculate a digital terrain model (DTM) that was fed into a Leica iCON controlled snow machine to prepare a perfect slope for the speed attempt.

Another very impressive application was the data collection of the Paris sewers- an extremely challenging environment for humans and the equipment. With the Pegasus:Backpack and the optional flashlight module, we collected a never-before-seen perspective – having the city surface with its buildings and streets and the sewers underground structure in one single 3D data set. The flashlight module delivered crystal clear images unveiling all the manual sprayed notes on the walls. This information was never georeferenced and not visible in any cadastral map. Through the images, it was possible to recognise where maintenance was needed to assure a continued public service avoiding unexpected outages.

What are the customers doing with the data obtained from this wearable reality capture solution?

The Pegasus:Backpack is used to provide multiple, fast and accurate data layers where traditional methods face limits in terms of feasibility, access and costs.

Various customers are using the data for urban area survey, where city centres are only accessible by walking and are closed to traffic or public transportation. An extraordinary application in India is the mapping of overcrowded urban districts. This project provided a detailed cadastral map of the thousands of unknown huts, giving to the habitants an address, name and dignity.

Electricity utility companies are collecting the high voltage power lines to map the infrastructure, analyse the cable sag between two electricity poles, and verify if vegetation is obstructing the right-of-way – assuring a high level of network service availability. Others are taking full advantage of the Pegasus:Backpack indoor capability and collecting entire buildings, verifying the as-built in terms of documentation and square metres per room. Recently, Italian civil protection used the Pegasus:Backpack to quickly get an overview and properly plan the recovery of a devastated city in Italy after an earthquake. All these data use cases have in common the advantage of multiples layers of information provided by LiDAR, imagery, and SLAM or navigation.

The Leica Pegasus:Backpack was recently featured on the BBC’s Italy’s Invisible Cities series. Can you tell us more about how the Leica Pegasus:Two and the Leica Pegasus:Backpack played a major role in revealing the secrets of these fascinating Italian cities?

It was a fantastic experience working with great professionals. The Pegasus:Backpack and Pegasus:Two were recognised for their ease of use, flexibility, speed and the quality of the data collection they provided. Similar to survey professionals, also in TV shows, production time is related to costs.

When we were in Venice capturing the canals on a boat with Pegasus:Two, within one day we collected more than 10 km of 3D point cloud and thousands of images in one single capture. We didn’t have to close scanning areas, no curious tourists disturbed the collection - we simply sailed under bridges to be able to generate a new “canal view” perspective that would have been impossible with traditional capturing methods. The flexibility, in terms of vehicle and power source independence, made the difference.

In Naples, Florence and Pisa, the challenge was different. As many historical European cities, the city centre is densely populated, closed to traffic, and palaces are obstructing the GNSS signal. In Naples, we collected underground caves, and in Florence and Pisa, we captured indoors. A technology relying only on GNSS/ IMU would not be able to collect data – with the Pegasus:Backpack, it was a home game. By using SLAM, we collected and georeferenced all our data step by step, delivering a comprehensive 3D dataset without the need of scan registrations. By just wearing the 12-kg light Pegasus:Backpack, we captured within 15 minutes the complete spiral staircase of the Pisa Tower with its 293 steps.

How is the R&D mobile mapping team preparing for new industry trends and integrating new technologies?

Technology cannot be seen only as hardware or sensor integration. Of equal importance is the related software workflow and processing speed. It is there where we will focus and decide if additional information layers are needed to develop the right answer to meet market needs– a layer of information that predicts the accuracy and helps users deliver the highest accuracy, before even leaving the office.

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