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The Year of LiDAR

2022 is clearly the year of LiDAR. 

At all of the UAS shows in the USA, Mexico, Canada, and EU, the hot topic is LiDAR in 2022, and 2023 is ramping up to be more of the same, with significant growth.

LiDAR is a “LIght Detection And Ranging” sensor, utilizing a laser, position-controlled mirror, an IMU (Inertial Measurement Unit) and internal processing to record geolocation data. 

A LiDAR sensor emits a pulse of light towards the target (ground) The light is reflected from the surface/earth (a point) and returned to the sensor. The receiver detects the returning signal and calculates the distance the light has traveled. Using the position of the sensor, mirror, IMU, the direction in which the light was sent and the distance calculated. Following this return and calculations, the 3D position where the signal was returned may be determined. With millions of reflections striking a terrestrial surface and returning to the LiDAR sensor, these contact “points” are used to generate the 3D model or ortho re-creating the target area in a digital environment.

Because LiDAR sensors generate their own signal pulse, illumination from other sources  (for example, the sun), many LiDAR operator/pilots capture data at night. As long as there is nothing interfering between sensor and surface it is therefore possible to collect data below cloud cover (or in the dark). LiDAR can offer extremely flexible access to areas requiring scans, given the ability to fly at night, or when cloud cover has a negative impact on a site where photogrammetry may not be possible due to lighting conditions. 

LiDAR sensors were previously relegated to fixed wing or rotary aircraft due to weight and cost, now accessible by any mid or heavy-lift UAS. 

The profile seen here, demonstrates the penetration capabilities of the Microdrones HR VLP16 payload. Note the greater resolution of data below trees, both broadleaf and palm. 
The above image is the author’s first experience with LiDAR; a Velodyne VLP16 with Geodetics IMU, mounted to a Yuneec H920 hexcopter.

With ever-increasing flight efficiency coupled with reduced weight and cost of LiDAR sensors, there are several aircraft and LiDAR systems available at affordable price points to suit virtually any budget. While LiDAR may not yet be for casual pilots, commercial pilots report near-immediate full ROI with LiDAR due to the current scarcity of complete systems. 

Sensors may be purchased as a complete/total solution with aircraft, support software, and payload, or owners of medium lift systems may purchase LiDAR sensors separately to mount on whatever aircraft they’re familiar and comfortable with.   For example, there are many LiDAR payloads available for the DJI Matrice 300 platform, Inspired Flight, Freefly, Yuneec, Maptek, Microdrones, and other systems.

LiDAR packages may be stand-alone, combined with separate RGB cameras for photogrammetry, or assembled with both in one housing. For example, the highly popular GeoCue 515 package not only offers a Hesai XT32 LiDAR sensor, it also includes two 20MP RGB cameras for colorizing the pointcloud, or for photogrammetry deliverables. Additionally, the system is designed for properly and precisely scaling RGB data on to the 3D pointcloud, providing not only a very accurate and precise model, but colorized, photo-realistic data for engineers, surveyors, construction teams, graphic designers, game designers, etc. 

Pilots, engineers, program managers, surveyors will want to consider several factors when choosing a LiDAR payload for purchase or rent.

  • Cost
  • Penetration
  • Resolution
  • Software cost/flexibility
  • Difficulty of operation

Different sensors will yield different results. Below are examples from the DJI L1, the Velodyne VLP16 (Microdrones HR), Hesai Pandar XT32 , and the Reigl Vux1 sensors. Profiles/cross sections captured from LP360 illustrate the surface data from the various sensors, and is a confident method of displaying vegetation penetration. 

DJI L1

Pictured above, the DJI L1 is incapable of any effective penetration through vegetation or other porous areas. Additionally, strip alignment may be challenging in some scenarios. This data was captured, initially processed in DJI Terra, and finish processed in GeoCue LP360

Microdrones MD1000HR (VLP16)

The profile seen here, demonstrates the penetration capabilities of the Microdrones HR VLP16 payload. Note the greater resolution of data below trees, both broadleaf and palm.

GeoCue 515

In this image, there are no gaps beneath the trees. In the center, a uniform depression is visible. The Hesai Pandar XT32 was able to “see” below shallow water surface. In this case, approximately 12” of water depth, yet the creek bottom is solid (visible). While the below-water data is not viable for measurement, it does provide greater data for engineering considerations. 

REIGL VUX1

These two illustrations are sourced from the Riegl Vux1 sensor. This sensor provides the highest resolution of all four images compared here, with a much higher price tag to match the image quality. Note in the zoomed in profile, train rails/tracks are not only visible, but accurately measurable. There are no holes in the surface beneath any of the trees, and the tree detail is enough to classify tree types.
 

“Penetrating vegetation is a key function of LiDAR sensors; this is why tree profiles/slices have been used to illustrate these challenging scenarios.”

WHAT ABOUT SOLID STATE LiDAR SYSTEMS?

It is worth noting that solid state LiDAR systems are on the rise, and very much in development for longer-range with high density. Technology hasn’t improved to a point where solid state LiDAR might be broadly applicable for UAS work, while the technology has proved promising due to lighter weight, less power consumption, and speed. However, development is heavily focused on autonomous vehicles at present, yet it is fully anticipated we’ll soon see solid state LiDAR available for aerial applications.

HOW IS LiDAR DIFFERENT FROM PHOTOGRAMMETRY?

Photogrammetry uses multiple images with embedded geodata, matching pixels, and data information to create an orthomosiac. Pointclouds can be derived from images with slightly less accuracy, but a significant time commitment.  A 50 acre field processed as a pointcloud derived from photos may take up to 12 hours on an average computer, while the same computer will process the LiDAR-sourced pointcloud in under 30 minutes.  LiDAR is significantly faster to fly than UAS designed for photogrammetry, as the need for deep overlap is lessened in LiDAR workflow. 

Additionally, LiDAR may be flown at night (unless colorization is needed) while photogrammetry requires daylight hours. 

On the other hand, photogrammetry missions may be flown while there is water on the ground after a flood or heavy precipitation. LiDAR works best in dry, non-reflective environments.  Mirrored windows, water reflecting on leaves, ponds, creeks, etc will display as blacked-out areas in a LiDAR scan.

In this scan of the Colorado River, areas containing water display as black.

Not all software applications are compatible with all the different LiDAR sensors. The way trajectories are read/displayed, how data is managed/handled, even basic features are very different between the various software tools available today. For example, until recently, the data from DJI’s L1 LiDAR system could only be initially processed in DJI Terra software, which is quite limited, and many feel is “kludgy and slow.”  It’s also not a platform known for being stable. 

Recently, GeoCue has added the DJI L1 to it’s compatibility platform, enabling DJI users to use the LP360 software with L1 data, with great stability, flexibility, and speed.

SOFTWARE

When choosing a LiDAR system, there are many considerations, the greatest of which is how important high resolution and precision at ground will be to projects/workflows. Budget frequently makes this determination. However, bottom line vs long-term needs are often at odds with each other; it’s wise to spend “up” to a higher grade LiDAR sensor when customer satisfaction is at the top of the list.  Research often requires higher grade sensors as well.

When choosing a LiDAR system, consider the aircraft carrying the payload, the software required to process the data, and consider flight times as well. Two hours flying a narrow beam sensor vs 30 minutes of a wider throw may make all the difference, particularly when the company has a deep backlog and is focused on efficiency.

Whether LiDAR an organization is ready for LiDAR now, or down the road, there has never been a better time to learn more about LiDAR, pointclouds, and the differences of data processing from photogrammetry workflows. 

Special thanks to Brady Reisch of KukerRanken for the profile slices of data.

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A Deep Insider’s Look at a Rugged Terrain Mission to Investigate a Helicopter Crash with Drones

A Deep Insider’s Look at a Rugged Terrain Mission to Investigate a Helicopter Crash with Drones

Crash site investigation with drones has emerged as a leading application for unmanned systems in public safety.  Gathering data that can be used by investigators in a courtroom, however, requires careful mission planning.  Here, sUAS expert and industry figure Douglas Spotted Eagle of  KukerRanken provides a detailed insider’s view of a helicopter crash site investigation.

Unmanned aircraft have become proven assets during investigations, offering not only the ability to reconstruct a scene. When a high ground sampling distance (GSD) is used, the data may be deeply examined, allowing investigators to find evidence that may have not been seen for various reasons during a site walk-through.

Recently, David Martel, Brady Reisch and I were called upon to assist in multiple investigations where debris was scattered over a large area, and investigators could not safely traverse the areas where high speed impacts may have spread evidence over large rocky, uneven areas. In this particular case, a EuroStar 350  aircraft may have experienced a cable wrap around the tail rotor and boom, potentially pulling the tail boom toward the nose of the aircraft, causing a high speed rotation of the hull prior to impact. Debris was spread over a relatively contained area, with some evidence unfound.

crash site investigation with drones

Per the FAA investigators;

“The helicopter was on its right side in mountainous densely forested desert terrain at an elevation of 6,741 ft mean sea level (MSL). The steel long line cable impacted the main rotor blades and was also entangled in the separated tail rotor. The tail rotor with one blade attached was 21 ft. from the main wreckage. Approximately 30 ft. of long line and one tail rotor blade were not located. The vertical stabilizer was 365 ft. from the main wreckage.”

With a missing tail rotor blade and the missing long line, unmanned aircraft were called in to provide a high resolution map of the rugged area/terrain, in hopes of locating the missing parts that may or may not aid in the crash investigation.

The terrain was difficult and unimproved, requiring four-wheel drive vehicles for access into the crash site. Due to rising terrain, we elected to launch/land the aircraft from the highest point relevant to the crash search area, which encompassed a total of approximately 70 acres.

Adding to the difficulty of finding missing parts was that the helicopter was partially covered in grey vinyl wrap, along with red and black vinyl wrap, having recently been wrapped for a trade show where the helicopter was displayed.

drones in crash site investigation

We arrived on scene armed with pre-loaded Google Earth overheads, and an idea of optimal locations to place seven Hoodman GCP discs, which would allow us to capture RTK points for accuracy, and Manual Tie Points once the images were loaded into Pix4D.  We pre-planned the flight for an extremely high ground sampling distance (GSD) average of .4cm per pixel. Due to the mountainous terrain, this GSD would vary from the top to the bottom of the site. We planned to capture the impact location at various GSD for best image evaluation, averaging as tight as .2cmppx. Some of these images would be discarded for the final output, and used only for purposes of investigation.

Although the overall GSD was greater than necessary, the goal is to be able to zoom in very deep on heavily covered areas with the ability to determine the difference between rocks and potential evidence, enabling investigators to view the overall scene via a 3.5 GB GeoTiff in Google Earth, and refer back to the Pix4DMapper project once rendered/assembled.

The same scene minus initial marker points.

Although working directly in Pix4D provides the best in-depth view of each individual photo, the Google Earth overlay/geotiff enables a reasonably deep examination.

Using two of the recently released Autel EVO II Pro aircraft, we planned the missions so that one aircraft would manage North/South corridors while the other captured East/West corridors.  Planning the mission in this manner allows for half the work time, while capturing the entire scene. This is the same method we used to capture the MGM festival grounds following the One October shooting in Las Vegas, Nevada. The primary difference is in the overall size, with the Pioche mission being nearly 70 acres, while the Las Vegas festival ground shooting area is under 20 acres in total.

Similar to the Las Vegas shooting scene, shadow distortion/scene corruption was a concern; flying two aircraft beginning at 11:00 a.m. and flying until 1:30 aided in avoiding issues with shadow.

Temporal and spatial offsets were employed to ensure that the EVO II Pro aircraft could not possibly collide, we set off at opposite sides of the area, at different points in time, with a few feet of vertical offset added in for an additional cushion of air between the EVO II. We programmed the missions to fly at a lower speed of 11 mph/16fps to ensure that the high GSD/low altitude images would be crisp and clean. It is possible to fly faster and complete the mission sooner, yet with the 3 hour travel time from Las Vegas to the crash site, we wanted to ensure everything was captured at its best possible resolution with no blur, streak, or otherwise challenged imagery. Overall, each aircraft emptied five batteries, with our batteries set to exchange notification at 30%.

Total mission running time was slightly over 2.5 hours per aircraft, with additional manual flight over the scene of impact requiring another 45 minutes of flight time to capture deep detail. We also captured imagery facing the telecommunications tower at the top of the mountain for line of sight reference, and images facing the last known landing area, again for visual reference to potential lines of sight.

crash site investigation with drones

By launching/landing from the highest point in the area to be mapped, we were able to avoid any signal loss across the heavily wooded area. To ensure VLOS was maintained at all times, FoxFury D3060’s were mounted and in strobing mode for both sets of missions (The FoxFury lighting kit is included with the Autel EVO II Pro and EVO II Dual Rugged Bundle kits).

Once an initial flight to check exposure/camera settings was performed, along with standard controllability checks and other pre-flight tasks, we sent the aircraft on their way.

Capturing over 6000 images, we checked image quality periodically to ensure consistency. Once the missions were complete, we drove to the site of impact to capture obliques of the specific area in order to create a more dense model/map of the actual impact site. We also manually flew a ravine running parallel to the point of impact to determine if any additional debris was found (we did find several small pieces of fuselage, tools assumed to be cast off at impact, and other debris.

The initial pointcloud took approximately 12 hours to render, generating a high-quality, highly dense initial cloud.

crash site investigation with drones

After laying in point controls, marking scale constraints as a check, and re-optimized the project in Pix4D, the second step was rendered to create the dense point cloud. We were stunned at the quality of the dense point cloud, given the large area.

The dense point cloud is ideal for purposes of measuring. Although this sort of site would typically benefit (visually) from texturing/placing the mesh, it was not necessary due to the high number of points and deep detail the combination of Pix4D and Autel EVO II Pro provided. This allowed us to select specific points where we believed points of evidence may be located, bringing up the high resolution images relevant to that area. Investigators were able to deep-dive into the area and locate small parts, none of which were relevant to better understanding the cause of the crash.

“The project generated 38,426,205 2D points and 13,712,897 3D points from a combination of nearly 7,000 images.”

crash site investigation with drones

Using this method of reviewing the site allows investigators to see more deeply, with ability to repeatedly examine areas, identify patterns from an overhead view, and safely search for additional evidence that may not be accessible by vehicle or foot. Literally every inch of the site may be gone over.

crash site investigation with drones

Further, using a variety of computer-aided search tools, investigators may plug in an application to search for specific color parameters. For example, much of the fuselage is red in color, allowing investigators to search for a specific range of red colors. Pieces of fuselage as small as 1” were discovered using this method. Bright white allowed for finding some items, while 0-16 level black allowed for finding other small objects such as stickers, toolbox, and oil cans.

Using a tool such as the DTResearch 301 to capture the RTK geolocation information, we also use the DTResearch ruggedized tablet as a localized pointcloud scan which may be tied into the Pix4Dmapper application. Capturing local scan data from a terrestrial perspective with GCP’s in the image allow for extremely deep detail in small environments. This is particularly valuable for construction sites or interior scans, along with uses for OIS, etc.

Primary Considerations When Capturing a Scene Twin

  • GSD.​ This is critical. There is a balance between altitude and propwash, with all necessary safety considerations.
    Vertical surfaces. In the event of an OIS where walls have been impacted, the ability to fly vertical surfaces and capture them with a consistent GSD will go a long way to creating a proper model. Shadow distortion.​ If the scene is very large, time will naturally fly by and so will the sun. In some conditions, it’s difficult to know the difference between burn marks and shadows. A bit of experience and experimentation will help manage this challenge.
  • Exposure.​ Checking exposure prior to the mission is very important, particularly if an application like Pix4Dreact isn’t available for rapid mapping to check the data on-site.
    Angle of sun/time of day​. Of course, accidents, incidents, crime, and other scenes happen when they happen. However, if the scene allows for capture in the midday hours, grab the opportunity and be grateful. This is specifically the reason that our team developed night-time CSI/Datacapture, now copied by several training organizations across the country over recent years.
  • Overcapture.​ Too much overlap is significantly preferable to undercapture. Ortho and modeling software love images.
  • Obliques. ​Capture obliques whenever possible. Regardless of intended use, capture the angular views of a scene. When possible, combine with ground-level terrestrial imaging. Sometimes this may be best accomplished by walking the scene perimeter with the UA, capturing as the aircraft is walked. We recommend removing props in these situations to ensure everyone’s safety.

What happens when these points are put aside?

This is a capture of a scene brought to us for “repair,” as the pilot didn’t know what he didn’t know. Although we were able to pull a bit of a scene, the overexposure, too-high altitude/low GSD, and lack of obliques made this scene significantly less valuable than it might have been.

Not understanding the proper role or application of the UA in the capture process, the UA pilot created a scene that is difficult to accurately measure, lacking appropriate detail, and the overexposure creates difficulties laying in the mesh. While this scene is somewhat preserved as a twin, there is much detail missing where the equipment had the necessary specifications and components to capture a terrific twin. Pilot error cannot be fixed. Operating on the “FORD” principle, understanding that ​FO​cus, exposu​R​e, and ​D​istance (GSD) cannot be rectified/compensated for in post processing means it has to be captured properly the first time. The above scene can’t be properly brought to life due to gross pilot error.

“ALWAYS PUT THE AIRCRAFT OVER THE PRIMARY SCENE LOCATION TO CONFIRM EXPOSURE SETTINGS, KEEPING ISO AS LOW AS POSSIBLE. USE ISO 50-100 IN MOST OUTDOOR SCENARIOS TO OBTAIN THE BEST IMAGE. NEVER USE OVERSATURATED PHOTO SETTINGS OR LOG FORMATS FOR MAPPING.”

Ultimately, the primary responsibility is to go beyond a digital twin of the scene, but instead offer deep value to the investigator(s) which may enhance or accelerate their investigations. Regardless of whether it’s a crash scene, insurance capture, energy audit, or other mapping activity, understanding how to set up the mission, fly, process, and export the mission is paramount.

Capturing these sorts of scenes are not for the average run n’ gun 107 certificate holder. Although newer pilots may feel they are all things to all endeavors benefitting from UA, planning, strategy, and experience all play a role in ensuring qualified and quality captures occur. Pilots wanting to get into mapping should find themselves practicing with photogrammetry tools and flying the most challenging environments they can find in order to be best prepared for environmental, temporal, and spatial challenges that may accompany an accident scene. Discovery breeds experience when it’s cold and batteries expire faster, satellite challenges in an RTK or PPK environment, planning for overheated tablets/devices, managing long flight times on multi-battery missions, or when winds force a crabbing mission vs a head/tailwind mission. Learning to maintain GSD in wild terrain, or conducting operations amidst outside forces that influence the success or failure of a mission only comes through practice over time. Having a solid, tried and true risk mitigation/SMS program is crucial to success.

We were pleased to close out this highly successful mission, and be capable of delivering a 3.5 GB geotiff for overlay on Google Earth, while also being able to export the project for investigators to view at actual ground height, saving time, providing a safety net in rugged terrain, and a digital record/twin of the crash scene that may be used until the accident investigation is closed.

EQUIPMENT USED

●  2X Autel EVOII™ Pro aircraft

●  Autel Mission Planner software

●  FoxFury D3060 lighting

●  DTResearch 301 RTK tablet

●  Seko field mast/legs

●  Seko RTK antenna

●  Hoodman GCP

●  Hoodman Hoods

●  Manfrotto Tripod

●  Dot3D Windows 10 software

●  Pix4DMapper software

●  Luminar 4 software

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Experts Tested 4 Different Drone Mapping Solutions for Crime Scene Investigation

Experts Tested 4 Different Drone Mapping Solutions for Crime Scene Investigation. Here’s What Happened.

At Commercial UAV Expo in Las Vegas, more than 300 drone industry professionals watched as experts tested four different drone mapping solutions for crime scene investigation at night.

Guest post by Douglas Spotted Eagle, Chief Strategy Officer at KukerRanken

Commercial UAV Expo brought UAS professionals, developers, manufacturers, first responders, and related industries under one roof for the first time in nearly two years. Due to the pandemic, the show was less attended than previous years, yet provided robust live demonstrations, night flight, daytime seminars, panels, and case studies for the relatively large audience. There was a strong buzz amongst the crowd about being at an in-person event, and experiencing face to face communication for the first time in many months.

In addition to the “Beyond the Cage” Live Drone Demo Day that launched Commercial UAV 2021, produced by Sundance Media Group, Wednesday night provided attendees with a glimpse of the Crime Scene Investigator tools function in the dark hours. Sundance Media Group developed this methodology several years ago at the request of a law enforcement agency and has been presenting this methodology at academies, colleges, universities, and tradeshows since 2017, with a variety of aircraft including DJI Mavic, Phantom 4, Yuneec H520, Skydio, and Autel EVO series (versions 1 and 2). All successfully output data, excepting Skydio, which struggles with brightly lit events in surrounding darkness.

Presented by FoxFury, Sundance Media Group, Autel, and Pix4D, this event also invited SkyeBrowse to participate in the demonstration, showing the effectiveness and speed of their application.

Testing Drone Mapping Solutions for Crime Scene Investigation: Setting the Scene

With a model covered in moulage, mock slit throat, and blood trail on the ground, the demonstration began with the multi-vendor team led by Brady Reisch, Bryan Worthen of Kuker-Ranken, Todd Henderson and Patrick Harris of SMG,  and David Martel.  The team  placed four FoxFury T56 lighting systems at specific, measured points in the scene, supplemented by FoxFury NOW  lanterns and Rugo lighting to fill in holes and eliminate shadows.

Douglas Spotted Eagle of SMG and KukerRanken emcee’d the event through the two flights.

Douglas Spotted Eagle addresses the crowd of 300 persons

SkyeBrowse had the first flight, with its one-button capture. Brady Reisch set up the mission, with input from the SkyeBrowse developer instructing the exposure levels of the camera for the SkyeBrowse video mission. Once the mission was completed, the photos were uploaded to the SkyeBrowse website, where results were found approximately 30 minutes following the flight.

Brady Reisch of KukerRanken sets up the Skybrowse mission with Bobby Ouyang of Skybrowse

The Autel EVO II Pro was programmed on-site for an automated Skybrowse mission and the demonstration began. The area is highly congested with palm trees and buildings enclosing the small rotunda in front of the Mirage Hotel Convention Center.

Brady Reisch flew the second EVO II  mission manually, in much the same configuration as though the aircraft had flown a double-grid mission, supplemented by high-altitude orbit, coupled with manually captured orbit and select placements. Because of the crowd, time was a consideration. In an actual homicide scene, more low-placed images would have been captured.

Brady Reisch monitors time as Pix4DReact rapid-renders the scene (60 seconds)

The mission photos were uploaded to Pix4dReact on-scene and rendered while the audience observed, requiring approximately 60 seconds to output an ortho-rectified, 2D image, complete with evidence markers/tags, and PDF supplemental report output. Also loaded were the photo images into Pix4D and Leica Infinity software packages, to be rendered for 3D viewing once the show floor opened on Thursday. Pix4DReact is a two-dimensional, rapid-mapping solution, so there is no 3D view.

The four screen captures tell the rest of the story, and readers can determine for themselves what each software is capable of providing.  One point of interest is that there were many claims of “guaranteed 1cm of precision regardless of flight area,” which has yet to be verified. The Kuker-Ranken team will be re-flying a mission with two separate GPS systems (Leica and Emlid) to verify the claims of precision.

Precision is Repeatable

Precision is repeatable. Accuracy is the degree of closeness to true value. Precision is the degree to which an instrument or process will repeat the same value. In other words, accuracy is the degree of veracity while precision is the degree of reproducibility. With a base station, NTRIP, Spydernet, PPK, or RTK workflow, precision is always the goal, well-beyond accuracy. This is a relatively new discussion in the use of unmanned aircraft, and although the topic seems simple enough, complexity holds challenges not easily dismissed by inexperience or lacking education and practice.  We are fortunate to have a partner in Kuker-Ranken, providing precision tools to the survey, forensic, civil engineering, and AEC industries since 1928. The KR team includes PLS’, EIT, and other accredited precision professionals, rarely found in the UAS industry.

Precision is critical for surveyors, civil engineers, forensic analysts and investigators, construction sites, mapping, agriculture, and other verticals in the UAS industry, and this sort of scene is no exception. Being able to properly place a map or model into a coordinate is necessary for many professional pilots in the UAV field, and while this mission is not precise to coordinate, it is precise within itself, or in other words, measurements will be accurate in the image, while being imprecise to the overall location.

We’ll dive more deeply into precision in a future article. For purposes of this exercise, we’re more interested in accuracy of content in the scene, and all four outputs were similar in accuracy within the scene itself. In other words, distances, volumes, and angles may be measured point to point. Pix4DReact is not as accurate as the other three tools, as it’s not intended to be a deeply accurate application given speed of output.

Output Results of Drone Mapping Solutions

Output #1: SkyeBrowse (processing time, approximately 35 minutes)

Output #2: Pix4Dreact (processing time, approximately 1 minute)

drone mapping solution Pix4Dreact

Output #3: Pix4Dmapper (processing time, approximately 2.5 hours)

drone mapping solutions Pix4Dmapper

Output #4: Leica Infinity (processing time, approximately 2 hours, 50 minutes)

drone mapping solutions Leica Infinity

Agencies who would like access to this data are invited to contact Brady Reisch, VDC Specialist at Kuker-Ranken.

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Selecting the Right Drone for Your Construction Business

Selecting the Right Drone for Your Construction Business

Douglas Spotted Eagle and Brady Reisch headed into the field to collect aerial construction data over fourteen weeks with three different drones.  Their goal was to determine which drone was best for the construction job site.

They used three popular aircraft for the comparisons and the results were pretty surprising.   

Drones Compared:

Unmanned Aircraft (UA/Drones) have rapidly become a significant component of the modern construction industry workflow whether it’s for progress reporting, site planning, BIM, inventory control, safety awareness, structure inspection, topo’s, or other purposes. Site supervisors, architects, and stakeholders all benefit from the rapid output of accurate 2D/Ortho, or 3D models that may be used for purposes ranging from simple visualizations, progress reporting, stockpile calculations, DSM, contours, to more complex overlaying blue-prints in the As-Designed/As-Built or BIM process.

Choosing the right aerial asset/UA may be challenging, particularly as the marketing of many UA is focused on RTK built in (rarely accurate) PPK solutions and a many component workflow versus others that are single-step workflows. Decisions on aircraft choices will be made based on budget, accuracy requirements, speed to result, and overall reporting requirements.

On any site flown for BIM, input to AutoDesk or similar tools, having accurate ground control points (GCP) is required. GCP’s may be obtained from the site surveyor, county plat, or other official sources, and this is often the best method assuming that the ground control points may be identified via UA flight-captured images. Site supervisors may also capture their own points using common survey tools. Devices such as the DTResearch 301 RTK tablet may be used to augment accuracy, combining GPC location points from the air and on the ground. Failing these methods, site supervisors can capture their own points based on the specific needs of the site. These points may be calculated via traditional rover/base RTK systems, or using PPK, RTK, or PPP solutions, again being budget and time dependent. If centimeter (vs decimeter) accuracy is required, RTK or PPK are necessary.

Putting accuracy aside, image quality is gaining importance as stakeholders have become accustomed to photo-grade ortho or models. Oftentimes, these models are used to share growth with inspectors as well, which means having presentation-grade images may be critical. Image quality is high priority when generating pre-development topos, or simply illustrating a tract of land from all directions. In other words, a high-quality imaging sensor (camera) is a necessity. Some aircraft allow user-choice cameras, while many UA manufacturers are creating cameras specific to their aircraft design.

Turning to aircraft, we chose three popular aircraft for the comparisons:

Flying the site several times in various conditions, the same RTK capture points are used in all three mapping projects. The DTResearch 301 RTK system is used to capture GCP on-location, with Hoodman GCP kit as the on-ground GCP. The Hoodman SkyRuler system was also captured as a scale-constraint checkpoint.

This commercial site is small in size (1.64 acres), and one we were able to begin capturing prior to forms being laid, all the way to vertical installation.

Accuracy varied greatly with each aircraft system, particularly in elevation calculations. Deviations are from projected points vs the GCP points obtained through a surveyor’s RTK system.
Overall (and to our surprise), the Autel EVO was most accurate with a deviation of:

  • x-5.112ft
  • y-47.827ft
  • z-16.541ft 

The Yuneec H520/E90 combo was not far behind with a deviation of:

  • X-10.323ft
  • y-44.225ft
  • z-92.788ft

Finally, the DJI Phantom 4 presented deviations of:

  • x-1.95ft
  • y-45.565ft
  • z-140.626ft 

All of these deviations are calculated and compensated for in Pix4DMapper, which is used to assemble all of these week-to-week projects.
As 3D modelling was part of the comparison/goal, obliques were flown in addition to nadir captures. While manual settings are often essential for high quality maps and models, in the following images cameras were all set to automatic exposure, shutter, ISO.

It is important to remember that these are NOT corrected via network nor base station. This is autonomous flight, localized in Pix4D.

MODELS

AUTEL EVO (Original version)
YUNEEC H520/E90
PHANTOM 4 PRO

All aircraft models work well with Pix4DMapper, although at the time of this writing, Pix4D has not created lens profiles for the Autel EVO (they have indicated this feature should be available “soon”). We custom-sized the lens profile ourselves, based on information provided by Autel’s product managers. *as of 2.1.22, Pix4D has generated lens profiles for both Autel EVO and EVO II aircraft.

Orthos

AUTEL EVO
YUNEEC H520/E90
PHANTOM 4 PRO

Although image quality is subjective, our client and our team all agree the Autel EVO provides the best image quality and color of all aircraft, with all aircraft set to automatic exposure, shutters peed, and ISO of 100. This is a surprise, given the Autel is a ½.3 imager, vs the 1” rolling shutter of Yuneec and global shutter of the DJI aircraft. Based on internet forums, Autel is very well known for their camera parameters being impressive.

All flights are single-battery flights. This is important, as changing batteries offers different functions for the various aircraft. Using Yuneec and DJI products and their respective software applications, we are able to fly larger sites with proper battery management with the aircraft returning to launch point when a battery is depleted and resume a mission where it left off once a fresh/charged battery is inserted. The Autel mission planner currently does not support multi-battery missions (although we’re told it will soon do so).

There are a few aspects to this workflow that are appreciated and some that are not. For example, when flying Autel and Yuneec products, we’re able to act as responsible pilots operating under our area wide Class B authorization provided by the FAA. To fly the DJI Phantom, the aircraft requires a DJI-provided unlock that permits flights. It’s a small annoyance, yet if one shows up on a jobsite not anticipating an unlock, it can be tedious. In some instances, we are just on the edge and outside controlled airspace, yet DJI’s extremely conservative system still requires an unlock. Most times, the unlock is very fast; other times, it doesn’t happen at all.

All three aircraft are reasonably fast to deploy, and this is important when a LAANC request for a zero-altitude grid is a short window. Autel clearly wins the prize for rapid deployment, with the EVO taking approximately 30 seconds to launch from case-open to in-the-air. Mission planning may be managed prior to flight and uploaded once the UA has left the ground. We are experiencing much the same with the latest release of the EVO II 1” camera as well. We also appreciated the lack of drift and angle in relatively high winds (26mph+).

DJI is next fastest at approximately three minutes, (assuming propellers remain attached in the case), while the mission planning aspect is a bit slower than the Autel system. DJI uploads the mission to the aircraft prior to launch. Of course, this is assuming we’ve already achieved an approval from DJI to fly in the restricted airspace, on top of the FAA blanket approval. If we don’t, we may find (and have found) ourselves unable to fly once on-site, due to glitches or slow response from DJI.

Yuneec is the slowest to deploy, given six props that must be detached for transport. Powering the ST16 Controller, attaching props, and waiting for GPS lock often requires up to five minutes. The mission planning tool (DataPilot) is significantly more robust than DJI’s GSPro, third party Litchi or other planning apps, and is far more robust than Autel Explorer’s mission planner. DataPilot also essentially ensures the mission will fly correctly, as it auto-sets the camera angle for different types of flight, reducing the margin for pilot error. The Yuneec H520 is superior in high winds, holding accurate position in reasonably high winds nearing 30mph.

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All three aircraft turn out very usable models. All aircraft capture very usable, high-quality images. All of the aircraft are, within reason, accurate to ground points prior to being tied to GCP.

We were surprised to find we prefer the Autel EVO and are now completing this project after having acquired an Autel EVO II Pro with a 1” camera and 6K video.

Why?

Foremost, the Autel EVO family offered the most accurate positioning compared to the other aircraft in the many, many missions flown over this site. With dozens of comparison datasets, the Autel also offered the fastest deployment, and ability to fly well in high winds when necessary. The cost of the Autel EVO and EVO II Pro make this an exceptionally accessible tool and entirely reliable. That the Autel EVO requires no authorization from an overseas company, particularly in areas where we already have authorizations from the FAA, is significant to us, and the image quality is superior to either of the other aircraft.

We also greatly appreciate the small size of the aircraft, as it takes little space in our work truck, and our clients appreciate that we’re not invasive when working residential areas for them. The aircraft isn’t nearly as noisy as other aircraft, resulting in fewer people paying attention to the UA on the jobsite. The bright orange color, coupled with our FoxFury D3060 light kit (used even in daylight) assists in being able to see the aircraft quite easily, even when up against a white sky or dark building background.

We also of course, appreciate the speed in deployment. With safety checks, LAANC authorizations, planning a mission, and powering on remote and aircraft, the Autel EVO is deployable in under two minutes. When flying in G airspace, from case to airborne can be accomplished in under 30 seconds.

Battery life on the EVO 1 is substantial at 25 minutes, while our newly acquired EVO II Pro offers 40 minutes of flight time with incredible images to feed into Pix4D or other post-flight analytics software.

Of greatest importance, the EVO provides the most accurate XYZ location in-flight compared to the other aircraft. For those not using GPS systems such as the DTResearch 301 that we’re using on this project, accuracy is critical, and being able to ensure clean capture with accurate metadata is the key to successful mapping for input to Autocad applications.

WHERE TO LEARN MORE:

www.autel.com (UA, mission planning)

www.dtresearch.com (RTK Tablet with hyper-accurate antenna system)

www.dji.com (UA, mission planning)

www.foxfury.com (Lighting system for visualization)

www.hoodman.com (GCP, LaunchPad, SkyRuler)

www.Pix4D.com (Post-flight mapping/modelling software)

www.sundancemediagroup.com (training for mapping, Pix4D, public safety forensic capture)

www.yuneec.com/commercial (UA, mission planning)

With thanks to Autel, Hoodman, DTResearch, and Pix4D.

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Part 91, 101, 103, 105, 107, 137: WHAT’S THE DIFFERENCE?

All these FARs, what’s a drone pilot to do in order to understand them? Do they matter?

YES!

In virtually every aviation pursuit except for sUAS, an understanding of regulations is requisite and part of most testing mechanisms.  As a result, many sUAS pilots holding 

a Remote Pilot Certificate under Part §107 are woefully uninformed, to the detriment of the industry.

Therefore, sUAS pilots would be well-served to inform themselves of how each section of relevant FARs regulate components of aviation.

Let’s start by digging into the intent of each Part.

  • §Part 91 regulates General Operating and Flight Rules.
  • §Part 101 regulates Moored Balloons, Kites, Amateur Rockets, Unmanned Free Balloons, and some types of Model Aircraft.
  • §Public Law Section 336 regulates hobby drones as an addendum to Part 101.
  • §Part 103 regulates Ultra-Light Vehicles, or manned, unpowered aviation.
  • §Part 105 regulates Skydiving.
  • §Part 107 regulates sUAS
  • §Part 137 regulates agricultural aircraft

RELEVANT PARTS (Chapters):

Part §91

This portion of the FARs is barely recognized, although certain sections of Part 91 may come into play in the event of an action by the FAA against an sUAS pilot. For example, the most concerning portion of Part 91 is  91.13, or “Careless or Reckless Operation.” Nearly every action taken against sUAS pilots have included a charge of 91.13 in the past (prior to 107).

Specific to drone actions, The vast majority of individuals charged have also included the specific of a 91.13 charge.

sUAS pilots whether recreational or commercial pilots may be charged with a §91.13 or the more relevant §107.23 (reckless)

It’s pretty simple; if there are consequences to a pilot’s choices and actions, it’s likely those consequences also included a disregard for safety or planning, ergo; careless/reckless. The FAA has recently initiated actions against Masih Mozayan for flying his aircraft near a helicopter and taking no avoidance action. They’ve also taken action against Vyacheslav Tantashov for his actions that resulted in damage to a military helicopter (without seeing the actual action, it’s a reasonable assumption that the action will be a §91.13 or a §107.23 (hazardous operation).

Other parts of Part 91 are relevant as well. For example;

  • §91.1   Applicability.

(a) Except as provided in paragraphs (b), (c), (e), and (f) of this section and §§91.701 and 91.703, this part prescribes rules governing the operation of aircraft within the United States, including the waters within 3 nautical miles of the U.S. coast.

The above paragraph includes sUAS.  Additionally, Part 107 does not exclude Part 91. Airmen (including sUAS pilots) should be aware of the freedoms and restrictions granted in Part 91.

§91.3   Responsibility and authority of the pilot in command.

(a) The pilot in command of an aircraft is directly responsible for, and is the final authority as to, the operation of that aircraft.

(b) In an in-flight emergency requiring immediate action, the pilot in command may deviate from any rule of this part to the extent required to meet that emergency.

(c) Each pilot in command who deviates from a rule under paragraph (b) of this section shall, upon the request of the Administrator, send a written report of that deviation to the Administrator.

§91.7   Civil aircraft airworthiness.

(a) No person may operate a civil aircraft unless it is in an airworthy condition.

(b) The pilot in command of a civil aircraft is responsible for determining whether that aircraft is in condition for safe flight. The pilot in command shall discontinue the flight when unairworthy mechanical, electrical, or structural conditions occur.

§91.15   Dropping objects.

No pilot in command of a civil aircraft may allow any object to be dropped from that aircraft in flight that creates a hazard to persons or property. However, this section does not prohibit the dropping of any object if reasonable precautions are taken to avoid injury or damage to persons or property.

§91.17   Alcohol or drugs.

(a) No person may act or attempt to act as a crewmember of a civil aircraft—

(1) Within 8 hours after the consumption of any alcoholic beverage;

(2) While under the influence of alcohol;

(3) While using any drug that affects the person’s faculties in any way contrary to safety; or

Sound familiar?

SubPart B also carries relevant information/regulation with regard to operation in controlled airspace, operations in areas under TFR ((§91.133), operations in disaster/hazard areas, flights during national events, lighting (§91.209)

PART 101

Part §101 has a few applicable sections.

Subpart (a) under §101.1 restricts model aircraft and tethered aircraft (balloons). Although subpart (a.4. iiv) is applicable to balloon tethers, there is argument that it also applies to sUAS. Subpart (a.5.iii) defines recreational flight for sUAS/model aircraft.

Finally, §101.7 re-emphasizes §91.15 with regard to dropping objects (may not be performed without taking precautions to prevent injury or damage to persons or property).  Public Law 112-95 Section 336 (which may be folded into a “107 lite” version), clarifies sections not added to Part 101.

Bear in mind that unless the pilot follows the rules and guidelines of a NCBO such as the AMA, AND the requirements of that NCBO are met, the flight requirements default to Part 107 requirements.

PART §103

Part §103 regulates Ultralight vehicles (Non powered, manned aviation)

Although no component of Part §103 specifically regulates UAV, it’s a good read as Part 103 contains components of regulation found in Part 107.

PART §105

Part §105 regulates Skydiving.

Part §105 carries no specific regulation to sUAS, an understanding of Part 105 provides great insight to components of Part 107. Part 107 has very few “new” components; most of its components are clipped out of other FAR sections.

PART §107

Although many sUAS pilots “have their 107,” very few have actually absorbed the FAR beyond a rapid read-through. Without a thorough understanding of the FAR, it’s difficult to comprehend the foundation of many rules.

PART §137

Part 137 applies specifically to spraying crops via aerial vehicles.

Those looking into crop spraying via sUAS should be familiar with Part 137, particularly with the limitations on who can fly, where they can fly, and how crops may be sprayed.
One area every ag drone pilot should look at is §137.35 §137.55 regarding limitations and business licenses.

The bottom line is that the more informed a pilot is, the better pilot they can be.  While there are many online experts purporting deep knowledge of aviation regulations and how they specifically apply to sUAS, very few are familiar with the regulations in specific, and even less informed as to how those regulations are interpreted and enforced by ASI’s. We’ve even had Part 61 pilots insist that the FSDO is a “who” and not a “what/where.” Even fewer are aware of an ASI and how they relate to the world of sUAS.

FSIM Volume 16

It is reasonably safe to say that most sUAS pilots are entirely unaware of the Flight Standards Information Management System, aka “FSIMS.” I’ve yet to run across a 107 pilot familiar with the FSIMS, and recently was vehemently informed that “there is nothing beyond FAR Part 107 relative to sUAS. Au contraire…

Familiarity with the FSIMS may enlighten sUAS operator/pilots in how the FAA examines, investigates, and enforces relevant FARs.

Chapter 1 Sections 1, 2  and 4 are a brief, but important read, as is Chapter 2, Section 2.

Chapter 3 Section 1 is informational for those looking to apply for their RPC Part 107 Certificate.

Chapter 4 Sections 2, 5, 7, 8 are of particular value for commercial pilots operating under Part 107.

Volume 17, although related only to manned aviation, also has components related to 107, and should be read through (Chapters 3 & 4) by 107 pilots who want to be informed.

Gaining new information is always beneficial, and even better if the new information is implemented in your workflow and program. Become informed, be the best pilot you can be, and encourage others to recognize the value in being a true professional, informed and aware.

 

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Six ways drones have proven themselves as a tool for the AEC, Surveying, and mapping industries.

Drones and unmanned aircraft in AEC scanning and construction

Six ways drones have proven themselves as a tool for the AEC, Surveying, and mapping industries

Drones and unmanned aircraft in AEC scanning and construction process are becoming more common.  Unmanned aircraft, or drones are becoming much more common on today’s project sites. many companies in the AEC, Surveying and mapping industries are utilizing these aircraft daily. So how do drones capture data? What are professionals getting out of said data? What makes a drone into a valuable tool versus a toy?

UAS technology has advanced to a point where the aircraft; while still very sophisticated, are quite simple to operate. They utilize; altimeter’s, magnetometers, inertial measurement units, GNSS (GPS) and radio transmitters to control the flight operations, but the end-user would never know it. These sensors and more are all managed behind the scenes so well that an operator can takeoff from any point, fly a “mission” which involves several tasks collecting data, avoid collisions from unexpected obstacles, know when they have just enough battery to return home safely and land all in a constantly changing environment, 100% autonomously starting from a single tap for initiation. Flying a drone is fun but unless you’re collecting data it brings no value. There are many sensors that can be attached to unmanned aircraft such as LiDAR and Gravitometers but in this article we are primarily going to address cameras and their use in Photogrammetry.

Photogrammetry

When you photograph an object from two different angles and add some Trigonometry, three dimensional measurements can be calculated.  The entire process is simple and automated.  A 3D model from aerial imagery is nothing new. Photogrammetry can be summarized as; the art, science and technology of making precise measurements from photos, and has been around since the mid 1800’s.

The whole process works like this: The distance (f) from a Camera Lens to its sensor is proportional to the distance (h) from said camera lens to objects being photographed. This property is written into several equations that photogrammetrists use to calculate things such as the scale of a photo and even the elevation of specific points or pixels in aerial photographs.

When two overlapping photographs are in correct orientation relative to each other, a Stereopair or Stereoscopic Imagery exists.  This imagery creates perspective on objects within the overlap of the photographs and is the principle behind all forms of 3D viewing.

Stereoscopic Imagery drones and unmanned aircraft in AEC scanning and construction

As mentioned above, drone users can pre-program routes to fly over their intended mapping area. Photos are taken with specific overlap which is computed based on altitude, speed, and the resolution of their camera sensor. Drones use the onboard sensors like GNSS or even real time corrected positioning (RTK) to both georeference the photos taken, control the flight of the by changing the RPM’s of the individual motors. This data is all carried over in the image files where they are further processed.

Today’s Photogrammetry softwares use these mathematical principles to orient, scale and combine photographs and data. The software will ultimately generate Point Clouds, Orthorectified (measurable) photos and 3D models with varying output types.

Project Output drones and unmanned aircraft in AEC scanning and construction

Drones and unmanned aircraft in AEC and Construction:  Valuable Applications for AEC, Surveying, and mapping.

Surveying and Mapping. The use of drones and unmanned vehicles in surveying and mapping is almost self-evident. Surveyors and Cartographers have used Aerial Photography dating back about as far as the invention of the airplane. What may not be immediately apparent are the costs to purchase a survey-quality UAS and required software is a small investment in comparison to traditions surveying equipment and the man hours saved easily pays for itself.   Point Clouds and Orthometric photos are great for drafting planimetric features and generating TIN surfaces to represent topography. Whether you’re mapping for design data, a feasibility study, GIS, or performing an ALTA/ACSM survey, using unmanned vehicle to capture data may be significantly more efficient than traditional means.

Reality Capture, which is just that; capturing the reality of the current conditions of a project site. This is a great practice for design, bidding, marketing and simply helping clients “capture the vision.” This may be as simple as viewing an oblique photograph or as complicated as combining a designed structure with a 3D mesh and viewing it in VR. I personally get a kick whenever I see a IFC model inserted in a point cloud.

Building Information modeling (BIM). It would be hard to mention reality capture without mentioning BIM. While flying a drone indoors is doable its not very practical so this is not what we are referring to here. Many companies today, especially in the design-build world are utilizing BIM for much more than building modeling. They are integrating models in all their civil design as well.  These departments are already using laser scanning and are familiar with point clouds so adding a UAS into their tool chest is a natural move. Drones are great for capturing data that can be used for clash detection, QC, and as-built drawings.

Pre-Construction and Takeoffs are a major part of heavy civil construction. When it comes to moving dirt, knowing exactly what must be done can make all the difference in winning a bid, making a profit or losing your shorts. This is done when companies are bidding on projects, but the same process occurs over often in design builds and any time a RFI or change order comes up. Capturing data to that represent the existing site condition is key when building a model and matching existing roadway and other civil tie-in points. Using a drone is a great way to make this happen.

Project Output2 drones and unmanned aircraft in AEC scanning and construction

Project Management. Unmanned Aircraft may be utilized for many processes in project management. Creating progress reports and viewing current conditions may be the most basic use and might just be the most beneficial when it comes to decision making. Billing on some projects is solely based on materials moved and/or installed. This makes tracking linear feet, area, and volumes the bottom line. Some other overlooked uses may include, creating safety plans and incident reports, public involvement, and training. There are also various other project management uses above.

Inspections. Drones are one of the best tools utilized in inspections. Often an environment is not safe for a person such as inspecting a high wall in an open pit mine; or the situation may not be as efficient for an individual such as climbing versus flying to inspect bolts on a suspension bridge. When we apply the use of Infrared /thermals sensors to unmanned aircraft they are capably much more. Infrared light is absorbed by water making it possible to discover moisture that may be invisible to the naked eye. This is great for leak detection among other things. Thermal makes it possible to view and analyze heat signatures. This is often used to find areas of heat loss in anything from mechanical to thermal applications.

One of the biggest challenges today’s companies in the AEC, Surveying and Mapping industry face is a shortage of manpower. The only way to overcome a shortage in manpower is to innovate. Many choosing to innovate are looking to drone to solve their problems. Two trends I’ve noticed in helping companies develop their UAS applications is that they may start with a particular expectation in mind and one drone, but they always utilize their UAS data more than they anticipated and want to expand their drone fleet. I believe UAS technology is one of the best investments for a company in these industries to make. It is very apparent to me that Unmanned Aircraft are a major focus in developing technology. They are a powerful tool and not a toy.

By Bryan Worthen Kuker-Ranken SLC

Examples:
https://cloud.pix4d.com/dataset/812780/map?shareToken=30b94ff7-79a2-46e9-822e-0a97dbd26408

https://cloud.pix4d.com/dataset/788626/map?shareToken=38540ee0-e5a4-47e4-ab1a-6fb57ac48142
https://cloud.pix4d.com/dataset/665273/model?shareToken=612c5c7f-e47c-4721-8c2f-53ba80a6e544

Kuker-Ranken has been in business for nearly 100 years; Customer Service is our top priority, whether precision instruments, unmanned aircraft/drones, or construction support supplies.
Call us today for pricing on drones, training, and service! (800) 454-1310