Drones for the geosciences: a new eye in the sky
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winter 2018
drones for the geosciences: a new eye in the sky
S tudies of planet Earth are best done
using a wide variety of tools because
geologic processes occur at all scales. For
Drones flown at low altitude can
capture surface and topographic informa-
tion that has traditionally been acquired
for repeat photography of long-lived events
(such as stream erosion). The combination
of these factors is encouraging a growing
example, satellites and seismometers are from Airborne LiDAR (Light Detection number of geoscientists to add drones to
used to study Earth at the global scale, and Ranging) or TLS (Terrestrial Laser their geologic toolboxes. In the spring of
whereas microscopes and mass spectrom- Scanning). Airborne LiDAR surveys are best 2017, the New Mexico Bureau of Geology
eters are used to study Earth at the crystal for large areas (more than 5 square miles), began exploring the capabilities of drones
and atomic scales. Earth science discoveries whereas low-altitude drone surveys are ideal to conduct geologic research and provide
often correlate with technological advances for small to moderate-sized sites (less than up-to-date information about the geology
in the tools used to record observations and 5 square miles). Drone surveys and image of our state.
make measurements. In some cases, these processing software can generate maps with
advances allow scientists to detect what was similar accuracies and higher resolutions Unmanned aircraft types
previously unknown. One such tool, which than many established photogrammetry
Drones are classified into two broad
is just starting to revolutionize the study of (whereby measurements are made from
categories, rotary-wing and fixed-wing, each
planet Earth, is unmanned aircraft systems photographs) techniques for a fraction of
with their own benefits and limitations.
(UAS), more commonly known as drones. the cost. Additionally, most drones are
The main benefits of rotary-wing drones,
Aerial photography and remote small, lightweight, and highly mobile, and
such as quadcopters (four propellers) and
sensing (a technique that involves acquiring thus are rapidly deployed to capture short-
hexacopters (six propellers), are vertical take-
information about an object and/or area lived events (such as debris flows) or used
off and landing, and the ability to hover. As a
from a distance) produce important
data that provide context for
field-based studies. Information
related to surface topography and
landforms—features that are com-
monly too large to observe at ground
level—help geologists understand
how their measurements at the
outcrop scale fit into a larger regional
picture. Evaluating and mitigating
geologic hazards (such as floods and
volcanic eruptions), monitoring
surface processes (such as stream
erosion and landslides), managing
water resources, and constructing
geologic maps are just a few facets of
the geosciences that regularly need
up-to-date information and observa-
tion of Earth’s surface. Historically,
on-demand aerial photography and
remote sensing from planes and
helicopters have only been available
to large, well-funded studies, or
provided as parts of regional studies
that often miss the immediate after-
math of unexpected geologic events A New Mexico Tech student (bottom left of photo) flying a modified, off-the-shelf quadcopter to inspect
such as earthquakes and tsunamis. outcrops outside of Socorro, New Mexico.
Published by the New Mexico Bureau of Geology and Mineral Resources • A Division of New Mexico Tech
Satellite Imagery Airplane Imagery Drone Imagery
A) 52800 ft B) 1500 ft C) 30 ft
10 miles
qComparison of different types of imagery used in the geosciences. (A) is an orthomosaic map generated from LANDSAT satellite images, where
each pixel is 30 m (98.43 feet) x 30 m. (B) is a NAIP (National Agricultural Imagery Program) orthomosaic map generated from fixed-wing
airplane images where each pixel is 1 m (3.28 feet) x 1 m. (C) is an orthomosaic map generated from drone images where each pixel is 1.5 cm
(0.59 inches) x 1.5 cm. Maps are zoomed to their highest resolution such that zooming further creates pixilation. Note the change in scale
between the three maps. The box at the center of map (A) shows the extent of map (B). The box at the center of map (B) shows the extent of
map (C). The drone orthomosaic is best for imaging small- to medium-scale features (such as mud cracks, boulders, outcrops, and individual
vegetation elements), whereas the 1-m and 30-m images are best for medium- to large-scale features (such as rivers and mountains). This com-
parison demonstrates the amazing detail that can be captured by drone imaging and the complimentary natures of different imaging techniques.
result, rotary-wing drones are ideal for small and thus can survey larger areas with a those designed for high-end consumers
areas where precision flying is critical (such single battery charge (typically about 20 to and industrial missions, are equipped with
as in narrow canyons) or when hovering is 60 minutes, depending on the model and onboard GPS units, barometers, and inertial
necessary to make repeat measurements. operating conditions). Both rotary- and measurement units that allow pilots to
Furthermore, hovering capabilities and fixed-wing drones can be outfitted with navigate aircraft smoothly and precisely.
the slower speeds of rotary-wing aircraft cameras mounted on motorized gimbals, Additionally, the newest drone models
allow for more time to assess environmental a device that steadies the camera, ensuring contain highly advanced, obstacle-avoidance
conditions, which typically provides a safer that the images are high resolution and equipment, such as infrared cameras, dual
learning environment for new users. In free of motion blur. A professional-level, vision sensors, and ultrasonic rangefinders.
contrast, fixed-wing drones are usually of research-ready drone kit (drone, one or These features help prevent crashes from
simpler construction, fly at faster speeds, more batteries, camera, and controller) operator error and weather conditions that
begins at about $1,500 to would otherwise result in loss of equipment
$3,000, plus additional costs and data, and downtime for maintenance.
for advanced hardware such as Furthermore, the latest versions of popular
thermal cameras and differen- flight-planning software prevent flying near
tial GPS. However, entry-level major airports and in restricted areas, help-
drones for hobbyists cost as ing to minimize the danger of drone traffic
little as a few hundred dollars, in the national airspace.
and may be suitable for some
earth science applications. Image acquisition and processing
One of the most important Advances in image processing software, in
reasons why drones have particular those that use Structure-from-
seen such a recent increase in Motion (SfM) algorithms, have paralleled
popularity is operational ease the technological advances in aircraft design
of use. Even for inexperienced and operation. SfM is a photographic tech-
users, operating a drone at a nique capable of generating 3-dimensional
moderate level of expertise can (3-D) information from 2-dimensional
be accomplished within a short photos. The process involves identifying
time frame. This is largely the and matching ‘keypoints’ (such as fractures
result of advances in software, on a boulder) between overlapping photos,
such as machine vision (where and uses triangulation calculations and
A typical drone flight includes taking pictures from a grid a computer recognizes objects) related methods to determine the 3-D
pattern looking straight down (white solid line) and/or an and the miniaturization of location for the set of data points (known
orbital path taking photos at an angle (white dashed line). electronics, which not only as a point cloud) that are generated. Each
The overlapping drone photos (yellow colored boxes) show offers smaller sensors but more
how the spatial relationship of a keypoint (the red dot) point within the point cloud has a unique
computing power in a smaller latitude, longitude, and elevation value. SfM
changes from picture to picture. The three black lines show
how triangulating the keypoint among images can locate and lighter package. Almost map products include ultra high-resolution
features and generate 3-D information. The 3-D model of all modern drones, especially orthomosaics (an image that is geometrically
this outcrop is found in the figure on page 4.
new mexico earth matters 2 winter 2018
corrected for distortions) and digital surface camera settings that minimize motion blur. study is to understand the spatial relation-
models (elevation maps that include surficial Furthermore, moving objects (such as people, ships of only the features within the map,
features such as trees and structures). User- vehicles, cloud shadows, and foliage in breezy then such accuracy is sufficient. However,
friendly, proprietary (such as Drone2Map™) winds) can result in distorted maps. both relative and absolute accuracy can be
and open-source (such as OpenDroneMap) Finally, lighting conditions can also improved by placing precisely measured
software is readily available for automated affect the quality of the maps. The best ground control points in the map area,
image processing, usually requiring nothing lighting conditions for drone mapping are: which are later used to calibrate the maps
more than uploading the photos and minor 1) overcast skies, when clouds diffuse the during image processing.
tweaking of the image processing settings. light over large areas; 2) immediately before
Photo acquisition via drones shares and after sunrise and sunset, when there is Drone Applications
similarities to traditional aerial surveys, enough light but no shadows; and 3) near
The affordability and mobility of drones,
but also involves significant differences. solar-noon, when the sun is at its highest
coupled with the high resolution and
Drone photos are typically captured along and the impact from shadows is minimized.
accuracy of SfM generated maps, has led
a grid-pattern flight path that encompasses Features within long shadows at dawn and
to widespread drone use by geoscientists
an area larger than the target of interest. dusk may be hard to recognize and could
at universities, federal and state geologic
In general, processing the images with the negatively affect the map quality.
surveys, and within industry. The following
SfM technique works best when there is Depending on the purpose of the project,
discussion summarizes how geoscientists are
a high-degree of overlap between photos researchers must make choices on the desired
currently using drones, the potential for their
(more than or equal to 70% overlap) and accuracy (how close a measurement is to
use here in New Mexico, and how the tech-
the photos are taken at a cruising altitude the true value) and resolution (the smallest
nology may advance in the coming years.
of 250–400 feet above ground surface. “thing” that can be measured) of their SfM
Currently, the maximum altitude that maps. The “ground sampling distance”
Drones for geomorphic and
commercial drone pilots can operate under (the distance from the center of a pixel to
Federal Aviation Administration (FAA) rules
field geology studies
the adjacent pixel) of SfM maps is largely
is 400 feet above the ground. Flying at low controlled by camera settings and the altitude The majority of published drone studies
altitudes can improve the resolution of the of the drone. Given the 400-foot altitude have focused on the mapping of relatively
maps, but increases flying time, may involve limit and the camera resolution on modern young features and landforms on Earth’s
multiple battery exchanges, and requires drones, the average ground sampling distance surface. The high-resolution of SfM maps
more computational power due to the for most maps is 1–5 cm (0.4-2.0 inches) can provide better characterization of such
increased number of photos per unit area. with a “relative accuracy” (the accuracy of features, or, in some cases, help discover
In addition to capturing photos in a features within the map itself) of 1 to 3 unknown landforms. High-frequency
grid pattern, pilots commonly take oblique times that of the ground sampling distance. (hourly to weekly) repeat drone observations
photos to image vertical features, such as At this resolution and accuracy, both large are leading to new insights into geologic
cliffs and canyon walls, or complicated and ultra-small topographic features can processes such as mass wasting (landslides,
3-D features. Oblique photos are useful be identified, mapped, and analyzed. The rockfalls, mudflows, etc.), stream incision,
for increasing the accuracy of elevation “absolute accuracy” of the maps (the location dune migration, and erosion. High-
measurements, and are necessary if the end of features in the map compared to their true resolution SfM maps can capture grain-size
product is a high-resolution 3-D model of position on Earth) is mostly controlled by the variations within streams and glacial
a feature. accuracy of the GPS unit used for the survey. moraines, and is therefore a powerful tool
Because the SfM technique involves The GPS units built into most drones have for studying rivers and glacial processes.
matching ‘keypoints’ between overlapping meter-scale accuracy, similar to the accuracy In addition to geomorphology, drones
images, care must be taken to choose of handheld GPS units. If the goal of the are cost effective for outcrop-scale studies,
¢
A)
200 ft
B)
Arroyo Channel
Elevation
High
Low
Drone-generated orthomosaic (A) and digital surface model (B) of Arroyo del Tajo, an arroyo east of Socorro. The colors of Map B represent
elevation, from higher in red colors to lower in blue colors. The images used to generate this map were captured at about 200 feet above
ground level and processed using SfM software. The average resolution is 1.74 cm (0.69 inches).
new mexico earth matters 3 winter 2018
A) A) 200 B)
Feet
q
x y
(32 m
)
5 ft
99
x y Elevation
High
31.3 m
(102.8 ft)
B) Low
UAS-SfM orthomosaic (A) and digital surface (elevation) model (B) of the
JWS sinkhole in Eddy County, southeastern New Mexico, which collapsed in
2008. Map A also includes a measurement of the diameter of the sinkhole and
a topographic profile (inset graph at bottom of the figure) from ArcGIS. The
digital surface model contains topographic contours at 5-foot intervals. Repeat
drone surveys can show if such sinkholes change over time.
As 3-D mapping methods surveys have the potential to find abandoned
and software continue to mines and mining equipment. Here in New
develop, drones flights and SfM Mexico, large plumes of methane, a potent
maps will likely be a major com- greenhouse gas, exist over the natural gas
C) ponent of the workflow. Some fields and drilling operations of the San Juan
new drones are as small and light and Permian Basins. Whereas satellites and
as smartphones, easily fit in back- planes surveys are used to understand the
packs, and will likely become large-scale aspects of methane leaks, drones
handy tools for geologists to could be deployed for local “well-to-well”
scout outcrops, plan routes, and monitoring. Small, thermal cameras and
perhaps even to collect samples gas-sensing equipment mounted on drones
from hard-to-reach areas. can investigate point sources of escaping gas
at drilling sites and along pipelines. Such
Drones for industrial inexpensive studies could lead to reduced
geology emissions, increased profits, and more tax
For many of the same reasons revenue for the state.
Comparison of visualization tools for a beautifully
exposed angular unconformity (A) in the face of a mesa drones are used to document
at San Lorenzo Canyon, Socorro County. Google Earth geomorphic changes to Earth’s Drones for hazards
images (B) sometimes distort steep vertical features, such surface, drones are becoming One of the most significant uses of drones is
as this outcrop, or are incapable of showing them at all. In increasingly important for assessing and monitoring geologic hazards.
contrast, the 3-D SfM model (C) accurately shows features
industrial geologic applications. Following the November 2016 magnitude
such as inclined sedimentary layers. The 3-D model was
generated from 229 orthogonal and oblique drone photos. Drones are now used throughout 7.8 earthquake on New Zealand’s South
The view is about 95 m (312 feet) across. A 3-D video tour the life-cycle of mining and Island, drones provided critical, initial
of the outcrop can be found at http://geoinfo.nmt.edu/ drilling operations. Drones information about the surface ruptures along
repository/index.cfml?rid=20180001. outfitted with magnetometers faults and the locations and magnitudes of
(a device used to locate magnetic landslides. Volcano observatories are using
mapping and characterizing intermediate- minerals) are useful for mineral exploration. drone-based, optical and thermal imagery
scale features such as fault traces, sedimentary Repeat surveys of active mines and drill to track lava flows and changes in the shape
layering, and stratigraphic relationships. pads provide near real-time information of volcanic vents. Drone-mounted gas
Highly detailed mapping projects, such as regarding daily operations. High-resolution monitoring equipment can be flown through
those related to paleoseismicity (ancient digital surface models allow mine operators volcanic plumes to directly measure the gases
earthquakes) and infrastructure development to measure stockpiled inventories, and to that geologists use to help predict eruptions.
(such as construction projects), can use quickly quantify how material is transported Emergency organizations that respond to
drones to create high-resolution orthomosaics through the work area. Drones can monitor geological and weather-related hazards are
and digital surface models. Important the slope stability of open-pit walls and using drones on search and rescue missions,
geologic relationships are commonly waste-rock piles, as well as rapidly inspect for infrastructure assessment, and for survey-
exposed in cliff faces or similar inaccessible equipment such as drilling rigs and ing damage. Drone manufacturers are
locations. Ground-based photos and laser offshore drilling platforms, thus limiting developing aircraft capable of delivering
scanning may be inadequate to resolve these human exposure to hazardous working goods such as medical supplies, food, and
outcrops, and other visualization tools like environments. Drones also play a role water for disaster relief. Likewise, researchers
Google Earth tend to distort large vertical in the environmental impacts of mining are designing drones that are themselves
features. However, oblique-drone photos and drilling. High-resolution pre- and mobile wireless hotspots to assist with
captured at altitude, and 3-D SfM models, post-mining and drilling maps are useful for emergency communication operations.
are an attractive solution. reclamation efforts. Drone reconnaissance
new mexico earth matters 4 winter 2018
New Mexico is a geologically active The future of drones, however, is not
state, and many of our geologic hazards can without challenges. The FAA is currently
be investigated with drones. For example, attempting to develop rules for drone pilots
measurements of land subsidence related to that will protect privacy and enhance safety
sinkholes in eastern New Mexico or detecting while allowing the industry to achieve its
slope movement in the Rio Grande gorge, potential. In the summer of 2016, the FAA
are well within the capabilities of drone provided a pathway for drone pilots to
photogrammetry. Burned landscapes are obtain licensing for commercial activities.
notoriously unstable and destructive debris In the fall of 2017, the FAA developed the
flows are common after wildfires. However, UAS Integration Pilot Program to explore
these landscapes can be investigated with best practices to safely integrate drones into
repeat deployment of drones in a safer the airspace.
manner than ground-based surveys. Although Stable weather, vast amounts of
large, damaging earthquakes and volcanic unrestricted airspace, limited vegetation,
eruptions are infrequent in New Mexico, and diverse geology make New Mexico a
when they do occur, drones would inevitably prime location to use and test drones and Volume 18, Number 1
provide some of the earliest data needed by related scientific instruments. Researchers Published twice annually by the
scientists and first responders. from the New Mexico Bureau of Geology are new mexico bureau of geology
continuing to explore the possibilities and and mineral resources
Drones for climate change capabilities of drones as tools to meet the Nelia Dunbar
diverse geologic needs of our state. Director and State Geologist
Researchers from around the world are using a division of
drones to study climate change. Glaciologists —Matthew Zimmerer
new mexico institute of
are finding that repeat surveys with drones are mining and technology
a useful tool for tracking rapid physical changes Matt Zimmerer is a field geologist with the
Dr. Stephen G. Wells
to glaciers. Scientists are also using drones to New Mexico Bureau of Geology and Mineral President
monitor the annual progression of moss on the Resources at New Mexico Tech, and a licensed 801 Leroy Place
Antarctic Peninsula to approximate the pace FAA remote pilot. He is currently developing Socorro, New Mexico 87801-4750
of climate change. In the southwestern U.S., a drone program at the bureau. Anyone
Bureau Albuquerque office
increasing temperatures are causing longer interested in using drones for either work or 2808 Central SE
and more severe droughts. One impact is recreation should visit the FAA website Albuquerque, New Mexico 87106
declining forest health, both from decreased (https://www.faa.gov/uas/). (505) 366-2530
precipitation and an expansion of invasive
species. Drones equipped with a basic digital Special thanks for helpful reviews from Aaron Board of Regents
camera can identify water-deprived vegetation, Curtis and Brian Gootee, as well as these Ex Officio
and images can be processed to determine individuals and groups that helped make this Susana Martinez
the relative “greenness” of a forest, which is Governor of New Mexico
publication possible: Jake Ross, Nels Iverson,
directly related to its health. Drones outfit- Dr. Barbara Damron
Phil Miller, Mark Mansell, Kelsey McNamara, Secretary of Higher Education
ted with multi-spectral cameras capable of Lewis Land, Nelia Dunbar, Mike Timmons,
photographing the near-infrared spectrum Paul Bauer, Sevilleta National Wildlife Refuge, Appointed
are becoming common tools for farmers to Deborah Peacock
and the New Mexico State Land Office. President, 2017–2022, Corrales
monitor crop health. Such technology could
also be used to map the declining health Jerry A. Armijo
of the largest cottonwood-willow forest in The bureau’s drone “Tommy.” See Secretary-Treasurer, 2015–2020, Socorro
North America, the bosque along the http://geoinfo.nmt.edu/repository/ David Gonzales
index.cfml?rid=20180001, for a video of 2015–2020, Farmington
Rio Grande. Drone surveys to inspect
Tommy in action. Donald Monette
irrigation ditches and water retention
2015–2018, Socorro
structures, monitor surface water runoff,
Emily Silva, student member
and even map the levelness of farmland, 2017–2018, Alamagordo
may provide New Mexican water managers
with new strategies to deal with declining Editor
water resources. Paul Bauer
Production, Layout & Design
The future of drones Gina D’Ambrosio
Unmanned aircraft systems, structure- Graphics
from-motion photogrammetry, and a Matthew Zimmerer, Leo Gabaldon
diverse suite of drone-mounted instru-
ments are ushering in an exciting Visit our website at: geoinfo.nmt.edu
and potentially transformative period Earth Matters is a free publication.
in the geosciences. Where on-demand For subscription information please call
aerial imaging and photogrammetry was (575) 835-5490, or e-mail us at
unavailable to most, drones are allowing the publications@nmbg.nmt.edu
next generation of researchers to collect data
quickly and inexpensively. Cover photo of Chimney Rock, New Mexico
© Matthew Zimmerer
new mexico earth matters 5 winter 2018
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bureau news
administrators, to promote our services, and is now available online. She specializes
information, teacher training, and K-12 in geochemistry and volcanology and
outreach. She will be guiding groups previously worked on the documentary
through the Mineral Museum, providing “Sleeping Monsters, Sacred Fires: Volcanoes
classroom demonstrations, coordinating of New Mexico.”
the annual Rockin’ Around New Mexico
geology class, and editing Lite Geology.
Prior to joining the bureau, Cynthia was
a science teacher at Socorro High School.
Bonnie Frey receives
IMPACT! Award
Governor Martinez recognizes Susie
Welch In October, the New Mexico Network
for Women in Science & Engineering
Susie Welch, our recently retired honored Bonnie Frey, Geochemist and
Outreach Coordinator, was cited for Chemistry Laboratory Manager. The
outstanding accomplishments and award is given to a New Mexico woman
invaluable contributions to the state who encourages women to enter into
of New Mexico. The award recognizes Nelia Dunbar looking at volcanic ash in ice
science, technology, engineering, math- cores on NOVA “Killer Volcanoes” program.
Susie’s 21 years of leadership in “Rockin’ ematics, and allied professions. Bonnie
Around New Mexico,” our earth science received this award, in part, because of
educational program for New Mexico For information about the bureau
the mentoring that she has provided to and our publications:
teachers. Congratulations to Susie on the students involved in the NM EPSCoR
well-deserved citation, and her retire- uranium team, of which she is a co-lead. Visit our website at
ment after 26 years of bureau service! http://geoinfo.nmt.edu
Call (575) 835-5490, e-mail us at
Nelia Dunbar in PBS NOVA publications@nmbg.nmt.edu,
Cynthia Connolly to run Program “Killer Volcanoes”
Outreach Program or visit the bureau store at the corner of
Dr. Nelia Dunbar is the Director of the Bullock and Leroy on the campus of New
As our new Education Outreach Bureau of Geology and serves as the State Mexico Tech, 801 Leroy Place,
Manager, Cynthia will work Geologist. The program aired in October
Socorro, NM, 87801
with students, teachers, staff, and
new mexico earth matters winter 2018
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