scholarly journals Performance of aerial Bacillus thuringiensis var. israelensis applications in mixed saltmarsh-mangrove systems and use of affordable unmanned aerial systems to identify problematic levels of canopy cover

2020 ◽  
Author(s):  
Brian J. Johnson ◽  
Russell Manby ◽  
Gregor J. Devine
Keyword(s):  
Bacillus Thuringiensis ◽  
Multispectral Imaging ◽  
Mosquito Control ◽  
Larval Mortality ◽  
Canopy Cover ◽  
Ground Level ◽  
Unmanned Aerial Systems ◽  
Heterogeneous Environments ◽  
Vegetation Class ◽  
Aerial Systems

ABSTRACTBACKGROUNDIn the Australian southeast, the saltmarsh mosquito Aedes vigilax (Skuse) is the focus of area-wide larviciding campaigns employing the biological agent Bacillus thuringiensis var. israelensis (Bti). Although generally effective, frequent inundating tides and considerable mangrove cover can make control challenging. Here, we describe the efficacy and persistence of an aqueous Bti suspension (potency: 1200 International Toxic Units; strain AM65-52) within a mixed saltmarsh-mangrove system and the use of affordable unmanned aerial systems (UAS) to identify and map problematic levels of mangrove canopy cover.RESULTSHigh mangrove canopy density (>40% cover) reduced product deposition by 74.5% (0.013± 0.002 μl/cm2 vs. 0.051± 0.006 μl/cm2), larval mortality by 27.7% (60.7± 4.1% vs. 84.0± 2.4%), and ground level Bti concentrations by 32.03% (1144 ± 462.6 vs. 1683 ± 447.8 spores ml−1) relative to open saltmarsh. Persistence of product post-application was found to be low (80.6% loss at 6 h) resulting in negligible additional losses to tidal inundation 24 h post-application. UAS surveys accurately identified areas of high mangrove cover using both standard and multispectral imagery, although derived index values for this vegetation class were only moderately correlated with ground measurements (R2=0.17-0.38) at their most informative scales.CONCLUSIONThese findings highlight the complex operational challenges that affect coastal mosquito control in heterogeneous environments. The problem is exacerbated by continued mangrove transgression into saltmarsh habitat in the region. Emerging UAS technology can help operators optimize treatments by accurately identifying and mapping challenging canopy cover using both standard and multispectral imaging.

scholarly journals Augmentation of Traditional Forest Inventory and Airborne Laser Scanning with Unmanned Aerial Systems and Photogrammetry for Forest Monitoring

2018 ◽  
Vol 10 (10) ◽  
pp. 1562 ◽  
Author(s):  
Kathryn Fankhauser ◽  
Nikolay Strigul ◽  
Demetrios Gatziolis
Keyword(s):  
Laser Scanning ◽  
Canopy Cover ◽  
Tree Height ◽  
Forest Monitoring ◽  
Unmanned Aerial Systems ◽  
Aerial Laser Scanning ◽  
Forest Inventories ◽  
Airborne Laser ◽  
Aerial Systems

Forest inventories are constrained by resource-intensive fieldwork, while unmanned aerial systems (UASs) offer rapid, reliable, and replicable data collection and processing. This research leverages advancements in photogrammetry and market sensors and platforms to incorporate a UAS-based approach into existing forestry monitoring schemes. Digital imagery from a UAS was collected, photogrammetrically processed, and compared to in situ and aerial laser scanning (ALS)-derived plot tree counts and heights on a subsample of national forest plots in Oregon. UAS- and ALS-estimated tree counts agreed with each other (r2 = 0.96) and with field data (ALS r2 = 0.93, UAS r2 = 0.84). UAS photogrammetry also reasonably approximated mean plot tree height achieved by the field inventory (r2 = 0.82, RMSE = 2.92 m) and by ALS (r2 = 0.97, RMSE = 1.04 m). The use of both nadir-oriented and oblique UAS imagery as well as the availability of ALS-derived terrain descriptions likely sustain a robust performance of our approach across classes of canopy cover and tree height. It is possible to draw similar conclusions from any of the methods, suggesting that the efficient and responsive UAS method can enhance field measurement and ALS in longitudinal inventories. Additionally, advancing UAS technology and photogrammetry allows diverse users access to forest data and integrates updated methodologies with traditional forest monitoring.

scholarly journals Unmanned Aerial Systems for Monitoring Trace Tropospheric Gases

Atmosphere ◽  
2017 ◽  
Vol 8 (10) ◽  
pp. 206 ◽  
Author(s):  
Travis Schuyler ◽  
Marcelo Guzman
Keyword(s):  
Radiative Forcing ◽  
Trace Gases ◽  
Ground Level ◽  
Oxide Semiconductor ◽  
Atmospheric Composition ◽  
Cavity Surface ◽  
Unmanned Aerial Systems ◽  
Spatiotemporal Resolution ◽  
Atmospheric Trace Gases ◽  
Aerial Systems

The emission of greenhouse gases (GHGs) has changed the composition of the atmosphere during the Anthropocene. Accurately documenting the sources and magnitude of GHGs emission is an important undertaking for discriminating the contributions of different processes to radiative forcing. Currently there is no mobile platform that is able to quantify trace gases at altitudes <100 m above ground level that can achieve spatiotemporal resolution on the order of meters and seconds. Unmanned aerial systems (UASs) can be deployed on-site in minutes and can support the payloads necessary to quantify trace gases. Therefore, current efforts combine the use of UASs available on the civilian market with inexpensively designed analytical systems for monitoring atmospheric trace gases. In this context, this perspective introduces the most relevant classes of UASs available and evaluates their suitability to operate three kinds of detectors for atmospheric trace gases. The three subsets of UASs discussed are: (1) micro aerial vehicles (MAVs); (2) vertical take-off and landing (VTOL); and, (3) low-altitude short endurance (LASE) systems. The trace gas detectors evaluated are first the vertical cavity surface emitting laser (VCSEL), which is an infrared laser-absorption technique; second two types of metal-oxide semiconductor sensors; and, third a modified catalytic type sensor. UASs with wingspans under 3 m that can carry up to 5 kg a few hundred meters high for at least 30 min provide the best cost and convenience compromise for sensors deployment. Future efforts should be focused on the calibration and validation of lightweight analytical systems mounted on UASs for quantifying trace atmospheric gases. In conclusion, UASs offer new and exciting opportunities to study atmospheric composition and its effect on weather patterns and climate change.

scholarly journals Design and Evaluation of Sensor Housing for Boundary Layer Profiling Using Multirotors

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2481 ◽  
Author(s):  
Ashraful Islam ◽  
Adam L. Houston ◽  
Ajay Shankar ◽  
Carrick Detweiler
Keyword(s):  
Boundary Layer ◽  
High Speed ◽  
Ground Level ◽  
Radiation Shielding ◽  
Unmanned Aerial Systems ◽  
Heat Sources ◽  
Wide Range ◽  
Artificial Heat ◽  
Aerial Systems ◽  
Airborne Sensors

Traditional configurations for mounting Temperature–Humidity (TH) sensors on multirotor Unmanned Aerial Systems (UASs) often suffer from insufficient radiation shielding, exposure to mixed and turbulent air from propellers, and inconsistent aspiration while situated in the wake of the UAS. Descent profiles using traditional methods are unreliable (when compared to an ascent profile) due to the turbulent mixing of air by the UAS while descending into that flow field. Consequently, atmospheric boundary layer profiles that rely on such configurations are bias-prone and unreliable in certain flight patterns (such as descent). This article describes and evaluates a novel sensor housing designed to shield airborne sensors from artificial heat sources and artificial wet-bulbing while pulling air from outside the rotor wash influence. The housing is mounted above the propellers to exploit the rotor-induced pressure deficits that passively induce a high-speed laminar airflow to aspirate the sensor consistently. Our design is modular, accommodates a variety of other sensors, and would be compatible with a wide range of commercially available multirotors. Extensive flight tests conducted at altitudes up to 500 m Above Ground Level (AGL) show that the housing facilitates reliable measurements of the boundary layer phenomena and is invariant in orientation to the ambient wind, even at high vertical/horizontal speeds (up to 5 m/s) for the UAS. A low standard deviation of errors shows a good agreement between the ascent and descent profiles and proves our unique design is reliable for various UAS missions.

scholarly journals Multispectral imaging and unmanned aerial systems for cotton plant phenotyping

PLoS ONE ◽  
2019 ◽  
Vol 14 (2) ◽  
pp. e0205083 ◽  
Author(s):  
Rui Xu ◽  
Changying Li ◽  
Andrew H. Paterson
Keyword(s):  
Cotton Plant ◽  
Multispectral Imaging ◽  
Plant Phenotyping ◽  
Unmanned Aerial Systems ◽  
Aerial Systems

scholarly journals Assessing the Ability of Image Based Point Clouds Captured from a UAV to Measure the Terrain in the Presence of Canopy Cover

Forests ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 284 ◽  
Author(s):  
Luke Wallace ◽  
Chris Bellman ◽  
Bryan Hally ◽  
Jaime Hernandez ◽  
Simon Jones ◽  
...  
Keyword(s):  
Ground Surface ◽  
Canopy Cover ◽  
Weather Conditions ◽  
Point Clouds ◽  
Unmanned Aerial Systems ◽  
Image Capture ◽  
Terrain Model ◽  
Processing Strategies ◽  
Aerial Systems

Point clouds captured from Unmanned Aerial Systems are increasingly relied upon to provide information describing the structure of forests. The quality of the information derived from these point clouds is dependent on a range of variables, including the type and structure of the forest, weather conditions and flying parameters. A key requirement to achieve accurate estimates of height based metrics describing forest structure is a source of ground information. This study explores the availability and reliability of ground surface points available within point clouds captured in six forests of different structure (canopy cover and height), using three image capture and processing strategies, consisting of nadir, oblique and composite nadir/oblique image networks. The ground information was extracted through manual segmentation of the point clouds as well as through the use of two commonly used ground filters, LAStools lasground and the Cloth Simulation Filter. The outcomes of these strategies were assessed against ground control captured with a Total Station. Results indicate that a small increase in the number of ground points captured (between 0 and 5% of a 10 m radius plot) can be achieved through the use of a composite image network. In the case of manually identified ground points, this reduced the root mean square error (RMSE) error of the terrain model by between 1 and 11 cm, with greater reductions seen in plots with high canopy cover. The ground filters trialled were not able to exploit the extra information in the point clouds and inconsistent results in terrain RMSE were obtained across the various plots and imaging network configurations. The use of a composite network also provided greater penetration into the canopy, which is likely to improve the representation of mid-canopy elements.

scholarly journals On-flight intercomparison of three miniature aerosol absorption sensors using Unmanned Aerial Systems (UAS)

2019 ◽  
Author(s):  
Michael Pikridas ◽  
Spiros Bezantakos ◽  
Grisa Močnik ◽  
Christos Keleshis ◽  
Fred Brechtel ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Absorption Coefficient ◽  
Ground Level ◽  
Early Morning ◽  
Urban Site ◽  
Unmanned Aerial Systems ◽  
Measured Signal ◽  
Aerosol Absorption ◽  
Fast Development ◽  
Aerial Systems

Abstract. The present study investigates for the first time, the ground and flight performances of three miniaturized aerosol absorption sensors integrated on-board of Unmanned Aerial Systems (UAS). These sensors were evaluated during two contrasted field campaigns performed respectively at an urban site (Athens, Greece) impacted mainly by local traffic and domestic wood burning sources and at a remote regional background site (Agia Marina, Cyprus) impacted by long-range transported sources including dust. The three sensors were intercompared at the ground level against two commercially available instruments (MAAP and AE33) used as a reference. The measured signal of the three sensors was converted into absorption coefficient, equivalent black carbon concentration (eBC) and, when applicable, to signal saturation corrections following the suggestions of the manufacturers. Despite the diversity of the aerosol origin, chemical composition, sources and concentration levels during the two campaigns, the aerosol absorption sensors exhibited similar behavior against the reference instruments. The deviation from the reference during both campaigns concerning (eBC) mass was less than 8 %, suggesting that those miniature sensors that report BC mass are tuned/corrected to measure more accurately eBC rather than the absorption coefficient which deviated at least 15 %. The overall potential use of miniature aerosol absorption sensor on-board UAS is also illustrated here. UAS-based absorption measurements were used to investigate the vertical distribution of eBC over Athens up to 1 km above sea level during January 2016, reaching the top of the planetary boundary layer (PBL). Our results highlighted a heterogeneous boundary layer concentration of absorbing aerosol, especially in the early morning hours with the concurrent peak traffic emissions at ground-level and fast development of the boundary layer. Vertical homogeneity was achieved when the boundary layer depth became stable.

scholarly journals Evaluation of Ground Surface Models Derived from Unmanned Aerial Systems with Digital Aerial Photogrammetry in a Disturbed Conifer Forest

2019 ◽  
Vol 11 (1) ◽  
pp. 84 ◽  
Author(s):  
Alexander Graham ◽  
Nicholas Coops ◽  
Michael Wilcox ◽  
Andrew Plowright
Keyword(s):  
Canopy Cover ◽  
Point Clouds ◽  
Unmanned Aerial Systems ◽  
Optimal Parameters ◽  
Conifer Forest ◽  
Terrain Modeling ◽  
Ground Truth Data ◽  
Aerial Photogrammetry ◽  
Terrain Slope ◽  
Aerial Systems

Detailed vertical forest structure information can be remotely sensed by combining technologies of unmanned aerial systems (UAS) and digital aerial photogrammetry (DAP). A key limitation in the application of DAP methods, however, is the inability to produce accurate digital elevation models (DEM) in areas of dense vegetation. This study investigates the terrain modeling potential of UAS-DAP methods within a temperate conifer forest in British Columbia, Canada. UAS-acquired images were photogrammetrically processed to produce high-resolution DAP point clouds. To evaluate the terrain modeling ability of DAP, first, a sensitivity analysis was conducted to estimate optimal parameters of three ground-point classification algorithms designed for airborne laser scanning (ALS). Algorithms tested include progressive triangulated irregular network (TIN) densification (PTD), hierarchical robust interpolation (HRI) and simple progressive morphological filtering (SMRF). Points were classified as ground from the ALS and served as ground-truth data to which UAS-DAP derived DEMs were compared. The proportion of area with root mean square error (RMSE) <1.5 m were 56.5%, 51.6% and 52.3% for the PTD, HRI and SMRF methods respectively. To assess the influence of terrain slope and canopy cover, error values of DAP-DEMs produced using optimal parameters were compared to stratified classes of canopy cover and slope generated from ALS point clouds. Results indicate that canopy cover was approximately three times more influential on RMSE than terrain slope.

scholarly journals On-flight intercomparison of three miniature aerosol absorption sensors using unmanned aerial systems (UASs)

2019 ◽  
Vol 12 (12) ◽  
pp. 6425-6447 ◽  
Author(s):  
Michael Pikridas ◽  
Spiros Bezantakos ◽  
Griša Močnik ◽  
Christos Keleshis ◽  
Fred Brechtel ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Absorption Coefficient ◽  
Black Carbon ◽  
Ground Level ◽  
Urban Site ◽  
Unmanned Aerial Systems ◽  
Measured Signal ◽  
Aerosol Absorption ◽  
Aerial Systems ◽  
Miniaturized Sensors

Abstract. The present study investigates and compares the ground and in-flight performance of three miniaturized aerosol absorption sensors integrated on board small-sized Unmanned Aerial Systems (UASs). These sensors were evaluated during two contrasted field campaigns performed at an urban site, impacted mainly by local traffic and domestic wood burning sources (Athens, Greece), and at a remote regional background site, impacted by long-range transported sources including dust (Cyprus Atmospheric Observatory, Agia Marina Xyliatou, Cyprus). The miniaturized sensors were first intercompared at the ground-level against two commercially available instruments used as a reference. The measured signal of the miniaturized sensors was converted into the absorption coefficient and equivalent black carbon concentration (eBC). When applicable, signal saturation corrections were applied, following the suggestions of the manufacturers. The aerosol absorption sensors exhibited similar behavior against the reference instruments during the two campaigns, despite the diversity of the aerosol origin, chemical composition, sources, and concentration levels. The deviation from the reference during both campaigns concerning (eBC) mass was less than 8 %, while for the absorption coefficient it was at least 15 %. This indicates that those sensors that report black carbon mass are tuned and corrected to measure eBC more accurately than the absorption coefficient. The overall potential use of miniature aerosol absorption sensors on board small UASs is also illustrated. UAS-based absorption measurements were used to investigate the vertical distribution of eBC over Athens up to 1 km above sea level during January 2016, exceeding the top of the planetary boundary layer (PBL). Our results reveal a heterogeneous boundary layer concentration of absorbing aerosol within the PBL intensified in the early morning hours due to the concurrent peak traffic emissions at ground-level and the fast development of the boundary layer. After the full development of the PBL, homogenous concentrations are observed from 100 m a.g.l. to the PBL top.

High throughput phenotyping of tomato spot wilt disease in peanuts using unmanned aerial systems and multispectral imaging

2017 ◽  
Vol 20 (3) ◽  
pp. 4-12 ◽  
Author(s):  
Aaron Patrick ◽  
Sara Pelham ◽  
Albert Culbreath ◽  
C. Corely Holbrook ◽  
Ignacio Jose De Godoy ◽  
...  
Keyword(s):  
High Throughput ◽  
Multispectral Imaging ◽  
Wilt Disease ◽  
Unmanned Aerial Systems ◽  
High Throughput Phenotyping ◽  
Aerial Systems

scholarly journals University of Kentucky measurements of wind, temperature, pressure and humidity in support of LAPSE-RATE using multisite fixed-wing and rotorcraft unmanned aerial systems

2020 ◽  
Vol 12 (3) ◽  
pp. 1759-1773 ◽  
Author(s):  
Sean C. C. Bailey ◽  
Michael P. Sama ◽  
Caleb A. Canter ◽  
L. Felipe Pampolini ◽  
Zachary S. Lippay ◽  
...  
Keyword(s):  
Ground Level ◽  
Boundary Layer Transition ◽  
Lower Atmosphere ◽  
Lapse Rate ◽  
Data Repository ◽  
Unmanned Aerial Systems ◽  
University Of Kentucky ◽  
Layer Transition ◽  
The University ◽  
Aerial Systems

Abstract. In July 2018, unmanned aerial systems (UASs) were deployed to measure the properties of the lower atmosphere within the San Luis Valley, an elevated valley in Colorado, USA, as part of the Lower Atmospheric Profiling Studies at Elevation – a Remotely-piloted Aircraft Team Experiment (LAPSE-RATE). Measurement objectives included detailing boundary layer transition, canyon cold-air drainage and convection initiation within the valley. Details of the contribution to LAPSE-RATE made by the University of Kentucky are provided here, which include measurements by seven different fixed-wing and rotorcraft UASs totaling over 178 flights with validated data. The data from these coordinated UAS flights consist of thermodynamic and kinematic variables (air temperature, humidity, pressure, wind speed and direction) and include vertical profiles up to 900 m above the ground level and horizontal transects up to 1500 m in length. These measurements have been quality controlled and are openly available in the Zenodo LAPSE-RATE community data repository (https://zenodo.org/communities/lapse-rate/, last access: 23 July 2020), with the University of Kentucky data available at https://doi.org/10.5281/zenodo.3701845 (Bailey et al., 2020).

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