Remote-controlled Aerial Vehicle Research Articles

Quantifying the effectiveness of shaded fuel breaks from ground-based, aerial, and spaceborne observations

Shaded fuel breaks are treatments that aim to mitigate wildfires by establishing linearly aligned locations where wildfire suppression efforts can be more effective at stopping wildfires. Despite the potential of fuel breaks to alter fire behavior, there have been limited quantitative assessments of their effectiveness following exposure to wildfires. In addition, wildfires often occurin complex terrains that are difficult to access with ground vehicles and sensors, posing challenges for data acquisition. However, the use of Remote-controlled Aerial Vehicles (RAVs), such as drones, is becoming increasingly popular as a viable means of conducting high-resolution observations in areas of interest. This study presents the results from a unique opportunity to utilize three distinct observation scale platforms (in-situ, aerial, and spaceborne) to investigate the burn severity impacts across a prior shaded fuel break that serendipitously encountered the 2020 Creek Fire in the Sierra Nevada forests of California, USA. To provide a direct measure of fire severity, ground-based measurements determined the percentage crown volume (PCV) of scorch and char as a function of distance from the fuel break edge. Along five transects of the fuel break, we also utilized visible bands from drone imagery and digital photogrammetry, to generate georeferenced orthophotos and quantify vegetation health using the Green Leaf Index (GLI). We also quantified burn severity by computing the Delta Normalized Burn Ratio (dNBR) and vegetation health using the Normalized Difference Vegetation Index (NDVI) from Sentinel 2 spaceborne observations. Our results indicate that within the fuel break, the PCV of char is 2 × less than it was outside of it (with PCV char declining at a rate of 2% per 3 m into the fuel break). Burn severity is 5 × less, and vegetation health is approximately 3 × greater within the fuel break compared to directly outside. Furthermore, postfire vegetation health was only 1 × less within the fuel break compared to the pre fire condition, whereas it was 5 × less in the surrounding region. The results confirm that the fuel break altered the fire behavior, reducing the fire intensity, thereby proving effective at reducing fire burn severity and preserving vegetation health within the fuel break.

Development of a Radiometric Calibration Method for Multispectral Images of Croplands Obtained with a Remote-Controlled Aerial System

A remote sensing (RS) platform consisting of a remote-controlled aerial vehicle (RAV) can be used to monitor crop, environmental conditions, and productivity in agricultural areas. However, the current methods for the calibration of RAV-acquired images are cumbersome. Thus, a calibration method must be incorporated into RAV RS systems for practical and advanced applications. Here, we aimed to develop a standalone RAV RS-based calibration system without the need for calibration tarpaulins (tarps) by quantifying the sensor responses of a multispectral camera, which varies with light intensities. To develop the standalone RAV-based RS calibration system, we used a quadcopter with four propellers, with a rotor-to-rotor length of 46 cm and height of 25 cm. The quadcopter equipped with a multispectral camera with green, red, and near-infrared filters was used to acquire spectral images for formulating the RAV RS-based standardization system. To perform the calibration study process, libraries of sensor responses were constructed using pseudo-invariant tarps according to the light intensities to determine the relationship equations between the two factors. The calibrated images were then validated using the reflectance measured in crop fields. Finally, we evaluated the outcomes of the formulated RAV RS-based calibration system. The results of this study suggest that the standalone RAV RS system would be helpful in the processing of RAV RS-acquired images.

Drone high resolution infrared imaging of the Lusi mud eruption

The use of low-cost hand-held infrared (IR) thermal cameras based on uncooled micro-bolometer detector arrays became more widespread during the recent years. Thermal cameras have the ability to estimate temperature values without contact and therefore can be used in conditions where targets are difficult or dangerous to reach such as volcanic eruptions. Since May 2006 the Indonesian Lusi mud eruption continues to spew boiling mud, water, aqueous vapour, CO2, CH4 and covers a surface of nearly 7 km2. Here we performed surveys above and around the erupting crater using a specifically equipped remote-controlled aerial vehicle (drone). Despite the harsh logistics and the continuously varying gas concentrations, we managed to collect IR images composing mosaics to estimate the crater zone spatial and temporal thermal variations as well as that in the surrounding regions. In this manuscript we provide a) a description of the main processes that affect and control the acquisition of IR images; b) an overview of still non disclosed physical model used by the thermal camera employed during our survey (i.e. Flir I7 IR); c) a method for capturing high resolution infrared images over an erupting clastic system; d) analysis and interpretation of the acquired data and scientific results. The results show that it is possible to obtain good quality mosaics also in inaccessible areas such as erupting craters where fixed reference points are not constant, and where the presence of IR attenuation factors introduce errors in terms of temperature estimates. However the IR camera radiative transfer model (based on Lowtran model) allows the control of only some of the parameters that affect the attenuation of the IR spectrum. This results in obtained crater temperature estimates up to ∼20% lower than those measured with hand held thermometers, providing, however, very important information about the thermal gradient and the potential radioactive absorption factors. The imaged Lusi vent thermal pattern suggests the presence of shallow convective chambers inside the caldera zone; these are activated by the rise of boiling mud breccia that suddenly cools and sinks. The thermal survey conducted on the dry mud region to the NE of the crater reveals temperatures matching with those measured directly on the field with a hand held thermometer. Here the presence of hot spot anomalies and colder circular features is consistent with the migration of deeper warm fluids along a faulted and fractured area and with widespread pools distribution.

Using Remote Control Aerial Vehicles to Study Variability of Airborne Particulates

Airborne particulates play a significant role in the atmospheric radiative balance and impact human health. To characterize this impact, global-scale observations and data products are needed. Satellite products allow for this global coverage but require in situ validations. This study used a remote-controlled aerial vehicle to look at the horizontal, vertical, and temporal variability of airborne particulates within the first 150 m of the atmosphere. Four flights were conducted on December 4, 2014, between 12:00 pm and 5:00 pm local time. The first three flights flew a pattern of increasing altitude up to 140 m. The fourth flight was conducted at a near-constant altitude of 60 m. The mean PM2.5 concentration for the three flights with varying altitude was 36.3 μg/m3, with the highest concentration occurring below 10 m altitude. The overall vertical variation was very small with a standard deviation of only 3.6 μg/m3. PM2.5 concentration also did not change much throughout the day with mean concentrations for the altitude-varying flights of 35.1, 37.2, and 36.8 μg/m3. The fourth flight, flown at a near-constant altitude, had a lower concentration of 23.5 μg/m3.

Geospatial analysis for conservation: applications with open-source software in the Natural Parks of Barcelona

We describe some applications of geospatial analysis in which open-source software has been prevalent, with the aim of presenting examples of operational use and discussing past and current limitations. The examples are extracted from a sequence of projects carried out in Natural Parks of the Province of Barcelona (Catalonia, NE Spain), including the use of calibrated satellite vegetation index to monitor recovery after fire, multi-criteria analysis to rank abandoned fields for restoration, generalization of vegetation maps using a double-criteria hierarchical clustering, and planning and initial evaluation of aerial campaigns with a small remote-controlled aerial vehicle. Our use of open-source software steadily increased through this sequence of projects, with the R language and environment for statistical computing occupying a central position in our set of tools, but our applications also made use of proprietary software.