Open source R for applying machine learning to RPAS remote sensing images

The increase in the number of remote sensing platforms, ranging from satellites to close-range Remotely Piloted Aircraft System (RPAS), is leading to a growing demand for new image processing and classification tools. This article presents a comparison of the Random Forest (RF) and Support Vector Machine (SVM) machine-learning algorithms for extracting land-use classes in RPAS-derived orthomosaic using open source R packages. The camera used in this work captures the reflectance of the Red, Blue, Green and Near Infrared channels of a target. The full dataset is therefore a 4-channel raster image. The classification performance of the two methods is tested at varying sizes of training sets. The SVM and RF are evaluated using Kappa index, classification accuracy and classification error as accuracy metrics. The training sets are randomly obtained as subset of 2 to 20% of the total number of raster cells, with stratified sampling according to the land-use classes. Ten runs are done for each training set to calculate the variance in results. The control dataset consists of an independent classification obtained by photointerpretation. The validation is carried out(i) using the K-Fold cross validation, (ii) using the pixels from the validation test set, and (iii) using the pixels from the full test set. Validation with K-fold and with the validation dataset show SVM give better results, but RF prove to be more performing when training size is larger. Classification error and classification accuracy follow the trend of Kappa index

Monitoring the understory in eucalyptus plantations using airborne laser scanning

In eucalyptus plantations, the presence of understory increases the risk of fires, acts as an obstacle to forest operations, and leads to yield losses due to competition. The objective of this study was to develop an approach to discriminate the presence or absence of understory in eucalyptus plantations based on airborne laser scanning surveys. The bimodal canopy height profile was modeled by two Weibull density functions: one to model the canopy, and other to model the understory. The parameters used as predictor in the logistic model successfully discriminated the presence or absence of understory. The logistic model composed by gcanopy, gunderstory, and gunderstory showed higher values of accuracy (0.96) and kappa (0.92), which means an adequate classification of presence of understory and absence of understory. Weibull parameters could be used as input in the logistic regression to effectively identify the presence and absence of understory in eucalyptus plantation

Control platform of an unmanned aerial vehicle for the detection of weeds

In the present work, a remote control platform for the stabilization of a drone was developed through trajectory planning with the objective of detecting weeds in a bean field. The weed detection was carried out completely autonomously, using a decision tree as a classification algorithm in the final stage. The results obtained in the evaluation of the performance of the proposed method were satisfactory. The linear regression model between estimated and observed weed densities yielded a coefficient of determination of 0.987 and an average square error of 0.075. Of the total area of the field of study, 84% was estimated with less than 1% coverage of weeds, which indicates a high potential for reducing the volume of applied herbicides. Currently, we are working on automatic control algorithms that detect any anomaly in the flight of the Drones.En el presente trabajo se desarrolló una plataforma de control remota para la estabilización de un Dron mediante la planificación de trayectorias con el objetivo de la detección de malezas en un campo de frijol. La detección de malezas se llevó a cabo de manera completamente autónoma, empleando un árbol de decisión como algoritmo de clasificación en la etapa final. Los resultados obtenidos en la evaluación del desempeño del método propuesto fueron satisfactorios. El modelo de regresión lineal entre las densidades de maleza estimadas y observadas arrojó un coeficiente de determinación de 0.987 y un error cuadrático medio de 0.075. Del área total del campo de estudio, se estimó un 84 % con menos del 1 % de cobertura de malezas, lo cual indica un alto potencial para la reducción del volumen de herbicidas aplicados. Actualmente, estamos trabajando en algoritmos de control automáticos que detecten cualquier anomalía en el vuelo de los Drones

A Low-Cost Method for Collecting Hyperspectral Measurements from a Small Unmanned Aircraft System

Small unmanned aircraft systems (UAS) are a relatively new tool for collecting remote sensing data at dense spatial and temporal resolutions. This study aimed to develop a spectral measurement platform for deployment on a UAS for quantifying and delineating moisture zones within an agricultural landscape. A series of portable spectrometers covering ultraviolet (UV), visible (VIS), and near-infrared (NIR) wavelengths were instrumented using a Raspberry Pi embedded computer that was programmed to interface with the UAS autopilot for autonomous data acquisition. A second set of identical spectrometers were fitted with calibrated irradiance lenses to capture ambient light during data acquisition. Data were collected during the 2017 Great American Eclipse while observing a reflectance target to determine the ability to compensate for ambient light conditions. A calibration routine was developed that scaled raw reflectance data by sensor integration time and ambient light energy. The resulting calibrated reflectance exhibited a consistent spectral profile and average intensity across a wide range of ambient light conditions. Results indicated the potential for mitigating the effect of ambient light when passively measuring reflectance on a portable spectral measurement system. Future work will use multiple reflectance targets to test the ability to classify targets based on spectral signatures under a wide range of ambient light conditions

A Review of Deep Learning Methods and Applications for Unmanned Aerial Vehicles

Deep learning is recently showing outstanding results for solving a wide variety of robotic tasks in the areas of perception, planning, localization, and control. Its excellent capabilities for learning representations from the complex data acquired in real environments make it extremely suitable for many kinds of autonomous robotic applications. In parallel, Unmanned Aerial Vehicles (UAVs) are currently being extensively applied for several types of civilian tasks in applications going from security, surveillance, and disaster rescue to parcel delivery or warehouse management. In this paper, a thorough review has been performed on recent reported uses and applications of deep learning for UAVs, including the most relevant developments as well as their performances and limitations. In addition, a detailed explanation of the main deep learning techniques is provided. We conclude with a description of the main challenges for the application of deep learning for UAV-based solutions