Unmanned Aerial System (UAS) is getting to be the most important technique in recent days for precision agriculture and High Throughput Phenotyping (HTP). Attributes of sorghum panicle, especially, are critical information to assess overall crop condition, irrigation, and yield estimation. In this study, it is proposed a method to extract phenotypes of sorghum panicles using UAS data. UAS data were acquired with 85% overlap at an altitude of 10m above ground to generate super high resolution data. Orthomosaic, Digital Surface Model (DSM), and 3D point cloud were generated by applying the Structure from Motion (SfM) algorithm to the imagery from UAS. Sorghum panicles were identified from orthomosaic and DSM by using color ratio and circle fitting. The cylinder fitting method and disk tacking method were proposed to estimate panicle volume. Yield prediction models were generated between field-measured yield data and UAS-measured attributes of sorghum panicles.
Field-based high-throughput phenotyping is a bottleneck to future breeding advances. The use of remote sensing with
unmanned aerial vehicles (UAVs) can change the way agricultural research operates by increasing the spatiotemporal
resolution of data collection to monitor status of plant growth. A fixed-wing UAV (Tuffwing) was operated to collect
images of a sorghum breeding research field with 70% overlap at an altitude of 120 m. The study site was located at Texas
A and M AgriLife Research’s Brazos Bottom research farm near College Station, Texas, USA. Relatively high-resolution
(>2.7cm/pixel) images were collected from May to July 2017 over 880 sorghum plots (including six treatments with four
replications). The collected images were mosaicked and structure from motion (SfM) calculated, which involves
construction of a digital surface model (DSM) by interpolation of 3D point clouds. Maximum plant height for each
genotype (plot) was estimated from the DSM and height calibration implemented with aerial measured values of groundcontrol
points with known height. Correlations and RMSE values between actual height and estimated height were
observed over sorghum across all genotypes and flight dates. Results indicate that the proposed height calibration method
has a potential for future application to improve accuracy in plant height estimations from UAVs.
The objective of this research is to develop a novel machine learning framework for automatic cotton genotype selection using multi-source and spatio-temporal remote sensing data collected from Unmanned Aerial System (UAS). The proposed machine learning model is based on Artificial Neural Network (ANN) and it takes UAS based multi-temporal features such as canopy cover, canopy height, canopy volume, Normalized Difference Vegetation Index (NDVI), Excessive Greenness Index along with non-temporal features such as cotton boll count, boll size and boll volume as input and predicts the corresponding yield. Testing the performance of our model using actual yield resulted in an R square value of approximately 0.9. The proposed cotton genotype selection model is expected to revolutionize the cotton breeding research by providing valuable tools to cotton breeders so that they can not only increase their experiment size for faster genotype selection but also make efficient and informed decision on best performing genotype selection.
Land leveling is the initial step for increasing irrigation efficiencies in surface irrigation systems. The objective of this paper was to evaluate potential utilization of an unmanned aerial system (UAS) equipped with a digital camera to map ground elevations of a grower’s field and compare them with field measurements. A secondary objective was to use UAS data to obtain a digital terrain model before and after land leveling. UAS data were used to generate orthomosaic images and three-dimensional (3-D) point cloud data by applying the structure for motion algorithm to the images. Ground control points (GCPs) were established around the study area, and they were surveyed using a survey grade dual-frequency GPS unit for accurate georeferencing of the geospatial data products. A digital surface model (DSM) was then generated from the 3-D point cloud data before and after laser leveling to determine the topography before and after the leveling. The UAS-derived DSM was compared with terrain elevation measurements acquired from land surveying equipment for validation. Although 0.3% error or root mean square error of 0.11 m was observed between UAS derived and ground measured ground elevation data, the results indicated that UAS could be an efficient method for determining terrain elevation with an acceptable accuracy when there are no plants on the ground, and it can be used to assess the performance of a land leveling project.