A comparative analysis of georeferencing techniques for crop canopy height estimation using UAS photogrammetry

Simple item page
dc.contributor.advisorStarek, Michael
dc.contributor.advisorBhandari, Mahendra
dc.contributor.authorLandivar Scott, Jose Luis
dc.contributor.committeeMemberChu, Tianxing
dc.creator.orcidhttps://orcid.org/0000-0002-6327-6093
dc.date.accessioned2024-01-05T22:48:40Z
dc.date.available2024-01-05T22:48:40Z
dc.date.issued2023-08
dc.descriptionA thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Geospatial Systems Engineeringen_US
dc.description.abstractIn the rapidly evolving fields of geospatial engineering and precision agriculture, the accuracy and reliability of georeferencing techniques and Uncrewed Aircraft System (UAS) methodologies are crucial for effective decision-making and crop management. This research aims to enhance UAS Structure-from-Motion (SfM) photogrammetry data quality for crop canopy height estimation in high-throughput phenotyping. The study investigates and compares the accuracy and reliability of three distinct methods used for georeferencing of the UAS imagery, which subsequently enables more accurate SfM 3D reconstruction: Global Navigation Satellite System (GNSS) without any correction aiding (GNSS-only), GNSS+Real-Time Kinematic (RTK), receiving RTK corrections from a local base station, GNSS+Real-Time Network (RTN), receiving RTK corrections from the Texas Department of Transportation (TxDOT) GNSS reference station network. The study further assesses the correlation between manually measured plant heights and those estimated from UAS-SfM point cloud data, exploring three different Digital Terrain Model (DTM) generation techniques. The research was conducted at the Texas A&M AgriLife Research and Extension Center in Corpus Christi, Texas, USA, on corn crops grown during the 2022 agricultural season. The three DTM generation methods under consideration included 1) using a DTM acquired from a flight conducted before plant emergence, 2) creating a DTM by interpolating ground height points, and 3) implementing automatic classification algorithms. Findings initially revealed that the GNSS+RTK method consistently outperformed the other georeferencing techniques, delivering more accurate results across various dates. Despite these overall trends, there were some instances where the GNSS+RTK method did not consistently outperform the other techniques. The use of one ground control point (GCP) improved georeferencing accuracy compared to scenarios with no GCPs used, while GNSS-only without correction aiding reported the least accurate results as expected. Regarding plant height estimation, the highest accuracy was generally achieved with greater canopy cover percentages, with the optimal percentage varying depending on the data collection date and DTM creation method. The highest coefficient of determination (R2) of 0.92 between manual measurements and UAS-SfM derived plant heights was found when the DTM was either interpolated from ground height points or obtained from a pre-emergence flight.en_US
dc.description.collegeCollege of Scienceen_US
dc.description.departmentGeospatial Surveying Engineeringen_US
dc.format.extent86 pagesen_US
dc.identifier.urihttps://hdl.handle.net/1969.6/97724
dc.language.isoen_USen_US
dc.rightsAttibution-NoDerivs 4.0 International (CC BY-ND 4.0)en_US
dc.rights.urihttps://creativecommons.org/licenses/by-nd/4.0/*
dc.titleA comparative analysis of georeferencing techniques for crop canopy height estimation using UAS photogrammetryen_US
dc.typeTexten_US
dc.type.genreThesisen_US
thesis.degree.disciplineGeospatial Surveying Engineering
thesis.degree.grantorTexas A & M University--Corpus Christien_US
thesis.degree.levelMastersen_US
thesis.degree.nameMaster of Scienceen_US

Files

Original bundle

Now showing 1 - 1 of 1
Thumbnail Image
Name:
Landivar Scott_Jose_Thesis.pdf
Size:
6.59 MB
Format:
Adobe Portable Document Format
Download

Collections

Theses