Positional Precision Analysis of Orthomosaics Derived from Drone Captured Aerial Imagery

The advancement of drones has revolutionized the production of aerial imagery. Using a drone with its associated flight control and image processing applications, a high resolution orthorectified mosaic from multiple individual aerial images can be produced within just a few hours. However, the positional precision and accuracy of any orthomosaic produced should not be overlooked. In this project, we flew a DJI Phantom drone once a month over a seven-month period over Oak Grove Cemetery in Nacogdoches, Texas, USA resulting in seven orthomosaics of the same location. We identified 30 ground control points (GCPs) based on permanent features in the cemetery and recorded the geographic coordinates of each GCP on each of the seven orthomosaics. Analyzing the cluster of each GCP containing seven coincident positions depicts the positional precision of the orthomosaics. Our analysis is an attempt to answer the fundamental question, “Are we obtaining the same geographic coordinates for the same feature found on every aerial image mosaic captured by a drone over time?” The results showed that the positional precision was higher at the center of the orthomosaic compared to the edge areas. In addition, the positional precision was lower parallel to the direction of the drone flight

Accuracy Assessment on Drone Measured Heights at Different Height Levels

The advancement in unmanned aerial system (UAS) technology has made it possible to attain an aerial unit, commonly known as a drone, at an affordable price with increasing precision and accuracy in positioning and photographing. While aerial photography is the most common use of a drone, many of the models available in the market are also capable of measuring height, the height of the drone above ground, or the altitude above the mean sea level. On board a drone, a barometer is used to control the flight height by detecting the atmospheric pressure change; while a GPS receiver is mainly used to determine the horizontal position of the drone. While both barometer and GPS are capable of measuring height, they are based on different algorithms. Our study goal was to assess the accuracy of height measurement by a drone, with different landing procedures and GPS settings

Accuracy of Unmanned Aerial System (Drone) Height Measurements

Vertical height estimates of earth surface features using an Unmanned Aerial System (UAS) are important in natural resource management quantitative assessments. An important research question concerns both the accuracy and precision of vertical height estimates acquired with a UAS and to determine if it is necessary to land a UAS between individual height measurements or if GPS derived height versus barometric pressure derived height while using a DJI Phantom 3 would affect height accuracy and precision. To examine this question, height along a telescopic height pole on the campus of Stephen F. Austin State University (SFASU) were estimated at 2, 5, 10 and 15 meters above ground using a DJI Phantom 3 UAS. The DJI Phantom 3 UAS (i.e., drone) was flown up and down the telescopic height pole to estimate height at the 2, 5, 10 and 15 meter locations using four different user controlled flight modes with a total of 30 observations per flight mode. Flight mode configurations consisted of having GPS estimate height while landing the drone between flights, non-GPS mode to estimate height via barometric pressure while landing the drone between flights, flying continuously up and down the height pole while estimating height with GPS on, and flying continuously up and down the height pole in non-GPS mode to estimate height via barometric pressure. A total of 480 height measurements were recorded (30 measurements per height interval per all four flight mode combinations). Standard deviation results indicated that height measurements taken with the drone were less precise when landing was not reset between measurements. Root mean square error (RMSE) analysis indicated that having the landing reset without GPS on achieved the highest accuracy of all measurements taken. An ANOVA conducted on the absolute errors reconfirmed that having the landing reset before each height measurement using the drone achieved higher accuracy compared to flying the drone continuously. This indicates the practical application of height measurement of the DJI Phantom 3 UAS and the importance of resetting the UAS before each height measurement

Accuracy of Unmanned Aerial System (Drone) Height Measurements

Vertical height estimates of earth surface features using an Unmanned Aerial System (UAS) are important in natural resource management quantitative assessments. An important research question concerns both the accuracy and precision of vertical height estimates acquired with a UAS and to determine if it is necessary to land a UAS between individual height measurements or if GPS derived height versus barometric pressure derived height while using a DJI Phantom 3 would affect height accuracy and precision. To examine this question, height along a telescopic height pole on the campus of Stephen F. Austin State University (SFASU) were estimated at 2, 5, 10 and 15 meters above ground using a DJI Phantom 3 UAS. The DJI Phantom 3 UAS (i.e., drone) was flown up and down the telescopic height pole to estimate height at the 2, 5, 10 and 15 meter locations using four different user controlled flight modes with a total of 30 observations per flight mode. Flight mode configurations consisted of having GPS estimate height while landing the drone between flights, non-GPS mode to estimate height via barometric pressure while landing the drone between flights, flying continuously up and down the height pole while estimating height with GPS on, and flying continuously up and down the height pole in non-GPS mode to estimate height via barometric pressure. A total of 480 height measurements were recorded (30 measurements per height interval per all four flight mode combinations). Standard deviation results indicated that height measurements taken with the drone were less precise when landing was not reset between measurements. Root mean square error (RMSE) analysis indicated that having the landing reset without GPS on achieved the highest accuracy of all measurements taken. An ANOVA conducted on the absolute errors reconfirmed that having the landing reset before each height measurement using the drone achieved higher accuracy compared to flying the drone continuously. This indicates the practical application of height measurement of the DJI Phantom 3 UAS and the importance of resetting the UAS before each height measurement

Digital Preservation and Access of Natural Resources Documents

Digitization and preservation of natural resource documents were reviewed and the current status of digitization presented for a North American university. It is important to present the status of the digitation process for natural resources and to advocate for increased collections of digital material for ease of reference and exchange of information. Digital collections need to include both published documents and ancillary material for research projects and data for future use and interpretation. The methods in this paper can be applied to other natural resource collections increasing their use and distribution. The process of decision making for documents and their preservation and inclusion in ScholarWorks is presented as a part of the Forest Sciences Commons as a subset of the Life Sciences Commons of the Digital Commons Open Network launched and maintained by bepress. Digitization has increased the roles and skillsets needed for librarians and from libraries. This creates new challenges and opportunities for the library as publisher and as an advocate for open access. Digital curation melds together digitization and knowledge management and enhances community engagement. Digitization of collections are reviewed and natural resource documentation presented for faculty publications, Research Projects and Centers, eBooks, Journals, Galleries and electronic Theses and Dissertations (ETDs). Recommendations are made to increase the digital curation of the collection by encouraging community participation and use. Digital archives are important to natural resource professionals as society-ready natural resource graduates need to deal effectively with complex ecological, economic and social issues of current natural resources management. Natural resource research for the future needs to ensure that professionals have a greater breath of knowledge as they interpret and apply new knowledge, understanding, and technology to complex, transdisciplinary social and biological issues and challenges

Praxis der Datenerfassung mit Drohnen für GIS und Vermessung

In der Vorbereitung zur Bauphase von Projekten ist die Visualisierung sowie die Erfassung tagesaktueller Naturstandsdaten ein gewichtiger Aspekt. Bilder von Online-Karten, die via Satellit oder Flugzeug erstellt wurden, können bis zu mehreren Jahren alt sein. Drohnen mit Kameras bestückt können Gebiete gezielt befliegen und nach anschließender Auswertung werden die Daten zur Vermessung und Visualisierung herangezogen. Mit Hilfe der drohnengestützten Photogrammmetrie werden so digitale Karten, Geländemodelle, 3D Modelle rasch und tagesaktuell generiert. Ein wesentlicher Faktor stellt die weitere Integration der Daten in Verwaltungssysteme dar. Die generierten Pläne können in einer Verwaltungssoftware und/oder einer GIS Software direkt verarbeitet werden. Der administrative Aufwand, bei der Verortung von Sachdaten, wird dabei nicht nur durch die Visualisierung erheblich verringert. Beispielsweise soll hier die Digitalisierung von Friedhöfen genannt werden, die durch diese Technologie kostengünstig und rasch realisiert werden kann. Die durch Drohnenbefliegung generierten 3D Volumenmodelle von Steinbrüchen sind nicht nur für Visualisierungen interessant, sondern die daraus gewonnenen Höhenschichtmodelle, digitalen Gelände- oder Oberflächenmodelle dienen auch Vermessungen und sind Behördenkonform. Die Befliegung mit Flugrobotern, mit anschließender photogrammetrischer Auswertung, bietet mit Orthofotos, 3D Modellen und Luftbildern meist eine kostengünstig Alternative gegenüber der terrestrischen Vermessung. Das verwendete uLFZ (unbemannte Luftfahrzeug) muss von der Flugsicherungsbehörde (ACG = Austro Control) für den Betrieb zugelassenen werden, sowie der Pilot die entsprechende Befähigung nachweisen

Integrating Hands-On Undergraduate Research in an Applied Spatial Science Senior Level Capstone Course

A senior within a spatial science Ecological Planning capstone course designed an undergraduate research project to increase his spatial science expertise and to assess the hands-on instruction methodology employed within the Bachelor of Science in Spatial Science program at Stephen F Austin State University. The height of 30 building features estimated remotely with LiDAR data, within the Pictometry remotely sensed web-based interface, and in situ with a laser rangefinder were compared to actual building feature height measurements. A comparison of estimated height with actual height indicated that all three estimation techniques tested were unbiased estimators of height. An ANOVA, conducted on the absolute height errors resulting in a p-value of 0.035, concluded the three height estimating techniques were statistically different at the 95% confidence interval. A Tukey pair-wise test found the remotely sensed Pictometry web-based interface was statistically more accurate than LiDAR data, while the laser range finder was not different from the others. The results indicate that height estimates within the Pictometry web-based interface could be used in lieu of time consuming and costly in situ height measurements. The findings also validate the interactive hands-on instruction methodology employed by Geographic Information Systems faculty within the Arthur Temple College of Forestry and Agriculture in producing spatial science graduates capable of utilizing spatial science technology to accurately quantify, qualify, map, and monitor natural resources

Merging GPS Data with High Spatial Resolution Multispectral Imagery: An Urban Recreation Case Study

In 1992 a disc golf course was created by Alpha Phi Omega, Nu Sigma Chapter of Stephen F. Austin State University within Pecan Park in the c ity of Nacogdoches, Texas. Using constructs from Landscape Ecology, in cluding structure, function and change within a land mosaic provided the basis for establishment of the course. The addition of the disc golf cour se modified the use of the park promoting cultural cohesion among the disc golf enthusiasts. To aid the recreational enjoyment of golf participants, vector m aps of each fairway were created when the disc course was developed and loca ted at the start of each hole. In the fall of 2006, with the advent of hig h spatial resolution multispectral digital imagery, 6 inch spatial resolution multisp ectral imagery were used as a base map to create fine detail maps representing each disc golf basket and tee with GPS collected fairway data. A kiosk map rep resenting the entire course was created so each participant could orient thems elves prior to playing each round of disc golf. By incorporating high spatial resolution imagery with GPS collected fairway locations, and using spatial analysis to calculate the absolute distance from a golf tee to each respecti ve basket, we were able enhance the recreational and educational enjoyment of each golf participant