Evaluating the effectiveness of UAV imaging in the accuracy of corridor maps

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Evaluating the effectiveness of UAV imaging in the accuracy of corridor maps

ارائه دهنده: Provider: Reza zerafaty jamal

اساتید راهنما: Supervisors: Dr morteza heydari muzaffar

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: Dr Hassan khotanlu _Dr Hossein Tarabzadeh Khorasani

زمان و تاریخ ارائه: Time and date of presentation: 7september 2022

مکان ارائه: Place of presentation: Faculty of Engineering

چکیده: Abstract: The production of topographic maps by drone photogrammetry has replaced traditional mapping in many civil projects. UAV photogrammetry due to rapid development of hardware and software, it can be used in many geomatic applications including agriculture, forestry, archeology and architecture, emergency management and traffic monitoring. Nowadays, in mapping the boundaries of linear projects such as: roads, water transmission canals, power transmission lines (electricity and gas), railway lines and the like, is done by UAV photogrammetry. UAV photogrammetry has emerged as a viable alternative due to its lower cost, greater spatial and temporal resolution, and flexibility in capturing images compared to other conventional aerial and space methods. Assessing and ensuring accuracy is very important for topographic maps. Knowledge of the number and distribution of control points throughout the project area and the optimal imaging method are effective in producing these maps. In this paper, in order to achieve the most optimal imaging mode and the highest accuracy in the production of topographic maps of this type of projects, the effects of flight design parameters, number and distribution of control points were studied. Also, the effect of using accurate positioning equipment of image centers on reducing the number of required control points has been investigated. Image processing without accurate information of image centers with control points, image processing with accurate information of image centers and without using control points and image processing with accurate information of image centers and control points, were considered in two flight modes with fixed altitude and fixed scale. Of the 25 points whose exact coordinates were measured differentially by the Global Positioning System, 18 were ground control points and 7 were check points. The control of the elevation coordinates of the points was performed using the direct geometric leveling method. To evaluate the accuracy of the results, the amount of error and the accuracy of the work performed, the leveling operation was performed in a round trip between all control and check points. Evaluating the accuracy of UAV photogrammetric method in producing topographic maps related to this project, according to the criterion, the root mean square of errors have been done for the control and check points. In addition to calculating this criterion for control and checkpoints, the difference between the digital models prepared and the reference model was considered as another criterion for comparison and evaluation. According to the results, the mean height error of all points in the constant-scale mode has the lowest value in Scenario 3. The numerical value of the mean error in this case was equal to 0.010172 meters for control points and 0.0202 meters for check points. The accuracy of the models obtained from point clouds with dimensions of 0.5 meters is higher than the point clouds of 2 and 4 meters. The largest difference from the reference model is related to model 1 in the category of models obtained from 0.5 meter point clouds, which varies numerically in the range (-1.68 to 10.56) meters. The results of the height error evaluation of control and check points show if in aerial triangulation and justification of images use image center observations alone, in challenging projects the mapping of linear areas where the mapping is done in a strip area will not have the desired accuracy. The use of ground reference images alone is not sufficient and the simultaneous use of ground control points and ground reference images improves the accuracy of the results. As a result, the use of ground control points, fixed scale images, and image center information in the image processing process to produce corridor maps provides the best elevation accuracy compared to other modes. Also, the use of the initial digital elevation model of the project area in performing flight operations and capturing images with fixed scales has a significant effect on increasing the accuracy of the elevation component. Based on the comparison of the final digital elevation models compared to the reference model, the accuracy of the models obtained from the resolution of 0.5 meters is higher than 2 and 4 meters. Also, the effectiveness of filters to correct and reduce errors in digital elevation models has better results

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