Research on the influence of flight parameter settings on UAV photogrammetric modeling
[Objective]With the continuous advancement of digital infrastructure construction and the flourishing development of digital cities,unmanned aerial vehicle(UAV)photogrammetric modeling technology is rapidly emerging.However,because of the differences in the number of photos taken and the shooting angles,the model often exhibits certain phenomena,such as holes and distortions,leading to a decrease in model accuracy.Moreover,excessive image overlap can lead to redundant image information,which results in modeling algorithms being unable to accurately identify and match feature points,thereby reducing modeling accuracy and reliability and negatively affecting modeling effectiveness.In addition,the high overlap rate leads to data redundancy,increases data processing time and cost,and reduces modeling efficiency.How to improve model accuracy while balancing modeling efficiency has received widespread attention.[Methods]This study regarded the Honghui Cultural and Sports Complex Building of Fuzhou University as the experimental object and selected three flight parameters,namely image overlap ratio,margin setting,and flight speed.By recording relevant data,such as the duration of UAV field photography flight,aerial triangulation time,duration of 3D modeling,and model size,the relationship between UAV flight parameter setting,model accuracy,and modeling efficiency was investigated to determine the optimal flight parameter setting for modeling efficiency.The experiment used the method of controlling variables to reduce the impact of secondary factors.To avoid the impact of light and shadow changes on modeling,the field data collection time was scheduled from 10 AM to 3 PM on cloudy days.In terms of duration calculation,to avoid human interference,only objective automatic operation time was calculated,that is,the flight duration of the UAV(from takeoff to shooting to landing),the aerial triangulation time,and the duration of 3D modeling were calculated,and all three duration statistical data were displayed in the software.All experimental data needed to be tested twice and averaged to ensure the accuracy of the results.If there was a significant difference between the two test data,then the experiment was repeated and the most similar data were selected from the three similar groups to calculate the average value to avoid the impact of errors on the experimental data.Six sets of experiments were conducted in this research,with the first group searching for the relationship between image overlap ratio and modeling efficiency on a large scale and the second and third groups searching for the relationship between flight speed,margin setting,and modeling efficiency based on the first group.The fourth,fifth,and sixth groups optimized the image overlap ratio span considering speed and margin conditions,gradually narrowed the experimental range,and compared the data to determine the optimal modeling efficiency.[Results]Results showed that UAV has the optimal modeling efficiency when the sideward overlap rate is 53％,the heading overlap rate is 53％,the flight speed is 9.3 m\s,and the margin setting is automatic.The image overlap ratio complies with the relevant regulations in the technical specifications for oblique digital aerial photography(GB/T 39610-2020)and the specifications for inspection and acceptance of the quality of three-dimensional model data products on geographical information(CH/T 9024-2014).[Conclusions]As an important technical support for digital infrastructure construction,UAV photogrammetric modeling provides new avenues for urban planning,environmental monitoring,power inspection,disaster assessment,and other fields.The experimental results of this research achieve the expected goal,enhance the efficiency of UAV photogrammetric modeling,and improve model accuracy.
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