Accuracy Analysis of a 3D Model of Excavation, Created from Images Acquired with an Action Camera from Low Altitudes

Abstract

In the last few years, Unmanned Aerial Vehicles (UAVs) equipped with compact digital cameras, have become a cheap and efficient alternative to classic aerial photogrammetry and close-range photogrammetry. Low-altitude photogrammetry has great potential not only in the development of orthophoto maps but is also increasingly used in surveying and rapid mapping. This paper presents a practical aspect of the application of the custom homemade low-cost UAV, equipped with an action camera, to obtain images from low altitudes and develop a digital elevation model of the excavation. The conducted analyses examine the possibilities of using low-cost UAVs to deliver useful photogrammetric products. The experiments were carried out on a closed excavation in the town of Mince (north-eastern Poland). The flight over the examined area was carried out autonomously. A photogrammetric network was designed, and the reference areas in the mine were measured using the Global Navigation Satellite System-Real Time Kinematic (GNSS-RTK) method to perform accuracy analyses of the excavation 3D model. Representation of the created numerical terrain model was a dense point cloud. The average height difference between the generated dense point cloud and the reference model was within the range of 0.01–0.13 m. The difference between the volume of the excavation measured by the GNSS kinematic method and the volume measured on the basis of a dense point cloud was less than 1%. The obtained results show that the application of the low-cost UAV equipped with an action camera with a wide-angle lens, allows for obtaining high-accuracy images comparable to classic, compact digital cameras.

Measuring Change Using Quantitative Differencing of Repeat Structure-From-Motion Photogrammetry: The Effect of Storms on Coastal Boulder Deposits

“…The ultra-wide-angle (fisheye) lenses mounted on the popular consumer camera brand GoPro capture a~120 • field of view, but have barrel distortion due to their short focal length. Despite their limitations, GoPro cameras are popular tools for acquiring UAV imagery [24,31,[58][59][60], they are relatively inexpensive, are light enough to be carried by off-the-shelf consumer drones, offer good resolution for their size, and can image large areas at relatively low altitudes (where lower wind speeds make UAV operation easier) [58,[61][62][63][64]. However, ultra-wide-angle lenses require substantial calibration and correction to correct the inherent barrel distortion [33,59].…”

Multi-Variant Accuracy Evaluation of UAV Imaging Surveys: A Case Study on Investment Area

“…96% of the height differences are related to ΔZ ≤ 0.05 m and only ca. 4% are outliers ΔZ > 0.05 m. Oniga et al [55] compared results with terrestrial laser scanning (TLS) data and obtained a standard deviation equal to 0.098 m. Wierzbicki and Nienaltowski [42] created the triangulated irregular network (TIN) model based on points measured using the GNSS RTK technique, and they achieved a standard deviation of 0.090 m for height differences. To avoid the interpolation of the irregular shape of the ground, our study contains height differences only for points measured in the field.…”

“…However, in our opinion, the operational use of UAV imagery acquired by means of single-lens reflex or compact system camera instead of medium or large format aerial digital cameras for data collection in order to undertake large-scale basic, thematic [39,40,41,42] and inventory mapping is one of the fundamental issues for the application of UAVs in geomatics and in particular in geodesy. For example, in Germany, the USA and also in Poland, there are no detailed technical guidelines regarding the use of UAV imagery in geodetic surveys.…”

“…According to the authors’ knowledge, the complex accuracy assessment of the computing pipeline of particular photogrammetric products (bundle-block adjustment with camera self-calibration, dense point cloud, digital surface model and orthomosaic) which we present in this paper, do not exist at present. Current studies concerning the accuracy assessment of UAV photogrammetric products are realized in incomparable technical conditions of projects and with the use of various statistical parameters of results assessment [39,40] relating to the particular stages of the processing [36,41,42,51]. The most commonly used metrical information of accuracy were root mean square errors RMSE (XYZ) on ground control and check points, which characterized bundle block adjustment results.…”

A New Adaptive Method for the Extraction of Steel Design Structures from an Integrated Point Cloud

“…The authors indicate that laser technology had clear advantages over photogrammetric models in situations where vegetation can be a problem during terrain surface reconstruction. In contrast, in the case of terrains not covered by vegetation, UAV photogrammetry enables the achievement of surface model determination accuracy from 1 cm [ 29 ].…”