Handheld Fisheye Multicamera System: Surveying Meandering Architectonic Spaces in Open-Loop Mode – Accuracy Assessment

Abstract

Abstract. The task of digitalizing meandering complex spaces in 3D is a challenging one even with the most advanced instrumentation like lightweight terrestrial laser scanner or portable/wearable Mobile Mapping Systems (MMSs). The complexity and extension of architectonic spaces such as staircases, corridors and passages are such that the acquisition time using static devices becomes prohibitive and the accuracy using mobile devices gets affected by drift error leading to warped models or requiring abundant control measurements. This paper presents a photogrammetric portable fisheye multicamera solution for the 3D survey of complex areas that aims at being both handy and fast in the acquisition as well as more reliable ad accurate than common MMSs. The paper showcases a stress test conducted on five complex reconstruction trajectories selected from the meandering connection passages of Milan’s Cathedral. The tests are constructed as worst-case scenario to evaluate the accuracy and drift error amount of the proposed system in open-ended unconstrained paths. The results, though still suffering from moderate drift error, highlights the potential of the solution, especially in retaining the overall shape and orthogonality of the architectonic elements acquired.

Rapid and Low-Cost Photogrammetric Survey of Hazardous Sites, From Measurements to Vr Dissemination

“…2.1.1 Robust to drift error, even in the absence of GCPs, the multi-camera can deliver results free from noticeable distortions or bends. Based on previous tests (Perfetti et al, 2022a), for the longer tunnels (~ 150m) the expected maximum drift error in these environments is from 5cm to 15cm.…”

“…The device mounts five cameras employing fisheye lenses and a global shutter sensor and three illuminators. The multi-camera has an omnidirectional angle of view that is therefore able to frame in a single take the entire environment except for the portion occupied by the operator (Perfetti et al 2022a). Ant3D has demonstrated in previous tests that it is capable of capturing complex and tortuous environments in short times and that it can guarantee architectural-range accuracy of 2-3cm with the use of Ground Control Points (GCPs) and drift of about 5-10cm for every 100m for unconstrained trajectories (Marotta et al, 2022;Perfetti et al, 2022a;Perfetti et al, 2022b).…”

Lidar Imms vs Handheld Multicamera System: A Stress-Test in a Mountain Trailpath

“…The second tool used in the comparison is a prototype of a photogrammetric multicamera developed for rapid, on-the-move 3D surveying of confined and elongated spaces, such as tunnels, galleries, passages, corridors, caves, and forest trails called Ant3D (Perfetti and Fassi, 2022; patent pending N. 102021000000812). The device consists of a hand-held instrument housing five cameras with fisheye lenses, and a backpack housing a computer and the battery for the system.…”

“…Figure 4 shows an image of the multicamera device while Table 4 reports the main technical information of the system. Perfetti and Fassi (2022), initial values for the internal orientation parameters, previously obtained in the laboratory, were provided as input to the software and the calibrated distances between the cameras were imposed as constraints using the "scalebar" function of the software. Once the Structure from Motion (SfM) was finished and the correctness of the orientation of the images was visually checked, dense point clouds were produced with the same software.…”

“…Troisi et al (2017) showed the effective use of fisheye photogrammetry using frames extracted from video sequences to survey an extensive underground tunnel environment with the goal of locating a point at the very end, no constraints were used along the path, they report a positioning error of around 7 m for a 1 km long trajectory. While Perfetti and Fassi (2022) presented a test carried out with a handheld fisheye multicamera system to survey extensive confined spaces where they evaluated the drift error resulted from several open-loop acquisitions, the results reported a drift of around 4-5 cm for every 100 m of acquisition. This shows that the accuracy achievable employing image-based solution exceeds the accuracy reported in the literature from IMMS, However, the characteristics of the produced PC often do not meet the requirements in terms of noise and completeness of the data over long ranges, since the quality of the PC produced by dense image-matching is dependent on: (i) image quality, i.e.…”