A PROMPT METHODOLOGY TO GEOREFERENCE COMPLEX HYPOGEA ENVIRONMENTS

Latest Developments in Reality-Based 3D Surveying and Modelling, 2018

Nowadays, the increasing computation power of commercial grade processors has actively led to a vast spreading of image-based reconstruction software as well as its application in different disciplines. As a result, new frontiers regarding the use of photogrammetry in a vast range of investigation activities are being explored. This paper investigates the implementation of fisheye lenses in non-classical survey activities along with the related problematics. Fisheye lenses are outstanding because of their large field of view. This characteristic alone can be a game changer in reducing the amount of data required, thus speeding up the photogrammetric process when needed. Although they come at a cost, field of view (FOV), speed and manoeuvrability are key to the success of those optics as shown by two of the presented case studies: the survey of a very narrow spiral staircase located in the Duomo di Milano and the survey of a very narrow hypogea structure in Rome. A third case study, which deals with low-cost sensors, shows the metric evaluation of a commercial spherical camera equipped with fisheye lenses.

The progress in modern technologies such as precise lightweight cameras mounted on unmanned aerial vehicles (UAV) and the more user-friendly software in the photogrammetric field, allows for 3-D model construction of any structure or shape. Software now achieves in sequence the processes of matching, generating tie points, block bundle adjustment, and generating digital elevation models. The aim of this study is to make a virtual 3-D model of the college of engineering /University of Duhok. Kurdistan Region, Iraq. The data input is vertical and oblique imagery acquired by UAV, ground control points distributed on the surrounded ground, facades, and roof. Ground control points were measured by the GPS RTK system in addition to the reflectorless total station instrument. The data is processed mainly using Agisoft PhotoScan software as well as the Global Mapper and the ReCap software. The output is a 3-D model, digital elevation model, and orthomosaic. Geometric and visual inspections were carried out. Some imperfections appeared on the sharp edges and parapets of the building. In the geometric accuracy of selected Journal of Engg. Research Online First Article 2 points on the building, the maximum standard deviation in the coordinates was ±4cm.

The paper reports on photogrammetric and geodetic surveying for control measurements of historical buildings that are located in the neighbourhood of a large tunnel construction in the city of Bremen, Germany. The tunnel is about 800m long and 30m wide, and it is currently built by slotted wall method. Due to the ditch depth of about 20m it is likely that adjacent buildings might get significant deformations or damages which then have to be compensated financially. In this situation a three-dimensional object survey has to be performed that includes image documentation of damages. A total of 10 buildings had to be observed. The required object accuracy of ±1mm has been successfully achieved.

The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2018

Narrow spaces and passages are not a rare encounter in cultural heritage, the shape and extension of those areas place a serious challenge on any techniques one may choose to survey their 3D geometry. Especially on techniques that make use of stationary instrumentation like terrestrial laser scanning. The ratio between space extension and cross section width of many corridors and staircases can easily lead to distortions/drift of the 3D reconstruction because of the problem of propagation of uncertainty. This paper investigates the use of fisheye photogrammetry to produce the 3D reconstruction of such spaces and presents some tests to contain the degree of freedom of the photogrammetric network, thereby containing the drift of long data set as well. The idea is that of employing a multi-camera system composed of several fisheye cameras and to implement distances and relative orientation constraints, as well as the precalibration of the internal parameters for each camera, within the bundle adjustment. For the beginning of this investigation, we used the NCTech iSTAR panoramic camera as a rigid multi-camera system. The case study of the Amedeo Spire of the Milan Cathedral, that encloses a spiral staircase, is the stage for all the tests. Comparisons have been made between the results obtained with the multicamera configuration, the auto-stitched equirectangular images and a data set obtained with a monocular fisheye configuration using a full frame DSLR. Results show improved accuracy, down to millimetres, using a rigidly constrained multi-camera.

Demand of Virtual 3D City models is increasing day by day for various engineering and non-engineering fields. Now a day, various methods are available to create Virtual 3D City models. Photogrammetric method is one of the main method to create virtual 3D City model, because of many advantages. In Photogrammetric method, data acquisition is a main and important step for 3D City modeling. So Video recording is an easy way to capture the large city area in less time. From this video data image frame creates and identified the suitable image frames for close range photogrammetric processing. Thus a good multi camera setup is a very efficient tool for city data capture. In this work, we developed a multi camera setup for capture the video of a city or any area. After capturing the data, Camera calibration is also a important issue. So we also develop a simple method for multi camera setup calibration by using video data.

ISPRS International Journal of Geo-Information, 2019

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...

The research illustrated in this article aimed at identifying a good standard methodology to survey very narrow spaces during 3D investigation of Cultural Heritage. It is an important topic in today's era of BIM modelling applied to Cultural Heritage. Spaces like staircases, corridors and passages are very common in the architectural or archaeological fields, and obtaining a 3D-oriented survey of those areas can be a very complex task when completeness of the model and high precision are requested. Photogrammetry appears to be the most promising solution in terms of versatility and manoeuvrability also considering the quality of the required data. Fisheye lenses were studied and tested in depth because of their significant advantage in the field of view if compared with rectilinear lenses. This advantage alone can be crucial to reduce the total amount of photos and, as a consequence, to obtain manageable data, to simplify the survey phase and to significantly reduce the elaboration time. In order to overcome the main issue that arise when using fisheye lenses, which is the lack of rules that can be employed to design the survey, a general mathematical formulation to precisely estimate the GSD (Ground Sampling Distance) for every optical projection is presented here. A complete survey of a real complex case study was performed in order to test and stress the proposed methodology, and to handle a fisheye-based survey from beginning to end: the photogrammetric survey of the Minguzzi Staircase. It is a complex service spiral-staircase located in the Duomo di Milano with a total height of 25 meters and characterized by a narrow walkable space about 70 centimetres wide.

The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XLVI-2/W1-2022 9th Intl. Workshop 3D-ARCH “3D Virtual Reconstruction and Visualization of Complex Architectures”, 2–4 March 2022, Mantua, Italy, 2022

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.

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2019

This paper reports the results of an experiment that aims at the virtual reconstruction of a urban site that has been partially reshaped during the 20th century; the reconstruction process is based on period photos. The chosen case study is the eldest harbour of Palermo, named 'Cala'; the site was bombed during World War II and new buildings took the place of the ruined ones. Two period photos, taken from an aircraft, document the buildings that were destroyed by bombs. The 3D restitution process used the 'inverse' projection from period photos (2D) to the virtual space (3D) ; the first step was therefore addressed to the calculation of the inner parameters (focal length, principal point coordinates) and of the cameras' pose, i.e. their position and orientation. The data needed for these calculations were extracted from the 3D laser scanning survey of those buildings that appear in photos and that are still on site. The calculation of inner parameters and poses has been computed with a motion tracking commercial package. The second part of the paper focuses a process for the fruition of virtual reconstructions, based on the alignment of real panoramic images, generated by photos taken on site, and of virtual panoramic images, extracted from the 3D reconstruction model; the proposed method uses SfM photogrammetric tools.

IEEE Access

This work was supported in part by the Basque Government through BIKAINTEK2018 program and CAF Signalling. In collaboration between Ikerlan, CAF Signalling and Mondragon Unibertsitatea. We would also like to thank Euskotren and Eusko Trenbide Sarea.