![]() ![]() In the case of the ToF camera is kept in the stationary position during data acquisition, some differences usually occur between the measurements (frames) recorded from the same scene. All frames acquired sequentially are recorded in separate measurement files. The origin of the coordinates is the optical axis and overlaps the camera frontal plane ( Figure 4). The coordinates (xyz), the amplitude, and confidence values are recorded into the measurement files. The SR4000 camera records 50 frames per second (fps). ![]() The imaging sensor has size 144 × 176 pixels and the measurement error is 1 cm on its maximum measurement range of 5 m. It has size 65 mm × 65 mm × 68 mm and weight of 470 g. Very often a camera is integrated into a TLS instrument to allow the contemporary recording of 3-D shape and color information.Ī SwissRanger ® SR4000 camera was used in this study. Photogrammetry also has the advantage of being operated by light sensors that can be carried onboard unmanned aerial vehicle (UAV) systems such platforms are useful for data acquisition over roofs and other non-accessible places. ![]() On the other hand, photogrammetry is more suitable for modeling those surfaces that can be decomposed in regular shapes, even though the development of dense matching techniques gave the opportunity to obtain results comparable to terrestrial laser scanners (TLS) in the reconstruction of free-form objects. Multiple scan stations can be integrated in a relatively easy way by means of consolidated registration techniques. Due to object size, shape, and occlusions, it is usually necessary to use multiple scans from different locations to cover every surface. Many studies about heritage documentation projects have been made by using laser scanning technique singly, or together with image based techniques. It is also increasingly used for digitization of cultural heritage. Terrestrial laser scanning should be preferred when the target is a complex structure that is difficult to model by means of geometric primitives. In reality, in many cases their integration in the optimal solution, being imaging and scanning techniques, are quite complementary. Plenty of literature has been published where different approaches are analyzed and compared. In the last decade, with the impressive development of digital photogrammetric techniques, scanning and 3-D imaging sensors, 3-D spatial data of architectural objects can be measured very quickly and precisely. It requires collecting and integrating high-density spatial data from the object surface. 3-D modeling has been practiced for many aims such as virtual reality, heritage building information model (HBIM) applications, documentation of historical structures, physical replication of artefacts, among others. Any kinds of geometric information about the object (volume, length, location, digital elevation model, cross-sections) can be retrieved from three-dimensional (3-D) digital models. In particular, recording their shape, dimensions, colors, and semantics may allow architects to restore their original forms and rebuild them when they would be destroyed. Therefore, their documentation is an important facet of this process. Cultural assets are extremely important structures to be transferred to next generations as the common heritage of the humanity.
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