### Retrospective Photogrammetry: Examples  
Retrospective photogrammetry methods are used for the processing of archival terrestrial and aerial images for the 3D reconstruction of entities that no longer exist. In the literature, one can find many examples of the practical use of retrospective photogrammetry. The forerunner of the preservation of cultural heritage by using photogrammetric techniques was [PERSON] (1834-1921). [PERSON] was aware of upcoming risks to cultural objects, so his idea was to use photographic images for the documentation of buildings [9]. Between 1885 and 1920, [PERSON] recorded about 2600 objects in about 20,000 photogrammetric images on glass plates. The Berlin French Cathedral of 1882 was the subject of one of [PERSON]'s experimental photographs (40 \(\times\) 40 cm). About 100 years later, between 1977 and 1982, the image was used for the reconstruction of the church, which was severely damaged during World War II. [PERSON]'s basic method was to combine a photographic camera and a measuring instrument into one single system [10]. One of the earliest attempts at photogrammetric reconstruction involved the use of archive photographs for the restoration of Castle Howard in Yorkshire, England, which was damaged by fire in 1940 [11]. Pre-war photographs were also used for 3D modeling in the Lusatian Borough, Biskupin. Pre-war photographs were taken from different heights: from a captive balloon (maximum height up to 150 m), from a blimp (at a height of 50-110 m), and from an airplane (at heights of 200 m, 300 m, and up to 3 km). The Structure from Motion technique implemented in commercial software (Agisoft Metashape 2.1.4.) was used to generate 3D models [12]. Another example is the story of the famous Bamiyan states, which were demolished by Taliban forces in March 2001. ETH Zurich volunteered to produce a computer reconstruction that could serve as the basis for a physical reconstruction. The work was based on three different types of images, which were used in parallel: (1) a set of images acquired from the Internet (\"Internet images\"); (2) a set of tourist images acquired in the Bamiyanvalley between 1965 and 1969 (\"Tourist images\"); and (3) three metric images acquired in 1970 by Professor [PERSON] of the Technical University of Graz. Ultimately, metric images dating from 1970 proved to be the best for the 3D reconstruction of the [PERSON] statues. From these, a wireframe model was developed, and the object was physically reconstructed using 3D printing technology [13]. The use of 12 archival negatives for 3D modeling of bird dinosaur tracks is another example. In this case, [PERSON]'s Paluxy River dinosaur \"chase sequence\" had not existed in a complete form since it was excavated in 1940, more than 70 years ago. After excavation, some parts were distributed to several institutions and others were completely lost. The polygonal surface was generated from a dense point cloud using the Screened Poisson Surface Reconstruction algorithm. The Paluxy project remains a landmark work in the use of non-photogrammetric archival imagery for 3D printing [14]. Another example of the use of archival photographs relates to urban planning. The aim of the Lx Conventos project is to investigate the influence of convents on the dynamics of urban change in nineteenth-century Lisbon. The Lx Conventos project aims to show that the convents of the time played a decisive role in the urban development of Lisbon. The project is based on a large multimedia data set, including history and contemporaneity, with cartographic maps and georeferenced images, videos, and 3D models provided by the project partners, the Municipality of Lisbon, and the Portuguese National Archive, Torre do Tombo [15]. The Viskalia project attempts to recreate extinct architecture, aiming to produce digital 3D reconstructions of up to fifteen models of selected no longer existing or altered rural architectural buildings.