Recovering Old Stereoscopic Negatives and Producing Digital 3d Models of Former Appearances of Historic Buildings

Abstract

ABSTRACT:Three-dimensional models with photographic textures have become a usual product for the study and dissemination of elements of heritage. The interest for cultural heritage also includes evolution along time; therefore, apart from the 3D models of the current state, it is interesting to be able to generate models representing how they were in the past. To that end, it is necessary to resort to archive information corresponding to the moments that we want to visualize.This text analyses the possibilities of generating 3D models of surfaces with photographic textures from old collections of analog negatives coming from works of terrestrial stereoscopic photogrammetry of historic buildings. The case studies presented refer to the geometric documentation of a small hermitage (done in 1996) and two sections of a wall (year 2000).The procedure starts with the digitization of the film negatives and the processing of the images generated, after which a combination of different methods for 3D reconstruction and texture wrapping are applied: techniques working simultaneously with several images (such as the algorithms of Structure from Motion -SfM) and single image techniques (such as the reconstruction based on vanishing points). Then, the features of the obtained models are described according to the geometric accuracy, completeness and aesthetic quality. In this way, it is possible to establish the real applicability of the models in order to be useful for the aforementioned historical studies and dissemination purposes.The text also wants to draw attention to the importance of preserving the documentary heritage available in the collections of negatives in archival custody and to the increasing difficulty of using them due to: (1) problems of access and physical conservation, (2) obsolescence of the equipment for scanning and stereoplotting and (3) the fact that the software for processing digitized photographs is discontinued.

Interactive virtual representation of the disappeared convent of El Carmen (Logroño) generated from a paper craft model

“…In the case of the aforesaid paper model, we resorted to two techniques that are suitable for virtual modelling from scarce sources. Especially, the 3D geometry was reconstructed from perspective analysis using individual photographs, (in particular, using the software SketchUp®) and, whilst additionally, textures were extracted monoscopically by means of individual orientation and rectification of each façade (Rodríguez & Valle, 2017). The workflow is summarized in Figure 2.…”

Auscultación y prevención de mecanismos secundarios de colapso en puentes históricos en ruinas mediante el uso de valores métricos obtenidos de fotografías de archivo y el análisis geométrico del intradós

“…For the case of the Mantible bridge the situation was still more unfavourable since we were looking for tracking a dynamic and, thus, the information for different years had to be considered separately. Consequently, we resorted to the dimensional reconstruction through vanishing points (43), a technique that allows working with individual images and that has proven to be useful for 3D reconstruction of heritage buildings from archival photographs (44).…”

An automatic workflow for orientation of historical images with large radiometric and geometric differences

“…In architectural photogrammetry, recent research shows that Agisoft PhotoScan/Metashape is often capable of reconstructing a building, or part of a building, using historical images. Limitations to be considered are the automatic selection of appropriate images, retrieving the inner orientation of the camera (Grussenmeyer and Al Khalil, 2017) and the final 3D model quality (Maiwald et al, 2017; Rodríguez Miranda and Valle Melón, 2017; Beltrami et al, 2019).…”