Abstract
Reverse engineering applied to architectural restoration for the reconstruction of structural surfaces depends on metric precision. Sometimes there are elements on these surfaces whose value is even higher than the building itself. This is the case for many churches whose ceilings have pictorial works of art. Reconstruction requires the existence of some identifiable remainder and/or a surface geometry that enables mathematical development. In our case, the vault has an irregular hemispherical geometry (without possible mathematical development), and there are no significant remains of the painting (which was destroyed by a fire). Through the 3D modelling of the irregular vault and two historic frames with a camera of unknown geometry, an inverse methodology is designed to project the original painting without metric deformations. For this, a new methodology to locate the camera positions is developed. After, a 3D virtual mathematical model of the complete image on the vault is calculated, and from it, partial 3D virtual images are automatically calculated depending on the variable unknown positions of the video cannons (distributed along the upper corridor of the apse) that will project them (visually forming a perfect complete 3D image).
Highlights
Classical photogrammetric techniques have been used for reverse engineering in buildings for decades [1], and currently, due to UAVs, their applications are even more common [2,3]
Due to the laser scanner, the application of both techniques together allows for non-invasive reverse engineering processes where no contact with the element is necessary [18,19,20,21,22], which is especially relevant in heritage studies [23]
This study shows the restoration by video projection of the paintings that were destroyed by a fire on the vault of the church of Santos Juanes in Valencia
Summary
Classical photogrammetric techniques have been used for reverse engineering in buildings for decades [1], and currently, due to UAVs, their applications are even more common [2,3]. The solution will be to perform the reconstruction directly on the element by projecting images on its surface (with video cannons) in the original position and without metric deformation. This implies being able to define the geometry with the greatest accuracy so that we can project partial images on the real surface by mathematically controlling the deformations of the projection and the scale of each of them. It will be necessary to first calculate a complete 3D virtual image of paintings on the mathematical modelling of this irregular surface (from the original frames) and calculate 3D partial virtual images (which will be projected by each video cannon). The scan was performed from 4 positions, obtaining a complete point cloud formed by 80,000,000 points (Figure 1)
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