Virtual Restoration of Cultural Heritage Through Real-Time 3D Models Projection

The color techniques used in sculpting items of cultural heritage change over the years. The demand to restore a unique version of history to the detriment of the rest of time motivates us to research to attain full restoration of the polychromes (painting on stone). This problem, along with currently prevailing non-invasive trends in restoration, lead us to use Augmented Reality to achieve virtual restoration of the portico of the Saint Mary’s Cathedral in Vitoria (Spain). By projecting the rendered image of the 3D model of the polychromed sculpture in real time over the original sculpture, we can make the sculpture appear to the eyes of the observer as if it had the same polychromes/paint as it did in the past. In this fashion, we achieve the desired restoration effect without touching the stone while being able to show the polychromes of each and every one of the eras that the portico has stored up. To carry out this project, we need to conduct a study prior to the use of projectors on the portico, and, in effect, the offered solution to use the Augmented Reality is valid to obtain the restoration objective. Due to the fact that the portico is not able to be worked on, we cannot do a complete, on site study. We solve this problem by conducting a 3D simulation of the entire portico. With the virtual portico, we can validate the display of the polychromes and the layout and lighting over the projectors. To validate the restoration using projectors, we test the projection on the central element of the portico: the chest of the White Virgin. We project the model that was scanned in 3D with polychromes discovered by restorers on the chest, thus validating the entire system when it comes to the quality of the polychromes, technically and economically speaking.