The research project KosmoTech_1200, led by the University of Santiago de Compostela in collaboration with CISPAC and the Fundación Catedral de Santiago, has unveiled the digital restoration of the portrait of Master Mateo, located on the base of the central pillar of the Pórtico da Gloria.
Directed by CISPAC researcher Francisco Prado-Vilar, the project combines advanced digital technologies and historical analysis to virtually reconstruct one of the most iconic images of Santiago Cathedral, popularly known as “the saint of the head bumps.” The intervention has made it possible to restore missing parts of the sculpture and propose a reconstruction of its original polychromy, recovering the visual intensity and presence it would have had in its medieval context.
The digital restoration was carried out by Alexandre González Rivas, who was responsible for the visualization and reconstruction process, using a combination of multiple specialized tools. The work integrated 3D modeling, photogrammetry, and chromatic reconstruction techniques to virtually recover the original appearance of the sculpture based on the research developed by Francisco Prado-Vilar. In an initial phase, a high-resolution photogrammetric model was used to generate a densely optimized mesh through retopology and topological cleanup processes, onto which the digital reintegration of missing parts was carried out using 3D sculpting. This intervention made it possible to correct visible deterioration, especially in the lower part of the figure, relying both on historical photographic evidence and on criteria of geometric continuity and structural coherence.
Additionally, normal maps and displacement maps were used to preserve the surface detail of the original scan, integrating them with the new contributions. The process was aimed at restoring the rhythms of the drapery and reestablishing coherence in the system of folds that structures the fall of the tunic and cloak around the figure, always respecting the material and constructive logic of the sculpture. In a final phase, a hypothetical reconstruction of the polychromy was carried out, based on the analysis of pigments and decorative motifs documented in the original polychromy of the Pórtico, as well as on parallels from the illumination of contemporary manuscripts. This chromatic reconstruction was developed using PBR textures and maps of color, specularity, and roughness, in order to simulate the material behavior of the different pictorial layers under varying lighting conditions.
Beyond its technical dimension, the project includes an iconographic study that reinterprets the meaning of this figure. The gesture of Master Mateo, with his hand placed over his chest, is understood as an expression of the medieval concept of sapiens architectus: the wise architect who conceives the work internally —in the heart— before bringing it into material form.
The restoration also encompasses the sculptural ensemble of the base, where a second figure is proposed to be identified as Judas, reinforcing the symbolic and political dimension of the Pórtico da Gloria’s program. Coinciding with the anniversary of April 1, 1188 —the date when the lintels of the Pórtico were installed— the project brings together historical research and digital technologies to offer a new approach to one of the key works of European medieval art.
You can view the digitally restored portrait of Master Mateo in the following video:
Below you can download the full iconographic research dossier of the project, which expands on and thoroughly documents the interpretative hypotheses presented.