3D VIRTUALIZATION BY CLOSE RANGE PHOTOGRAMMETRY INDOOR GOTHIC CHURCH APSES. THE CASE STUDY OF CHURCH OF SAN FRANCISCO IN BETANZOS (LA CORUÑA, SPAIN)

Abstract. Virtualization using low cost photogrammetric techniques, is often replaced by Terrestial Laser Scanning inside churches. Especially in the case of Gothic churches where light penetrates the interior of the building difficulting shooting in proper condition to perform their restitution. The need to use Terrestial Laser Scaning for indoor virtualization is a significant increase in the final surveying cost. In these cases, the Terrestial Laser Scanning is used to generate dense point clouds that can produce high resolution models. However, many Terrestial Laser Scanners are not able to provide color images or can not reach the quality of images which can be obtained through a semiprofessional camera. So, digital photogrammetry is often used to make these models high resolution textures that Terrestial Laser Scanner based methodology is not capable of providing. This article aims to solved the problem posed by virtualizating Gothic churches indoors. Making that task more affordable exclusively by low cost photogrammetric techniques. The proposed methodology allows obtaining photographs in such a good conditions for virtualizing the target by point cloud. In order to verify the usefulness of the method, It has been decided to apply it to Gothic apse of the church of San Francisco in Betanzos (La Coruña). The equipment used is inexpensive and easy to carry: DSLR camera with 18-135 mm lens, tripod, lights and total station.