| | | | | | | |

Carpiniana: A Virtual Representation of the Byzantine Crypt of Santa Cristina

2002 - Carpignano Salentino, Italy

In 2002, the SIBA Coordination at the University of Lecce in Italy invited NRC to collaborate in a project, using the latest in multimedia technology, to document the Crypt of Santa Cristina. The Crypt, located in Carpignano, Apulia was excavated (rupestrian site) around the 9^th century c.e. It measures about 16.5 m x 10 m x 2.5 m and has a number of well-preserved frescoes on the walls. During the project we demonstrated a technique that combines high-resolution textures recorded using a digital camera with the shape data recorded from a 3D Laser Scanner to create a complete photo-realistic 3D model of the Byzantine Crypt.

A photogrammetric technique was used for the outside (i.e. main and secondary entrances located above the Crypt) while a commercial laser range scanner was used to provide plain (shape only) clouds of 3D points for the interior of the Crypt itself (located underground). Texture was acquired with a high-resolution 6 mega-pixel digital camera. The 2D digital photographs were not only used to produce 3D textured models but also to perform geometric measurements. Proper camera calibration and bundle adjustment algorithms combine in digital photogrammetry to give accurate feature coordinates and reliable pose estimations [Beraldin VSMM 2002 and Beraldin SPIE 2003].

Figure 1a: 3D models of the Crypt of Santa Cristina in Carpignano, Italy

Figure 1b: 3D models of the Crypt of Santa Cristina in Carpignano, Italy

Figure 1: 3D models of the Crypt of Santa Cristina in Carpignano, Italy
Accurate photo-realistic 3D models of heritage sites offer important new ways to study, to promote and to protect sites. The portion of the Crypt shown with synthetic shading in (a) illustrates irregular shape of the walls. Capturing the three-dimensionality such as this is an important aspect. (b) Illustrates same portion after texture mapping showing a higher level of realism. (For more information, see Reference VSMM2002 & SPIE2003.)
Click on the image for a larger view

An accurate 3D site model contains a wealth of information that can be analyzed and enhanced. Features, such as tool marks or surface texture that are small or only visible from a distance can be interactively examined, thus, allowing the study of fine details. To compliment or help plan physical restoration of the site, “virtual restoration” can be applied directly to the digital copy. For example, faded images can be enhanced (Figure 2) and architectural elements that have been added over the years can be removed. To do, so however, it is important to create a geometrically correct, visually realistic, and highly detailed 3D model.

Figure 2: Example of a simple virtual restoration of an inscription, (a) current state of some of the inscription, (b) enhanced version with some modifications to the texture image that is re-mapped by simply reloading the 3D model in the viewer.
Click on the image for a larger view

The work on the Byzantine Crypt "Carpiniana" won the e-science award in Italy, in July 2005. The juror’s comments noted: "This product is an outstanding application of interactive computer graphics designed in order to perfectly reproduce shape, size and colours of a Byzantine Crypt. Both jurors with art historian background and IVR background highly appreciated the product."