3D visual information and GIS technologies for paintings’ documentation in the M Sepulchre in the Vatican Necropolis

Introduction

The Vatican Necropolis 

The M Sepulchre

Microtopographic survey

3D Arm

Thermal Infrared Analysis

GIS

VRML

Gradoc index

The main goal of our project was the virtual detailed 3D reconstruction of micro-models of paintings documentation by digital techniques and through different information layers, in order to have a final "cognitive" representation. In the case of a monument, such   as a tomb, the best cognitive micro-representation is increasing the  level of knowledge and of interpretation, practically de-constructing, in a first phase the pictorial and architectonic information, finally,  recombining every component of the structure into a unique, whole virtual model. The process of de-construction and re-construction is a cognitive dynamic process of knowledge that we think is fundamental for a new approach to the digital graphic representation: we disassemble and then reassemble information. Thus a model becomes an articulated set of multilayered information,  where the whole increased model is more significant than each single component. In this context, 3D GIS (Geographic Information System) and virtual reality technologies have been fundamental in obtaining good results. In fact, even though GIS software is typically used in territorial studies and analyses, it can give very interesting results also in other non-traditional contexts. Furthermore we have to consider GIS as an open planning platform, where the scientific user chooses the directions of research, combining the several layers of documentation.

 Now, click on the walls for displaying the movies

All the phases of work have been carried out exchanging all the data on line (by Internet tools) and creating a network of persons with different roles and functions: topographic survey and acquisition (A. Bizzarro, S. Tilia), data processing (S. Tilia), rectification and topological referencing of the images (A. Tilia), GIS implementation and 3D processing (M. Forte), VRML reconstructions and virtual reality applications (A. Tilia, S. Tilia, M. Forte). In order to process the digital data the following software have been used:

1. Er Mapper 6.1 (3D visualisation and draping, infrared spectral analysis);
2. Arcview 3.1 (GIS data-entry and overlay);
3. VRML Cosmo Player (3D visualisation of the model reconstructed).

In our case the most important phase of the work was the superimposition of the data, that is the representation of the data in a unique referenced co-ordinate system, through the exact use of a GIS implementation.

The working project

• Data entry of vector (drawings) and raster (images) files.

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  Topological referencing of raster (photomosaics and graphics) and vector (decorations, drawings) layers in Arcview

• 3D interpolation data by CAD and GIS software (Arcview 3D Analyst) for the creation of 3D surfaces (interpolation by GRID and by TIN.

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• 3D Superimposition of all the geometric and graphic layers.

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• 3D Texture mapping of the graphic documentation over the model and draping of all the referenced data over the microDEM of the walls and of the vault.

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• Real time visualisation of the virtual models (in our case 4 models for the documentation of the tomb) using Er Mapper and the 3D Analyst module of Arcview.

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• Merging of all types of data systems in order to analyse and to compare the different information layers (raster and vector, such as images, contour lines, polylines, graphic edges, interpretations and so on).

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• Z exaggeration of the interpolated models in order to stress the surfaces for testing the state of conservation of the mural paintings, and the relationships between mosaics, graphic decorations, architectonic elements, lack of materials, etc.

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• Model reconstruction in VRML (Virtual Reality Modelling Language, see below) in order to visualise and to interact the data on line in Internet or off line on any PC.

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