Enhancing the Cultural Heritage between Visual Technologies and Virtual Restoration: Case Studies to Models for Visual Communication

Enhancing the Cultural Heritage between Visual Technologies and Virtual Restoration: Case Studies to Models for Visual Communication

Elena Ippoliti (Sapienza University of Rome, Italy) and Michele Calvano (Sapienza University of Rome, Italy)
DOI: 10.4018/978-1-5225-0680-5.ch013
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Abstract

Enhancement of the cultural heritage is not simply a matter of preserving material objects but comes full circle only when the heritage can be enjoyed and used by the community. This is the rationale behind this paper: the application to exploring projects for the Casa del Fascio (Fascist Party Office) and the building complex of Foro Mussolini in Littoria (now Latina), by the architect Oriolo Frezzotti. Starting with consistent iconographic documentation integrated with bibliographic research and comparison with similar cases, the historical process was retraced and interpreted, reconstructed three-dimensional hypotheses of the figural unity were formulated, and interactive application was created. The application refers to the area of “virtual restoration”, the only possibility for non-material histories and works, a field in which visual technologies can prolong the critical “eye” to which recomposition of the figural combination is entrusted.
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Introduction

The objective of the chapter is to present two particular “representation” experiments where visual technologies aimed at simulating the space are interpreted as active devices to construct accessible, participatory, and involving communication of Cultural Heritage. The “3D digital scene” lies at the heart of the applications. It is the “participatory” place par excellence to construct information and access cultural content. The “3D digital scene” and more generally the “visual models” activate means of approaching the Cultural Heritage. They centre on emotional involvement, favouring involvement and participation through the experience.

A common denominator of the different applications is therefore the 3D model. It is, however, “dilated” by integration and overlays with different environments. In particular, the applications offer exploration of digital reconstructions of the case studies, testing the following:

  • The static spherical panorama: a digital model from which panoramic representations and 360° navigable Virtual Tours are derived, but only from fixed points of view. It is therefore useable in a discrete, discontinuous way.

  • The dynamic interactive perspective for real-time navigation of the digital model (Migliari, 2008). This allows for greater interaction with the reconstructed space, which can be explored in a fluid, continuous way.

  • The presentation follows and describes the phases of experimentation, for this purpose is organized into four parts.

In the first part, the case studies for which the applications were developed are described in detail, pausing on the historical/critical analysis on which the digital reconstruction of the 3D spaces is based. In fact, the reconstruction hypotheses of the figural unity of the projects were formulated starting with consistent iconographic documentation integrated with specific bibliographic research and comparison with similar cases.

The second part presents the goals of the enhancement and its possible users. The experience proposed is specified along with its levels of use and interaction.

The third and fourth parts describe in detail the main procedural and technical questions that characterized the experimentation. The presentation is organized relative to the objectives of the different phases, with some specific methodological and technical analysis situated in the scientific context of reference.

In particular, the third part describes the procedures used to create the 3D models for applications, that is:

  • The metric/geometric construction of the 3D models based on rigorous, point-like information regarding the geometry, form, and measurements,

  • The perceptual rendering of the models, from the choice of surface materials to treatment of the 3D models, for a perceptual result that agrees with the historical/critical interpretation,

  • Finally, the fourth part describe the main procedural and technical questions that characterized the creation of the applications themselves, that is:

    • o

      The procedure to create the Virtual Tour, with an analysis of the spherical panoramas and virtual tours situated in the context of cartographic and photogrammetry representations

    • o

      The procedure to realize the Real-Time Navigable Model, with various analyses related to questions of discretization and the perceptual rendering of the model in relation to its real-time exploration.

Key Terms in this Chapter

3D Modelling or 3D Digital Modelling: 3D modelling or 3D digital modelling indicates the process aimed at reconstructing the three-dimensional form of an object in virtual space generated in a computing environment. The reconstructed 3D form is called 3D digital model or 3D model; the software programs used to create it is called 3D modeller or 3D software.

Casa del Fascio: In 1921, Benito Mussolini founded the National Fascist Party, thus transforming the movement of the Fasci di Combattimento (Italian Fasci of Combat). The term fascio therefore indicated the party itself, the local party organizations, and the offices, called Case del Fascio, distributed in the various Italian cities. The administrative and celebratory functions directly connected to the party were carried out in the Case del Fascio. In the main Italian cities they also performed different services for the people, for example, physical and cultural education, leisure and relaxation. The Casa del Fascio was also called Casa Littoria or even Palazzo Littorio. In fact, as one of its symbols, Fascism used the fascio littorio (a weapon consisting of a bundle of rods carried in Ancient Rome by the lictors), so littorio became a synonym of Fascism.

Virtual Tour: The virtual tour is a type of virtual-reality application in which the visitor can observe the reconstructed 3D space in 360°; however, exploration of the space is limited to predefined points. A virtual tour is created by using special software to develop static spherical panoramas that in turn are obtained from 360° photography from a single station. The static spherical panoramas can also be obtained from 3D models.

Texture Mapping: This term indicates the process regarding the correct positioning of 2D images (bitmap) on the surfaces of a numerical or polygonal model. More precisely, it is the process through which each mesh of the polygonal model is assigned a particular texture described by a texel (texture pixel) matrix. It is realized by creating a projection correspondence between the mesh vertices—described in 3D orthogonal digital (xyz) space by XYZ coordinates—and the image points—intrinsically oriented according to the 2D (uv) system of reference with UV coordinates. There are different means of realizing these associations, which are distinguished according to the geometric characteristics of the models. Texture mapping is used when a perceptually accurate 3D model is necessary.

Real-Time Navigation: Real-time navigation is a type of virtual-reality application in which the visitor can move freely without obstacles other than those that a real space would have, and the navigation through the 3D space is fluid because interaction with the virtual environment is in real time, i.e., perceived without delays between input and system response. So that a 3D model can function in these applications, it should be particularly precise in rendering details and contextually “light”, that is, with a restricted number of polygons so that the weight of the geometry does not negatively influence the navigational fluidity. Dedicated software systems are used for these applications. Until a few years ago, these were only used in the videogame sector, but they have become more widely used due to their simplified interfaces.

Numerical or Polygonal Representation: Numerical or polygonal representation is the “discrete” description of the shape of an object by means of a finite number of plane faces (triangles or polygons) called a mesh. It is created in the computing environment with graphical software called numerical or polygonal numerical modellers. With this type of representation, the shape of the object is therefore approximated by a polygonal mesh described via vertices, corners, and faces. The numerical representation is necessary in rendering operations and is therefore used when a perceptually accurate description of the object is necessary.

Interactivity and Immersion in Virtual Reality: “Interactivity” when speaking about virtual reality refers to the particular relationships established between the digital model and its users. It indicates the possibility that the user participates in the process of information transfer mediated by the computer. A medium is therefore interactive if it allows the user to influence the communicational content or form. There are different levels of interaction: the lowest allows the user simply to choose information; the middle allows the user to create or insert content; the highest makes the virtual environment respond appropriately to the user’s input. “Immersion” in virtual reality should be correctly understood only in immersive simulations where the user interacts with the environment via all five senses. However, the term usually refers to spatial simulations that are usable only through sight, that is, via screens in which the user has the impression of being able to move freely.

Texture Baking: Texture Baking is any process aimed at generating libraries of texture maps that describe the different qualities of the surface of a 3D model in a scene (materials, texture, colour, lighting, shadows, reflections, etc.). These are memorized and associated with the information describing the 3D model. This procedure—also called Rendering to Texture—pre-calculates the effects of rendering to generate bitmap images that are expressed in the 2D (uv) system of reference and coherently oriented with the mesh vertices. With this technique, it is not necessary to make involved rendering calculations for each movement of the model because the realistic result is ensured by associating the maps to the surfaces of the object in (uv) space. This procedure is therefore particularly indicated for applications requiring 3D spatial navigation in real time, i.e., perceived without delays between input and system response.

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