Supporting an Efficient 3D Reconstruction of Urban Cultural Heritage for Serious Games

Ability to support contextualized (situated) learning is one of the most prominent features of serious games (SGs). Thus, the context settings of a SG (e.g., 3D reconstructions, maps, sounds, etc.) should be carefully designed in order to provide realism and credibility. This is particularly true for SGs dedicated to the cultural heritage, since objects that are usually seen in a museum or in archeological park are decontextualized, while a SG could provide a compelling adventure setting these objects in their actual context, thus showing their actual meaning and functionality (and allowing players to work with them). We believe that this is an important added-value for education.

A common context for cultural heritage is a urban area, which is an area where we at the ELIOS Lab are working since the Strada Nuova 3D stereo movie and the Travel in Europe (TiE) project.

A 3D reconstruction of an urban area for SGs requires a careful trade-off among the 3D models’ realism, weight and development time. This has led us to the definition of an algorithm – the Architectonic Style Area (ASA) algorithm – for procedural generation of buildings in an urban area, based on the concept of ‘‘architectonic likelihood’’, that intends to give players the sense of being in a particular city or even specific area of a city. This has a cognitive foundation in the fact that, after a visit, a tourist typically does not remember every single palace of a city, but remembers – beside the most important monuments and buildings (points of interest) – its general features and its architectonic styles. The algorithm extrudes 2D maps and composes facades by statistically assembling sample images of architectonic components from the target city. For describing and classifying architectonics components, we have defined an ontology based on the classic principles of architecture. The algorithm relies on rules that encode the semantics of the ontology.

Given their obvious specificities, Points of Interest (PoIs) are not suited to be represented through the statistical algorithm. Thus, they need separate modeling (typically by hand).

Strasbourg1   Strasbourg2

Snapshots from an ASA area in Strasbourg

The algorithm has been implemented in Travel in Europe, a SG project for the promotion of the cultural heritage. Results show that the approach allows keeping the realism of every single building at good detail and of the overall scene, while dropping a huge work of image collection and processing for the textures.

Genoa_carrugi1   Genoa_carrugi2

Screenshots of an ASA reconstruction in the Genoa city center featuring the narrow streets (“Carruggi”) with typical elements like portals, windows and plasters

Genoa_Carrugi_Aerial

Aerial view of an ASA in the Genoa model

You can find more information here:

Bellotti F., Berta R., De Gloria A. and Cardona S., “An architectural approach to efficient 3D urban modeling”, Computers & Graphics, Vol. 35, Issue 5, October 2011, Pages 1001-1012

Bibliography:

Mueller P, Wonka P, Haegler S, Ulmer A, Van Gool L. Procedural modeling of buildings. ACM Transactions on Graphics 2006;25(3):614–23.

Smelik RM, Tutenel T, de Kraker KJ, Bidarra R. Interactive creation of virtual worlds using procedural sketching. In: Proceedings of eurographics 2010—short papers, Norrkoeping, Sweden; 3–7 May 2010.

Mueller P, Zeng G, Wonka P, Van Gool L. Image-based procedural modeling of facades. ACM Transactions on Graphics (TOG) July 2007;26(3).

Xiao J, Fang T, Zhao P, Lhuillier M, Quan L. Image-based street-side city modeling. ACM Transactions on Graphics December 2009;28(5).

Bellotti F., Berta R., De Gloria A., Primavera L., “Supporting authors in the development of Task-Based Learning in Serious Virtual Worlds”, British Journal of Education and Technologies (BJET), Vol. 41, No. 1, January 2010 , pp. 86-107

Bellotti F., Berta R., De Gloria A., Primavera L., “Adaptive Experience Engine for Serious Games”, IEEE Transactions on Computational Intelligence and AI in Games, Vol 1, No. 4, 2009, pag. 264-280.

Bellotti F., Berta R., De Gloria A. and Cardona S., “An architectural approach to efficient 3D urban modeling”, Computers & Graphics, Vol. 35, Issue 5, October 2011, Pages 1001-1012

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