Alexandrino Gonçalves

Illuminating the past: state of the art

Virtual reconstruction and representation of historical environments and objects have been of research interest for nearly two decades. Physically based and historically accurate illumination allows archaeologists and historians to authentically visualise a past environment to deduce new knowledge. This report reviews the current state of illuminating cultural heritage sites and objects using computer graphics for scientific, preservation and research purposes. We present the most noteworthy and up-to-date examples of reconstructions employing appropriate illumination models in object and image space, and in the visual perception domain. Finally, we also discuss the difficulties in rendering, documentation, validation and identify probable research challenges for the future. The report is aimed for researchers new to cultural heritage reconstruction who wish to learn about methods to illuminate the past.

Accurate modelling of Roman lamps in conimbriga using high dynamic range

The Human Visual System has a remarkable ability to acquire colour and contrast of all the things that surround us. This is particularly evident in extreme lighting conditions such as bright light or dark environments. However, it is simply not possible to represent such a range of lighting on a typical display today. This is about to change. The field of High Dynamic Range (HDR) imagery allows us to capture and display the full range of human vision. The use of technologies in the preservation and dissemination of cultural heritage can play an important role in the representation and interpretation of our past legacy. A major field of application is virtual reconstructions of ancient historical environments. In this domain, the way we see such (reconstructed) environments is particularly important in order to establish a correct interpretation of that historical setting. In this paper we present a case study of the reconstruction of a Roman site. We generate HDR images of mosaics and frescoes from one of the most impressive monuments in the ruins of Conimbriga, Portugal, an ancient city of the Roman Empire. We show that the HDR viewing paradigm is well suited for archaeological interpretation, since its high contrast and chromaticity can disclose and present us an enhanced viewing experience, closer to how the artefacts may have been perceived in the past. To achieve the requisite level of precision, in addition to a precise geometric 3D model, it is crucial to integrate in the virtual simulation authentic physical data of the light used in the period under consideration. Thereby in order to create a realistic physical based environment we use in our lighting simulations real data obtained from Roman luminaries of that time.

Incorporating legal rules on procedural house generation

The increasing demand for larger and more complex virtual models arising from different areas (e.g. design of virtual cities, video games and computer animated movies) creates the need for efficient computer algorithms able to generate them automatically. This paper presents a method for automatic generation of traversable houses, using architectural legal rules and an L-system to generate a list of interior rooms. The method is established with a framework specifically conceived to generate 2D floor plans and 3D models which allow the generation of multiple houses and interactive navigation.

High dynamic range—a gateway for predictive ancient lighting

In the last few years, the number of projects involving historical reconstruction has increased significantly. Recent technologies have proven a powerful tool for a better understanding of our cultural heritage through which to attain a glimpse of the environments in which our ancestors lived. However, to accomplish such a purpose, these reconstructions should be presented to us as they may really have been perceived by a local inhabitant, according to the illumination and materials used back then and, equally important, the characteristics of the human visual system. The human visual system has a remarkable ability to adjust itself to almost all everyday scenarios. This is particularly evident in extreme lighting conditions, such as bright light or dark environments. However, a major portion of the visible spectra captured by our visual system cannot be represented in most display devices. High dynamic range imagery is a field of research which is developing techniques to correct such inaccuracies. This new viewing paradigm is perfectly suited for archaeological interpretation, since its high contrast and chromaticity can present us with an enhanced viewing experience, closer to what an inhabitant of that era may have seen. In this article we present a case study of the reconstruction of a Roman site. We generate high dynamic range images of mosaics and frescoes from one of the most impressive monuments in the ruins of Conimbriga, Portugal, an ancient city of the Roman Empire. To achieve the requisite level of precision, in addition to having a precise geometric 3D model, it is crucial to integrate in the virtual simulation authentic physical data of the light used in the period under consideration. Therefore, in order to create a realistic physical-based environment, we use in our lighting simulations real data obtained from simulated Roman luminaries of that time.

Conimbriga as paradigm of cultural heritage (virtual) recriation

The preservation of the sites, monuments and other spaces, cultural heritage of the Humanity, has been one of the areas of greater use of computer graphics. This paper presents a methodology of expeditious and low-cost work aimed at virtual recreation of these historical spaces, which, through their availability on the web, allows its analysis and study by experts, as well as their access to the public, thus contributing to a better understanding of our history.

DinofelisAR demo augmented reality based on natural features

Augmented reality has seen a fast-growing gain of interest in the last few decades. Due to technological advances, smartphones are now devices that allow to experience augmented reality systems, anytime and anywhere. Although its emerging success among users, some problems AR have been reported inhibiting its full acceptance in our digital society. The aim of this paper is to present a study about techniques to implement augmented reality systems in the cultural heritage context, including a prototype to test the technology which, based on physical objects that belong to the landscape, present an effective and accurate augmented reality approach, overlaying 3D virtual models aligned over the real images, using a smartphones camera.

Mobile augmented reality in cultural heritage context: Current technologies

The use of augmented reality has a great potential applied to several areas, in particular, for cultural heritage context where it became possible to display, in loco, virtual elements which complement the users real scenario. Due to technological advances, differentiated ways of experience this technology has been explored, providing to common user, the access to this technology, until recently, quite limited, especially, in public locations. This article presents a work which includes implementation and evaluation of distinct applications of augmented reality — using smartphones — based on different techniques and tools. The evaluation intends to identify a solution to be implemented in a cultural heritage context, namely, the ruins of the Museu Monográfico de Conimbriga

Phenomena simulations for degradation prediction of cultural heritage buildings

Predicting buildings degradation and erosion by natural and artificial phenomena has been an unexplored area. In this article is presented natural and artificial phenomena simulations applied to a tridimensional model, using physics mechanics, created algorithms and using materials, which aims to be used to predict buildings level of destruction in the next years.