INTRODUCTION isprsarchives XL 5 W4 375 2015

3D TRACKING BASED AUGMENTED REALITY FOR CULTURAL HERITAGE DATA MANAGEMENT C. Battini a , G. Landi b a DICCA, Department of Civil, Chemical and Environmental Engineering, 16145 Genova, Via Montallegro 1, Italy – carlo.battiniunige.it b ETT s.p.a., 16154 Genova Sestri Ponente, via Sestri 37, Italy - giovanni.landiettsolutions.com Commission V, WG V4 KEY WORDS: Augmented reality, Laser scanner, Tracking 3D, Reverse modelling, Survey ABSTRACT: The development of contactless documentation techniques is allowing researchers to collect high volumes of three-dimensional data in a short time but with high levels of accuracy. The digitalisation of cultural heritage opens up the possibility of using image processing and analysis, and computer graphics techniques, to preserve this heritage for future generations; augmenting it with additional information or with new possibilities for its enjoyment and use. The collection of precise datasets about cultural heritage status is crucial for its interpretation, its conservation and during the restoration processes. The application of digital-imaging solutions for various feature extraction, image data-analysis techniques, and three-dimensional reconstruction of ancient artworks, allows the creation of multidimensional models that can incorporate information coming from heterogeneous data sets, research results and historical sources. Real objects can be scanned and reconstructed virtually, with high levels of data accuracy and resolution. Real-time visualisation software and hardware is rapidly evolving and complex three-dimensional models can be interactively visualised and explored on applications developed for mobile devices. This paper will show how a 3D reconstruction of an object, with multiple layers of information, can be stored and visualised through a mobile application that will allow interaction with a physical object for its study and analysis, using 3D Tracking based Augmented Reality techniques.

1. INTRODUCTION

Three-dimensional survey techniques are increasingly used today for cultural heritage studies. The collected data may be the basis for morphological and preservation analysis of objects. These survey techniques generate datasets, which are the fundamental basis on which new and general information is overlaid. This process is in a new spatial location and creates relationships between various types of results thereby giving new interpretation tools. There are numerous 3D collection technologies available today, some of which use laser. These instruments permit the capture of complex geometries with a degree of resolution that varies depending on the technique used. The results must be defined in the design phase of the survey and must be to the scale used for visualization. Cultural Heritage documentation often includes results rendered in scale 1:50 and, in some cases, 1:20. These scale factors are able to decipher the peculiarities of the piece very accurately, showing not only the form but also the colouring of the materials used. This data is essential for successful restoration planning and design. By restricting the range of technologies available to scale 1:20, the use of phase-shifting approaches, with a measurement tolerance of 2-3 mm, is a good way recording morphological composition; also for statues, where this type of technology involves information discretisation and highlights the reflectivity of the material exposed to a beam of light. Dedicated applications process this information and extract dimensional and colouring information. It is unfortunate that the data obtained is only available to those with special training in computer graphics, usually based in distant laboratories. Other data that need to be collected during the restoration and conservation phases concern conservative and material peculiarities. This information is useful when choosing the most suitable restoration technique and materials. The complexity and the amount of collected data often leads to the creation of complex and not easily transferable maps and reports. The project described in this article aims at making all this information available on site, simply and immediately. This system permits greater interaction with objects and delivers simple information organisation tools that also store data for easy integration with other software. In this way, the data will always be available and will facilitate comprehension of the decay conditions. The aim of the project is also to give basic information to unskilled users, such as tourists. It will therefore be possible to classify the article and show precise information on the iconographic and material composition, thereby encouraging greater understanding of the design idea behind the piece of art.

2. CASE STUDY