3D Ancient Mosaics Sebastiano Battiato Image Processing Lab Dipartimento di Matematica ed Informatica Università degli Studi di Catania battiato@dmi.unict.it Giovanni Puglisi Image Processing Lab Dipartimento di Matematica ed Informatica Università degli Studi di Catania puglisi@dmi.unict.it ABSTRACT Digital 3D mosaics generation is a current trend of NPR (Non Photorealistic Rendering) field; in this demo we present an interactive system realized in JAVA where the user can simulate ancient mosaic in a 3D environment starting for any input image. Different simulation engines able to render the so-called ”Opus Musivum” and ”Opus Vermiculatum” are employed. Different parameters can be dynamically ad- justed to obtain very impressive results. Categories and Subject Descriptors I.3.0 [Computer Graphics]: General; J.5 [Art and Hu- manities] General Terms Algorithms, Experimentation. Keywords Digital Mosaic, NPR 1. INTRODUCTION Artificial (and digital) mosaics are illustrations composed by a collection of small pictures called tiles. The tiles tes- sellate a source image with the purpose of reproducing the original visual information rendered into a new mosaic-like appearance. The same source image may be translated into many strikingly different mosaics. Factors like tile dataset, constraints on positioning, deformations and rotations of the tiles are indeed very influential upon the aesthetic final re- sults. In this work we are mainly interested in digital mosaic resembling the visual style of an ancient looking man-made mosaic; in this context there is a challenging problem be- cause it has to take into account the polygonal shape and the dimensions of the tiles, the need to pack the tiles without too evident holes and, not last, the strong visual influence that tile orientation has on the overall perception of the mo- saic. In particular orientation cannot be arbitrary but it is Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. MM’10, October 25–29, 2010, Firenze, Italy. Copyright 2010 ACM 978-1-60558-933-6/10/10 ...$10.00. constrained to follow the gestalt choices made by the author of the source image. See [2, 5] for a complete and updated survey of the overall related techniques. In this demo we will present the generation of 3D ancient mosaic starting from any digital image. In particular we have chosen to realize this experiment, starting from the two recent solutions presented in [1, 3, 4, 7] that reproduces with different heuristics the well known techniques ”Opus Musivum”and ”Opus Vermiculatum”. The 3D rendering, as better specified below allows to reach impressive results as demonstrated by the attached video. 2. ANCIENT MOSAIC GENERATION The problem of digital mosaic creation can be stated within a mathematical framework. In particular starting from a raster source image the corresponding digital mosaic is de- rived by making use of a mathematical optimization problem as follows: Given a rectangular region I 2 in the plane R 2 , a tile dataset and a set of constraints, find N sites Pi (xi ; yi ) in I 2 and place N tiles, one at each Pi , such that all tiles are dis- joint, the area they cover is maximized and the constraints are verified as much as possible. Ancient mosaics are artworks usually constituted by ce- menting together small colored tiles. Appropriate use of shape, orientation, and size may allow to convey much more information than casual distribution of N graphic primitives (like pixels, dots, etc.). For example, ancient mosaicists avoided lining up their tiles in rectangular grids, because such grids emphasize only horizontal and vertical lines dis- tracting the observer from seeing the overall picture. To overcome such potential drawback, old masters placed tiles emphasizing the strong edges of the main subject to be rep- resented. In our context we are not interested into physical design of a mosaic work (e.g., cementing materials, etc.), but in the way that the individual mosaic pieces (e.g., tesserae) are laid down. By using different materials and/or com- bining the tesseraes in various ways, many different artistic styles and effects can be obtained [2]. The general ”flow”of the mosaic is known as ”andamento”. The typical ancient mosaics, today available in Computer Graphics, have a specific categorization in the field of Cul- tural Heritage. The old term ”opus” is used to describe the overall appearance of the mosaic. In particular the imple- mented techniques until now are the ”opus musivum” and the ”opus vermiculatum”. ”Opus vermiculatum”, from the Latin word ”worm”, refers to lines (e.g., two or three) of tiles that snake around a feature in the mosaic appearing as