La recuperación de los punzones de rúbrica de la terra sigillata hispánica del alfar romano de Isturgi (Los Villares de Andújar, Jaén) a partir de su digitalización, reconstrucción e impresión 3D

Abstract

[EN] Terra sigillata is one of the most important and well-known ceramic types of the Roman Empire. These tableware productions began to become generalized from the 1st century AD, characterized by the habitual presence of what is known as sigillum, a kind of stamped mark that identified the pottery ( officina ) where they were produced. Currently, the information given by the stamps on vessels becomes one of the main sources for the reconstruction of the social and economic structure of terra sigillata manufacture.In the case of the terra sigillata produced in the Iberian Peninsula, both the smooth-walled and the decorated vessels are distinguished by habitually incorporating this rubric/signature, which was made using a stamp-punch. While in smooth-walled vessels this rubric is usually located on the inner bottom of the container, in the case of decorated one, which used to be produced using negative ceramic moulds; the dynamics can be somewhat more complex. At any rate, and unlike the ceramic itself, which becomes a very common object in the archaeological context, the instruments with which these productions used to be marked are very difficult to find. Indeed, they are very rare elements in archaeological excavations or museum collections. An example of this dynamic is the pottery district of Isturgi (Los Villares de Andújar, Jaén, Spain), which became an important producer of terra sigillata around the 1st and 2nd centuries AD. In this large potter complex, despite numerous systematic excavation campaigns since the early 1970s, no original stamp-punch has been recovered yet.In this regard, the strong development of tools for digitization, analysis, virtual reconstruction and new printing devices has brought important benefits for the study of archaeological heritage in general and ceramic studies in particular. Technologies that, although most of them are already well established in our discipline, continue to generate novel results of great scientific interest. However, to take full advantage of their potential, these technologies should not be used in isolation, but must be combined in synergistic methodological flows that we can carry out from the joint use of various computer software. Only in this way, we can effectively recreate elements and objects that, due to their intrinsic value or the fragility of their nature, do not usually appear in the archaeological record.In the present work, a new methodological workflow is proposed through which to obtain data that would allow the coherent reconstruction of the appearance and operation of these fragile instruments. With this objective in mind, we made a selection of nine smooth-walled vessels of terra sigillata isturgitana in which the potters had recorded their work by means of epigraphic and anepigraphic marks. For this reason, various computerized procedures were applied in a systematic way to each of these selected case studies. First, Structure from Motion (SfM) photogrammetry for digitizing these sigilla. Second, computational photography methods such as Virtual Reflectance Transformation Imaging (V-RTI) or raster images such as Digital Elevation Maps (DEM) to improve the visualization of the most deteriorated rubrics. Third, digital modelling and sculpting to generate reliable reconstructive hypotheses of a digital nature. Finally, we use Fused Deposition Modelling (FDM), the most common 3D printing method, to materialize these results into high-resolution and low-cost polylactic acid (PLA) replicas.Through all this workflow described in the previous lines, we not only seek the generation of new data that will benefit the archaeological discipline, but that all this knowledge also results in a direct benefit for the bulk of society. Jointly, the technologies of digitization and rapid prototyping have proven to be extremely useful tools for making archaeological heritage truly accessible to everyone, regardless of the situation, needs or geographic location.

[ES] La terra sigillata es, sin duda alguna, uno de los tipos cerámicos más importantes y conocidos de un incipiente imperio romano. Este tipo de producciones cerámicas están caracterizadas por la presencia habitual de lo que se conoce como sigillum, una suerte de marca que identificaba al alfar u officina donde eran producidas. A diferencia de la propia cerámica, un objeto muy habitual en el contexto arqueológico, los instrumentos con los que se solían marcar dichas producciones resultan muy complicados de localizar, convirtiéndose en elementos muy poco frecuentes en las excavaciones arqueológicas o en los fondos de museos. Un claro ejemplo de esta dinámica es el barrio alfarero de Isturgi (Los Villares de Andújar, Jaén, España), donde tras numerosas campañas de excavación aún no se ha recuperado ningún punzón original. A este respecto, el fuerte desarrollo de las herramientas de digitalización, análisis, reconstrucción virtual y los nuevos dispositivos de impresión ha supuesto importantes beneficios para al estudio del patrimonio arqueológico en general. Con el objetivo de aprovechar al máximo su potencial, estas técnicas se suelen combinar en flujos metodológicos sinérgicos que podemos materializar a partir del uso conjunto de varios softwares informáticos. Gracias a ello, podemos recrear de forma efectiva elementos y objetos que, por su valor o naturaleza, no suelen aparecer de forma habitual en el registro arqueológico. En el presente trabajo se propone, por tanto, un nuevo flujo metodológico que combina herramientas ya asentadas como la fotogrametría Structure from Motion, los métodos de fotografía computacional como la Reflectance Transformation Imaging virtual (V-RTI), el modelado 3D o la impresión 3D. Todo ello, con un claro objetivo en mente, recrear los punzones y marcas de entalle empleados para rubricar la vajilla fina de mesa procedente del yacimiento romano de Los Villares de Andújar (Jaén).