Abstract:
3D geometric modeling consists of representing geometric and spatial relationships of volumetric objects. We think it could be helpful in the context of archaeological excavation units representation and analysis. This article presents a procedure developed to generate 3D models from GPS positions taken at the top and the bottom of the excavation units boundaries on the archaeological site of Tell ‘Acharneh (Syria). It shows and discusses two geometrical modeling approaches (voxel and tetrahedral) used in the Gocad 3D modeling tool. Once excavation units are geometrically modeled, it is possible to refer them within a trench or the entire archaeological site, to handle them in various ways (zoom, rotation, translation), to perform on them 3D spatial analysis such as volumetric calculus or intersection computation, to make various kinds of queries such as to find out excavation units that have a certain number of artefacts, to generate sections anywhere in the 3D model, and finally to publish it with VRML (Virtual Reality Modular Language). As well as improving data analysis techniques, we think that if this 3D modeling operation can be done during the excavation, it could greatly help archaeologists to plan more efficiently their daily excavation strategy.
3D geometric modeling consists of representing geometric and spatial relationships of volumetric objects. We think it could be helpful in the context of archaeological excavation units representation and analysis. This article presents a procedure developed to generate 3D models from GPS positions taken at the top and the bottom of the excavation units boundaries on the archaeological site of Tell ‘Acharneh (Syria). It shows and discusses two geometrical modeling approaches (voxel and tetrahedral) used in the Gocad 3D modeling tool. Once excavation units are geometrically modeled, it is possible to refer them within a trench or the entire archaeological site, to handle them in various ways (zoom, rotation, translation), to perform on them 3D spatial analysis such as volumetric calculus or intersection computation, to make various kinds of queries such as to find out excavation units that have a certain number of artefacts, to generate sections anywhere in the 3D model, and finally to publish it with VRML (Virtual Reality Modular Language). As well as improving data analysis techniques, we think that if this 3D modeling operation can be done during the excavation, it could greatly help archaeologists to plan more efficiently their daily excavation strategy.
This article is about a procedure that is able to generate 3D models from PGS positions taken at the top and bottom of the excavation units boundaries. It discusses two geometrical modelling approaches (voxel and tetrahedron) that are used by GoCAD 3D modelling tool. Once the geometric models are produced, it is possible to manipulate them in various and perform various kinds of queries. The geometrical model can also be published is VRML.
ResponderEliminarThe main objectives of this work are (1) to improve data analysis techniques and (2) to help archaeologists to plan more efficiently their excavation strategy.
Almost all archaeological excavations use the concept of “excavation units”, also known as “stratigraphic units”, since most archaeological sites are composed of several superimposed layers of archaeological deposits. A stratigraphic unit, which is the basic element of the recording procedure, is a 3D volumetric component of archaeological remains within a site under excavation. Although using this concept for years, archaeologists heavily rely on 2D representations of the stratigraphic units for analysis and interpretation purposes, as well as for publication. This is the main reason for unrealistic representation of archaeological section drawings.
For archaeologists, the spatial relationships of the excavation units are crucial. These topological relations are currently represented on a diagram matrix. However, since the matrix is based on conventional unrealistic icons arranged in 2D diagrams, it does not entirely meet the archaeologist’s needs. Therefore, displaying 3D excavation units could be an important aid in understanding stratigraphical relationships and identifying potential patterning. This would enable a virtual visit to the archaeological site, and so metric analysis could be performed, to validate interpretations or to formulate even new interpretations.
The spatial data acquisition was performed using first a theodolite (1998-2001), then a total station (2002) and finally a GPS Surveying System (2004). Using the GPS system, the data acquisition methodology consists of taking 3D points on top of each excavation unit and features (walls and pits), which are later recorded in a Microsoft Access Database. The bottom surface of the excavation unit corresponds to the top of one or more excavation units below. Besides spatial data, descriptive data such as artifacts, ecofacts or ceramics were acquired.
The modelling process uses GoCAD and comprises four different steps: (1) data interpretation, (2) surface object creation, (3) solid object creation and (4) object properties assignment. Regarding this project, the tetrahedron model has clear advantages over the voxel model. It is easy to handle, enables quick display and produces smaller files.
The main objective of this work is to develop a tool that helps the archaeologist to understand the archaeological site, to perform metric and topologic analysis on an excavation unit, to realise section cuttings anywhere on the solid model and to execute queries on qualitative and quantitative properties. Furthermore, this application is useful for helping the archaeological team in future excavation planning and to publish excavation data. An innovative aspect is to explore the excavation from a new perspective, using the 3D modelling as a tool to help field archaeologists to acquire new information. With a 3D model it is possible to quickly observe the relationship between excavation units from different angles.
The GoCAD software is used to reference excavation units within a trench and the whole of the archaeological site, to handle them in various ways, to perform on them volumetric, metric and spatial analysis, to generate sections anywhere on the 3D mode, and to publish it with VRML. Future work is to develop a topological structure of solid objects, automatic tools for 3D cleaning, 3D models with VRML interface for the web and an immersive reality experiment.