Integrated 3D Geomatics for archaeology : case study Malta

Abstract

This article discusses the integrated use of different 3D geomatics techniques: digital aerial photogrammetric restitution, advanced SBAS GNSS and robotized total station measurements. The aim is the realization of both an orthophoto plan and a digital elevation models (DEM) of the whole research area. Quality control, e.g. by applying accuracy analysis of the DEMs, is he- reby of vital importance. The integration of these different techniques and the resulting final prod- ucts are used for an important archaeological campaign on the island of Malta. This successful case study can be representative for many archaeological applications where high quality reference data are required for large areas. Especially when multiple archaeological sites are spread over the landscape, it is essential to have orthophotos or a vector dataset, covering the areas of interest. An orthophoto plan and DEM with an area of ca. 20 km2 on the north western part of Malta (Valley of Bidnija and Burmarrad) have been constructed by the authors. Several Punic and Roman sites are located in this area and are documented by researchers of Ghent University in collaboration with the University of Malta and the Superintendence of Cultural Heritage Malta. The project is fi- nanced by the Flemish Fund for Scientific Research and entitled “Malta Survey Project 2008 (MSP2008). The orthophoto plan and DEM make it possible to put separate campaigns in a wider spatial context, which enables the detection of possible horizontal relations between the sites. Moreover, combining documented archaeological sites with a DEM enables the analysis of vertical relations. This explains the necessity of elevation data in archaeological research of e.g. water household management on ancient sites. In many cases, no digital elevation models with the de- sired quality are available. Therefore, the necessary DEM has to be measured and computed for the specific project. The final joined DEM for the whole area of this project is based on 10 photo- grammetric stereo couples, with a scale of 1:10 000 and a resolution of 25 cm, and has been geore- ferenced by GNSS (CNAV). These stereo couples have been processed using the photogrammetric software VirtuoZo. The quality analysis of the DEM, based on overlapping zones between differ- ent orthophotos, is executed by the point processing software WinTopo. Different derivative prod- ucts from the orthophoto plan and DEM - like contour line maps, 3D models, hillshade maps and others - will serve in further analysis of the ancient sites on the island of Malta.