Mark Vetter

Low-Cost Real-Time 3D Reconstruction of Large-Scale Excavation Sites

The 3D reconstruction of archeological sites is still an expensive and time-consuming task. In this article, we present a novel interactive, low-cost approach to 3D reconstruction and compare it to a standard photogrammetry pipeline based on high-resolution photographs. Our novel real-time reconstruction pipeline is based on a low-cost, consumer-level hand-held RGB-D sensor. While scanning, the user sees a live view of the current reconstruction, allowing the user to intervene immediately and adapt the sensor path to the current scanning result. After a raw reconstruction has been acquired, the digital model is interactively warped to fit a geo-referenced map using a handle-based deformation paradigm. Even large sites can be scanned within a few minutes, and no costly postprocessing is required. The quality of the acquired digitized raw 3D models is evaluated by comparing them to actual imagery, a geo-referenced map of the excavation site, and a photogrammetry-based reconstruction. We made extensive tests under real-world conditions on an archeological excavation in Metropolis, Ionia, Turkey. We found that the reconstruction quality of our approach is comparable to that of photogrammetry. Yet, both approaches have advantages and shortcomings in specific setups, which we analyze and discuss.

Low-cost real-time 3D reconstruction of large-scale excavation sites using an RGB-D camera

In this paper, we present an end-to-end pipeline for the online reconstruction of large-scale outdoor environments and tightly confined indoor spaces using a low-cost consumer-level hand-held RGB-D sensor. While scanning, the user sees a live view of the current reconstruction, allowing him to intervene immediately and to adapt the sensor path to the current scanning result. After a raw reconstruction has been acquired, we interactively warp the digital model to fit a geo-referenced map using a handle based deformation paradigm. Even large sites can be scanned within a few minutes, and no costly postprocessing is required. We developed our prototype in cooperation with researchers from the field of ancient history and geography and extensively tested the system under real world conditions on an archeological excavation in Metropolis, Ionia, Turkey. The quality of the acquired digitized raw 3D models is evaluated by comparing them to actual imagery and a geo-referenced map of the excavation site. Our reconstructions can be used to take virtual measurements that are often required in research and are the basis for a digital preservation of our cultural heritage. In addition, digital models are a helpful tool for teaching as well as for edutainment purposes making such information accessible to the general public.

The Historical Distribution of Main Malaria Foci in Spain as Related to Water Bodies

The possible connectivity between the spatial distribution of water bodies suitable for vectors of malaria and endemic malaria foci in Southern Europe is still not well known. Spain was one of the last countries in Western Europe to be declared free of malaria by the World Health Organization (WHO) in 1964. This study combines, by means of a spatial-temporal analysis, the historical data of patients and deceased with the distribution of water bodies where the disease-transmitting mosquitos proliferate. Therefore, data from historical archives with a Geographic Information System (GIS), using the Inverse Distance Weighted (IDW) interpolation method, was analyzed with the aim of identifying regional differences in the distribution of malaria in Spain. The reasons, why the risk of transmission is concentrated in specific regions, are related to worse socioeconomic conditions (Extremadura), the presence of another vector (Anopheles labranchiae) besides A. atroparvus (Levante) or large areas of water bodies in conditions to reproduce theses vectors (La Mancha and Western Andalusia). In the particular case of Western Andalusia, in 1913, the relatively high percentage of 4.73% of the surface, equal to 202362 ha, corresponds to wetlands and other unhealthy water bodies. These wetlands have been reduced as a result of desiccation policies and climate change such as the Little Ice Age and Global Climate Change. The comprehension of the main factors of these wetland changes in the past can help us interpret accurately the future risk of malaria re-emergence in temperate latitudes, since it reveals the crucial role of unhealthy water bodies on the distribution, endemicity and eradication of malaria in southern Europe.

Earthquakes in History – Ways to Find out About the Seismic Past of a Region

The onset of the 21st century has brought a new public awareness of natural hazards. Recent catastrophic events like the 2004 tsunami in Asia or the 2005 flooding of New Orleans have made it not only to the headlines in news publications around the globe but have also contributed to a more profound desire to accumulate knowledge about natural hazards in general among people all over the world. Earthquake research belongs to the most fascinating (albeit problematic) topics in the field of natural hazard research. Hardly any other hazard claims more lives, destroys more values and can lead to catastrophic aftereffects (as can be seen when looking at the 2011 earthquake with resulting tsunami and nuclear disaster in Japan). In most cases scientists are not able to forecast when and where an earthquake may take place, but only the approximate region and the probability, not the precise date and the magnitude. Geoscientists therefore by and large concentrate on assessing and mapping regions that experienced earthquakes in the past. As a consequence, the description of past earthquakes is of utmost importance for a reliable projection of future earthquakes. Several ways exist to sum up details about historical earthquakes, the most important of which was the analysis of written documents in premeasurement times (see Fig. 1). From the 19th century onwards the installation of seismometers has considerably improved the situation and nowadays the analysis of a new earthquake relies almost completely on measurements. This paper strives to offer a short introduction to the following aspects:  Historical earthquakes and their reception history  Ancient attempts to forecast and measure earthquakes  Early modern attempts to collect written information on earthquake events  Early modern earthquake catalogues in Europe  The application of early seismometers  The expansion of a seismometer network  Open source ways to collect earthquake information The paper will concentrate on (but not limit itself to) German attempts in the aforementioned aspects, including a short overview of the current state of research. Of special importance in this context is the Bavarian BASE-project, which serves as a role model for a modern and complete collection of historical earthquake data