Novas metodologias não-invasivas de prospecção arqueológica: o contributo das tecnologias geo-espaciais

The aim of this paper is to give an overview of the new survey methods in Archaeology based on the application of geospatial technologies. We will pay particular attention to a concrete remote sensing technology: Light Detection and Ranging (liDAR).Pretende-se com este trabalho apresentar uma breve síntese acerca dos novos métodos de prospecção em Arqueologia baseados em tecnologias geo-espaciais. Dedicaremos particular atenção a uma tecnologia concreta de detecção remota: Light Detection and Ranging (liDAR)

Terrestrial Laser Scanning for Preserving Cultural Heritage: Analysis of Geometric Anomalies for Ancient Structures

Identifying the overhang, progressive changes of inclination, differential movements of the structure and detailing the study of structural elements are just some examples of the many fundamental information for structural engineers. Those data are required to study and analyze the behavior of a structure with the purpose to assess the stability . Laser scanning appears to be the best technology to provide an effective solution to those requirements. Surveying by means of a terrestrial laser scanner (TLS), allows to detect a huge number of information with relatively short time and high accuracy. Those data, then, do not necessarily need to be used to reconstruct the three dimensional surface model. Just analyzing the point clouds, interesting information along with useful products can be obtained in order to draw some considerations about the investigated structure. This research aims to suggest a new philosophy for using TLS in a diagnostic perspective in order to study structures along with their actual dimensions, their stability and so on. This new approach, characterized by a well- advanced vision, is really different from the traditional one because of the engineering point of view with respect to the usual application of TLS. Traditionally, indeed, laser scanning is chosen for artistic and architectural studies and the resulting three-dimensional model represents what often is of concern.The research focuses on the Cathedral of Modena, one of the most important pieces of Romanesque culture in Europe (UNESCO World Heritage List since 1997). The overall motivation of this research is to preserve the cultural heritage we are responsible for, as long as spectators. Thus, the final purpose is to illustrate the methodology to compute anomalies in structural geometry by means of TLS in order to provide an accurate description of the structure that is particularly useful for structural engineers, architects and art historians. Both outdoor as well as indoor TLS surveys were performed. The geometry of the structure was properly described by analyzing point clouds; specific measurements were focused on constituent elements with the aim of detecting anomalies of the geometric configuration. Geometric anomalies might be read as the result of deformations occurred in the past or as future deformations due to an abnormal geometric configuration. Investigations about the identified anomalies will be presented together with differential movements obtained by high precision leveling focused on a network of benchmarks that were installed along the outside perimeter. The integration of independent techniques allows to check for consistency of results

A Survey of Geometric Analysis in Cultural Heritage

We present a review of recent techniques for performing geometric analysis in cultural heritage (CH) applications. The survey is aimed at researchers in the areas of computer graphics, computer vision and CH computing, as well as to scholars and practitioners in the CH field. The problems considered include shape perception enhancement, restoration and preservation support, monitoring over time, object interpretation and collection analysis. All of these problems typically rely on an understanding of the structure of the shapes in question at both a local and global level. In this survey, we discuss the different problem forms and review the main solution methods, aided by classification criteria based on the geometric scale at which the analysis is performed and the cardinality of the relationships among object parts exploited during the analysis. We finalize the report by discussing open problems and future perspectives

Algoritma penurasan data lidar untuk penjanaan model ketinggian digital bagi kawasan tropika

Filtering technique and the environmental factors are among the main factors, which affect Digital Elevation Model (DEM) accuracy obtained from the Light Detection and Ranging (LiDAR) data especially for steep area and covered by vegetation. Intensive research of LiDAR data filtering in tropical area is very limited and the improvement of the filtering technique using the environmental factor is very much needed. The purpose of this research is to improve the existing filtering techniques such as Progressive Morphology (PM) for DEM generation in the area covered by tropical vegetation. Initial test has been done by evaluating the filtering techniques such as PM, Adaptive Triangular Irregular Network (ATIN) and Elevation Threshold with Expand Window (ETEW) on the LiDAR data over Pekan, Pahang with slope between 0o and l0o. LiDAR DEM accuracy that was calculated based on ground reference point in mixed forest area shows that PM and ETEW filtering methods have produced minor RSME errors of A.226m and 0.192m compared to ATIN with 0.235m. Subsequent test was conducted for rubber area with slope value between 0o to 15o. The results show low RMSE error of 0.660m, 0.699m and A.717m for PM, ETEW and ATIN respectively. This shows that the slope parameter has an impact on the accuracy of the DEM, These results also demonstrate that the PM technique provides the highest accuracy. However the slope value in PM technique was based on constant value and applied to the entire LiDAR data. Compared to other filtering techniques, PM techniques provide more convenient way of improving the slope value. Improvement of PM filtering technique has been made by taking into account the actual slope value parameter and the revised method named AdapMorf algorithm. AdapMorf filtering technique was evaluated based on the slope gradient of the earth surface with the accuracy of the DEM error was evaluated for each area (i.e. mixed forest, rubber and oil palm) with slope between 0o and l5o. Three categories of assessments were carried out for each landcover and each category has a series of tests. DEM results were analyzed using RMSE error and the calculation of Type I and Type II errors. The best DEM's accuracy for AdapMorf by the types of landcover are 0.650m, 0.520m and 0.604m for mixed forests, rubber and oil palm respectively. The lowest results for Type I error are29.l7o/o,31.760/o and 35.l3Yo for rubber, mixed forest and oil palm respectively. The results for Type II error are 0.05oh,0.06% and 0.2lYs for rubber, mix forest and oil palm respectively. Due to the Type I error for AdapMorf was relatively high, the filtering technique was improved by introducing TyMof filtering technique. The tests were canied out and the results obtained show improvement in DEM's accuracy with RMSE for rubber and mixed forest are A.472m and 0.582m respectively. The Type I error for mixed forest and rubber are 28.90Yo and 19.29o/o respectively. This study shows that AdapMorf and TyMof filtering techniques were able to generate DEM with error smaller than the previous techniques for area with slope between 0o and 15". As a conclusion, AdapMorf and TyMof filtering techniques have shown that it can produce better quality of DEM for steep area and vegetated cover of tropical forest

Algoritma penurasan data lidar untuk penjanaan model ketinggian digital bagi kawasan tropika

Filtering technique and the environmental factors are among the main factors, which affect Digital Elevation Model (DEM) accuracy obtained from the Light Detection and Ranging (LiDAR) data especially for steep area and covered by vegetation. Intensive research of LiDAR data filtering in tropical area is very limited and the improvement of the filtering technique using the environmental factor is very much needed. The purpose of this research is to improve the existing filtering techniques such as Progressive Morphology (PM) for DEM generation in the area covered by tropical vegetation. Initial test has been done by evaluating the filtering techniques such as PM, Adaptive Triangular Irregular Network (ATIN) and Elevation Threshold with Expand Window (ETEW) on the LiDAR data over Pekan, Pahang with slope between 0o and l0o. LiDAR DEM accuracy that was calculated based on ground reference point in mixed forest area shows that PM and ETEW filtering methods have produced minor RSME errors of A.226m and 0.192m compared to ATIN with 0.235m. Subsequent test was conducted for rubber area with slope value between 0o to 15o. The results show low RMSE error of 0.660m, 0.699m and A.717m for PM, ETEW and ATIN respectively. This shows that the slope parameter has an impact on the accuracy of the DEM, These results also demonstrate that the PM technique provides the highest accuracy. However the slope value in PM technique was based on constant value and applied to the entire LiDAR data. Compared to other filtering techniques, PM techniques provide more convenient way of improving the slope value. Improvement of PM filtering technique has been made by taking into account the actual slope value parameter and the revised method named AdapMorf algorithm. AdapMorf filtering technique was evaluated based on the slope gradient of the earth surface with the accuracy of the DEM error was evaluated for each area (i.e. mixed forest, rubber and oil palm) with slope between 0o and l5o. Three categories of assessments were carried out for each landcover and each category has a series of tests. DEM results were analyzed using RMSE error and the calculation of Type I and Type II errors. The best DEM's accuracy for AdapMorf by the types of landcover are 0.650m, 0.520m and 0.604m for mixed forests, rubber and oil palm respectively. The lowest results for Type I error are29.l7o/o,31.760/o and 35.l3Yo for rubber, mixed forest and oil palm respectively. The results for Type II error are 0.05oh,0.06% and 0.2lYs for rubber, mix forest and oil palm respectively. Due to the Type I error for AdapMorf was relatively high, the filtering technique was improved by introducing TyMof filtering technique. The tests were canied out and the results obtained show improvement in DEM's accuracy with RMSE for rubber and mixed forest are A.472m and 0.582m respectively. The Type I error for mixed forest and rubber are 28.90Yo and 19.29o/o respectively. This study shows that AdapMorf and TyMof filtering techniques were able to generate DEM with error smaller than the previous techniques for area with slope between 0o and 15". As a conclusion, AdapMorf and TyMof filtering techniques have shown that it can produce better quality of DEM for steep area and vegetated cover of tropical forest

Detection of archeological sites by means of ULS/ALS

Nové technologie umožňují archeologům prozkoumávat místa, která dříve byla jejich zrakům skryta. Zejména zalesněné oblasti byly dříve pro archeologický průzkum velice obtížným terénem. V posledních letech však technologie LiDARu tento problém mění spíše ve výhodu,vzhledem ke konzervační schopnosti lesa. Cílem této práce je ověřit možnosti detekce mohylových pohřebišť v zalesněném terénu z LiDARových dat pořízených z UAV nosiče a z letadla. V práci bude úspěšnost detekce těchto dvou typů dat vzájemně vizuálně porovnána v rámci jednotlivých, v archeologii běžně používaných vizualizačních technik. Výsledky budou dále porovnány s terénním měřením.New technologies allow archaeologists to explore places that were previously hidden from their view. In recent years, however, LiDAR technology has turned this problem more into an advantage, given by the preservative capacity of the forest. The aim of this work is to verify the possibilities of detection of mound burial grounds in wooded terrain with the help of LiDAR data obtained from an UAV and from an aircraft. In this work, the success of the detection of these two types of data will be visually compared by means of visualization techniques commonly used in archeology. The results will be further compared with field measurements.Department of Applied Geoinformatics and CartographyKatedra aplikované geoinformatiky a kartografieFaculty of SciencePřírodovědecká fakult

Lotniczy skaning laserowy w polskiej archeologii. Czy w pełni wykorzystywany jest potencjał prospekcyjny metody?

Airborne Laser Scanning (ALS) is an advanced method of archaeological prospection. One can easily spot an increasing number of applications of LiDAR data within Polish archaeology. Due to that fact it is important to understand the prospective potential of the method as well as subjective character of generated information. The aim of this paper is to describe analytical and interpretative aspects of ALS. Application of LiDAR data is characterised by various processes which lead to the reduction of information about the past. Those processes will be identified and a number of practical solutions aiming to prevent them will be presented. The paper, based on a critical analysis of the procedurę of data acquisition and processing as well as creation of the final products, shows how important is knowledge of subjective character of data, tools and techniques during usage of ALS for archaeological purposes