Towards a three-dimensional cost-effective registration of the archaeological heritage

Terrestrial laser scanning and close range photogrammetry for 3D archaeological documentation: the Upper Palaeolithic Cave of Parpalló as a case study

Structure from Motion (SfM) generates high-resolution topography and coregistered texture (color) from an unstructured set of overlapping photographs taken from varying viewpoints, overcoming many of the cost, time, and logistical limitations of Light Detection and Ranging (LiDAR) and other topographic surveying methods. This paper provides the first investigation of SfM as a tool for mapping fault zone topography in areas of sparse or low-lying vegetation. First, we present a simple, affordable SfM workflow, based on an unmanned helium balloon or motorized glider, an inexpensive camera, and semiautomated software. Second, we illustrate the system at two sites on southern California faults covered by existing airborne or terrestrial LiDAR, enabling a comparative assessment of SfM topography resolution and precision. At the first site, an ∼0.1 km 2 alluvial fan on the San Andreas fault, a colored point cloud of density mostly >700 points/m 2 and a 3 cm digital elevation model (DEM) and orthophoto were produced from 233 photos collected ∼50 m above ground level. When a few global positioning system ground control points are incorporated, closest point vertical distances to the much sparser (∼4 points/m 2 ) airborne LiDAR point cloud are mostly 530 points/m 2 and a 2 cm DEM and orthophoto were produced from 450 photos taken from ∼60 m above ground level. Closest point vertical distances to existing terrestrial LiDAR data of comparable density are mostly

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Rapid mapping of ultrafine fault zone topography with structure from motion

Historic bridge modelling using laser scanning, ground penetrating radar and finite element methods in the context of structural dynamics

This article modifies an old archaeological adage—“excavation is destruction”—to demonstrate how advances in archaeological practice suggest a new iteration: “excavation is digitization.” Digitization, in a fully digital paradigm, refers to practices that leverage advances in onsite, image-based modeling and volumetric recording, integrated databases, and data sharing. Such practices were implemented in 2014 during the inaugural season of the Kaymakci Archaeological Project (KAP) in western Turkey. The KAP recording system, developed from inception before excavation as a digital workflow, increases accuracy and efficiency as well as simplicity and consistency. The system also encourages both practical and conceptual advances in archaeological practice. These involve benefits associated with thinking volumetrically, rather than in two dimensions, and a connectivity that allows for group decision-making regardless of group location. Additionally, it is hoped that the system's use of almost entirely ...

Excavation is Destruction Digitization: Advances in Archaeological Practice

Documentation of cultural heritage using digital photogrammetry and laser scanning

The determination of object coordinates based on direct sensor orientation is an extrapolation from the projection centers to the ground coordinate system. Like any extrapolation, it is sensitive to random and systematic errors, as well as, to improper data handling. Direct sensor orientation is based on the combination of an Inertial Measurement System (IMU) and GPS. The GPS antenna, the IMU, and the imaging sensor are located in different positions, and the latter two have different orientations. Therefore, the calibration of all sensors and the relation between the sensors is of vital importance for precise ground positioning. The system calibration includes the determination of the boresight misalignment, the interior camera orientation, and the GPS antenna offset. A rigorous mathematical model is required. The inner orientation of the camera used has to be determined under flight conditions to achieve sufficient results. In this paper, the influence of the system calibration to the direct sensor orientation and improper data handling will be shown.

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Influence of System Calibration on Direct Sensor Orientation

Georeferencing is one of the most important tasks in photogrammetry. Traditionally it has been achieved indirectly using the well-known method of aerial triangulation. With the availability of integrated GPS and inertial measurement units (IMU), this situation changed. Direct determination of exterior orientation is now possible. Today, direct and integrated sensor orientation is used for a wide range of sensors including lidar and SAR, as well as for digital line scanner systems and aerial cameras. This paper investigates the performance of direct and integrated sensor orientation for large scale mapping using the data-set of the ‘‘Integrated Sensor Orientation’’ test of the European Organisation for Experimental Photogrammetric Research (OEEPE—now known as EuroSDR). The concept, potential, problems and solutions of direct and integrated sensor orientation are discussed.

Resume

La determination des positions est l'une des tâches les plus importantes de la photogrammetrie. On y est parvenu indirectement en utilisant de facon classique la methode bien connue de l'aerotriangulation. L'existence de dispositifs de mesures integrant les systemes GPS et inertiels (IMU) a change la situation. Il est maintenant possible de determiner directement les orientations externes. On peut ainsi mesurer actuellement l'orientation de toute une gamme de capteurs comprenant les lidars, les radars a synthese d'ouverture, les cameras aeriennes ainsi que les systemes numeriques a balayage lineaire. On examine dans cet article les possibilites de ces systemes d'orientation directe a capteurs integres, pour la cartographie a grande echelle, a l'aide du jeu de donnees etabli par l'OEEPE (connue desormais sous le nom d'EuroSDR) pour son essai d’«orientation par capteur integre». On analyse egalement l'ensemble de la conception, du potentiel, des problemes et des solutions de cette orientation directe a capteurs integres.

Zusammenfassung

Die Bestimmung der Relation von Bild- zu Objektkoordinaten ist eine Grundvoraussetzung der Photogrammetrie, die traditionell durch Blockausgleichung bestimmt wird. Dieses hat sich durch Kombination von GPS und inertialen Messeinheiten (IMU) geandert, sie ermoglicht jetzt die direkte Bestimmung der auseren Orientierung. Heute werden die direkte und die integrierte Sensororientierung fur viele Anwendungen, wie fur Laserscanning, SAR, Zeilenscanner aber auch fur die Orientierung von Luftbildkameras benutzt. Anhand eines Testdatensatzes der OEEPE—heute umbenannt in EuroSDR—wird das Potenzial der direkten und der integrierten Sensororientierung untersucht. Das Konzept, das Genauigkeitspotenzial, vorhandene Probleme und deren Losung werden dargestellt.

Resumen

La georreferenciacion es una de las tareas mas importantes de la fotogrametria. Tradicionalmente se ha realizado de forma indirecta usando el conocido metodo de la aerotriangulacion. La situacion ha cambiado actualmente gracias a los sistemas GPS integrados y las unidades de medida inercial (IMU) que permiten la determinacion directa de la orientacion exterior. La orientacion directa e integrada se usa hoy en dia para un amplio abanico de sensores, incluyendo Lidar y SAR, asi como en escaneres lineales digitales y camaras aerotransportadas. Este articulo investiga sobre los resultados de la orientacion directa e integrada de sensores para cartografia a escala grande a partir de los datos del proyecto ‘‘Integrated Sensor Orientation’’ de la European Organization for Experimental Photogrammetric Research (OEEPE)—ahora denominada EuroSDR—y se reflexiona acerca del concepto, el potencial, los problemas y las soluciones de la orientacion directa e integrada de sensores.

Direct Sensor Orientation for Large Scale Mapping-Potential, Problems, Solutions

This paper presents an automatic building extraction approach using LiDAR data and aerial photographs from a multi-sensor system positioned at the same platform. The automatic building extraction approach consists of segmentation, analysis and classification steps based on object-based image analysis. The chessboard, contrast split and multi-resolution segmentation methods were used in the segmentation step. The determined object primitives in segmentation, such as scale parameter, shape, completeness, brightness, and statistical parameters, were used to determine threshold values for classification in the analysis step. The rule-based classification was carried out with defined decision rules based on determined object primitives and fuzzy rules. In this study, hierarchical classification was preferred. First, the vegetation and ground classes were generated; the building class was then extracted. The NDVI, slope and Hough images were generated and used to avoid confusing the building class with other classes. The intensity images generated from the LiDAR data and morphological operations were utilized to improve the accuracy of the building class. The proposed approach achieved an overall accuracy of approximately 93% for the target class in a suburban neighborhood, which was the study area. Moreover, completeness (96.73%) and correctness (95.02%) analyses were performed by comparing the automatically extracted buildings and reference data.

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Automatic building extraction using LiDAR and aerial photographs

Three-dimensional (3D) spatial information is crucial for improving the quality of human life through urban planning and management, and it is widely utilized due to its rapid, periodic and inexpensive acquisition. In this context, extraction of digital surface and elevation models (DSM and DEM) is a significant research topic for space-borne optical and synthetic aperture radar (SAR) remote sensing. The DSMs include visible features on the earth’s surface such as vegetation, forest and elevated man-made objects, while DEMs contain only the bare ground. In this paper, using TerraSAR-X (TSX) high resolution Spotlight (HS) images, high-resolution interferometric DEM generation in a part of Istanbul urban area is aimed. This is not an easy task because of SAR imaging problems in complex geometry of urban settlements. The interferometric processing steps for DSM generation were discussed including critical parameters and thresholds to improve the quality of the final product and a 3 m gridded DSM was generated. The DSM-DEM conversion was performed by filtering and the quality of generated DEM was verified against a reference DEM from stereo photogrammetry with 3 m original grid spacing. The achieved root mean square error of height differences (RMSZ) varies from 7.09 to 8.11 m, depending on the terrain slope. The differential DEM, illustrates the height differences between generated DEM and the reference DEM, was generated to show the correlation between height differences and the coherence map. Finally, a perspective view of test area was created draping extracted DEM and a high-resolution IKONOS panchromatic image.

Naci Yastikli

Papers

Documentation of cultural heritage using digital photogrammetry and laser scanning

Influence of System Calibration on Direct Sensor Orientation

Direct Sensor Orientation for Large Scale Mapping-Potential, Problems, Solutions

Automatic building extraction using LiDAR and aerial photographs

DEM Extraction in Urban Areas Using High-Resolution TerraSAR-X Imagery