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Yayın Determining pull - out deformations of bonded metal anchors embedded in concrete by means of photogrammetry(International Society for Photogrammetry and Remote Sensing, 2012) Avşar, Edip Özgür; Altan, Mehmet Orhan; Doğan, Umut Anıl; Akça, Mehmet DevrimChemical anchorages are applied in many engineering implementations, particularly strengthening of reinforced concrete structures. During strengthening procedure; chemical anchorages should be tested, since they supply to transfer the load between existing construction elements and newly added elements. Therefore; the study of the quality of chemical anchorages is an important issue in construction materials science. In this context; the most important experiment is to determine the pull-out loads of embedded anchorage reinforcement by applying axial loads. In this study; it is aimed to determine the displacements of steel reinforcements, embedded into concrete by using chemical anchorages, while applying axial pulling loads. In order to determine the displacements and load - deformation graphs; starting conditions and every 10 bar pressure applied conditions of the steel reinforcements were captured by the cameras. The obtained images were evaluated by using photogrammetric software. Based on the photogrammetric post-processing results, the load - deformation graphs were plotted and the loads at loss of adhesion were determined.Yayın Quality assessment of 3D building data(Wiley-Blackwell Publishing, 2010-12) Akça, Mehmet Devrim; Freeman, Mark; Sargent, Isabel; Gruen, Armin W.Three-dimensional building models are often now produced from lidar and photogrammetric data. The quality control of these models is a relevant issue both from the scientific and practical points of view. This work presents a method for the quality control of such models. The input model (3D building data) is co-registered to the verification data using a 3D surface matching method. The 3D surface matching evaluates the Euclidean distances between the verification and input data-sets. The Euclidean distances give appropriate metrics for the 3D model quality. This metric is independent of the method of data capture. The proposed method can favourably address the reference system accuracy, positional accuracy and completeness. Three practical examples of the method are provided for demonstration.Yayın Photogrammetric monitoring of an artificially generated landslide(Copernicus GmbH, 2011-05-08) Akça, Mehmet Devrim; Gruen, Armin W.; Askarinejad, Amin; Springman, Sarah MarcellaAccording to pre-planned schedules, a series of two artificial rainfall events were applied to a forested slope in Ruedlingen, northern Switzerland. The experiments were conducted in autumn 2008 and spring 2009, the second of which resulted in mobilising about 130 m3 of debris. Both experiments were monitored by a photogrammetric camera network in order to quantify spatial and temporal changes. A 4-camera arrangement was used for the image acquisition. The cameras operated at a data acquisition rate of circa 8 frames per second (fps). Image measurements were made using the Least Squares image matching method, which was implemented in an in-house developed software package (BAAP) to compute 3D coordinates of the target points. The surface deformation was quantified by tracking the small (ping-pong and tennis) balls pegged into the ground. The average 3D point-positioning precision of ±1.6 cm was achieved in the first experiment and ±1.8 cm in the second experiment.
