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Yildirim K.,Mus Alparslan University | Kucuk I.,YTU
Journal of the Franklin Institute | Year: 2016

Optimal piezoelectric vibration control problem for a Timoshenko beam is considered. The performance index function to be minimized by using the minimum level of the control voltage consists of a weighted quadratic function of displacement and velocity of the beam and also includes a quadratic functional of the control voltage function as a penalty term. The optimal control function is derived by means of a maximum principle which transforms the control problem to an initial-boundary-terminal value problem. In order to show the effectiveness of the control actuation, numerical results are given by MATLAB in table and graphical forms. © 2015 The Franklin Institute.


Gumusay M.U.,YTU | Ozdemir O.,Olcum Muhendislik | Bakirman T.,YTU
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2016

Web based geographic information systems (GIS) has great potential based on developments in internet and web technology. Web based GIS is a network based tool that takes advantage of internet with visualizing, analysing and accessing of distributed data and analysis functions. With the length of 30 kilometres, the Bosphorus provides an essential zone that offers great maritime traffic services. This shipping way which connects The Black Sea and The Mediterranean Sea through The Marmara Sea, has no alternative and it is substantial for economies of Black Sea countries. The Bosphorus is one of most important natural straits in the world handling 150 transit ships, 23 freighters with dangerous cargo and 2500 local transport ships with 2 million passengers on daily basis. In this study, it is aimed to create a web based GIS application for an effective coast management which includes berthing factors (anchorage areas, currents, submerged, etc.), maritime traffic factors (traffic separation schemes, traffic flow directions), closed areas and other factors (lighthouses, buoys, beacons, etc.) by digitizing printed navigation charts produced by Turkish Naval Forces, Office of Navigation, Hydrography and Oceanography.


Bakirman T.,YTU | Gumusay M.U.,YTU | Tuney I.,Ege University
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2016

Benthic habitat is defined as ecological environment where marine animals, plants and other organisms live in. Benthic habitat mapping is defined as plotting the distribution and extent of habitats to create a map with complete coverage of the seabed showing distinct boundaries separating adjacent habitats or the use of spatially continuous environmental data sets to represent and predict biological patterns on the seafloor. Seagrass is an essential endemic marine species that prevents coast erosion and regulates carbon dioxide absorption in both undersea and atmosphere. Fishing, mining, pollution and other human activities cause serious damage to seabed ecosystems and reduce benthic biodiversity. According to the latest studies, only 5-10% of the seafloor is mapped, therefore it is not possible to manage resources effectively, protect ecologically important areas. In this study, it is aimed to map seagrass cover using Landsat 8 OLI images in the northern part of Mediterranean coast of Turkey. After pre-processing (e.g. radiometric, atmospheric, water depth correction) of Landsat images, coverage maps are produced with supervised classification using in-situ data which are underwater photos and videos. Result maps and accuracy assessment are presented and discussed.


Yastikli N.,YTU | Cetin Z.,YTU
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2016

LiDAR is one of the most effective systems for 3 dimensional (3D) data collection in wide areas. Nowadays, airborne LiDAR data is used frequently in various applications such as object extraction, 3D modelling, change detection and revision of maps with increasing point density and accuracy. The classification of the LiDAR points is the first step of LiDAR data processing chain and should be handled in proper way since the 3D city modelling, building extraction, DEM generation, etc. applications directly use the classified point clouds. The different classification methods can be seen in recent researches and most of researches work with the gridded LiDAR point cloud. In grid based data processing of the LiDAR data, the characteristic point loss in the LiDAR point cloud especially vegetation and buildings or losing height accuracy during the interpolation stage are inevitable. In this case, the possible solution is the use of the raw point cloud data for classification to avoid data and accuracy loss in gridding process. In this study, the point based classification possibilities of the LiDAR point cloud is investigated to obtain more accurate classes. The automatic point based approaches, which are based on hierarchical rules, have been proposed to achieve ground, building and vegetation classes using the raw LiDAR point cloud data. In proposed approaches, every single LiDAR point is analyzed according to their features such as height, multi-return, etc.Then automatically assigned to the class which they belong to. The use of un-gridded point cloud in proposed point based classification process helped the determination of more realistic rule sets. The detailed parameter analyses have been performed to obtain the most appropriate parameters in the rule sets to achieve accurate classes. The hierarchical rule sets were created for proposed Approach 1 (using selected spatial-based and echo-based features) and Approach 2 (using only selected spatial-based features) and have been tested in the study area in Zekeriyaköy, Istanbul which includes the partly open areas, forest areas and many types of the buildings. The data set used in this research obtained from Istanbul Metropolitan Municipality which was collected with 'Riegl LSM-Q680i' full-waveform laser scanner with the density of 16 points/m2. The proposed automatic point based Approach 1 and Approach 2 classifications successfully produced the ground, building and vegetation classes which were very similar although different features were used.


Bakirman T.,YTU
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2012

In this paper, it is aimed to create a visual tour based on panoramic images for Civil Engineering Faculty in Yildiz Technical University. For this purpose, panoramic images should be obtained. Thus, photos taken with a tripod to have the same angle of view in every photo and panoramic images were created with stitching photos. Two different cameras with different focal length were used. With the panoramic images, visual tour with navigation tools created.


Sahin I.,General Command of Mapping | Alkis Z.,YTU
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2013

Increase in the number of satellites and the utilization of digital cameras in the aerial photography has spread the use of satellite image and oriented aerial photograph as real or near-real time resolution, accessible, cost effective spatial data. Co-registered images or aerial photos corrected for the height variations and orthogonality (scale) have become an essential input for geographical information systems and spatial decision making due to their integration with the other spatial data. Beyond that, images and photographs compose infrastructure for the other information in usage of spatial data with the help of the access and query facility web providing. Although the issue of the aerial photo ortho-rectification has been solved long ago, the problems related with the storage of huge amount of photos and images, their management, processes, and user accesses have been raised. These subjects concern the multitudinous private and governmental institutes. Some governmental organizations and private companies have gained the technical ability to perform these works in recent times. This situation has lead to significant increase in the amount of aerial photograph taking and processing in one year for whole country. General Command of Mapping has been using digital aerial camera since 2008 for the photograph taking. The total area covered by the satellite images, purchased for different purposes, and the aerial photographs, taken for some revision purposes or demands of governmental and private institutes, has reached up to 200.000 km2. It is considered that, colored and high resolution orthophotos of the whole country can be achieved within four years; provided that the annual production would continue similarly without any increase in amount. From the numbers given above, it is clear and inevitable that the orthophoto production procedure must be improved in order to produce orthophotos in the same year just after the photograph takings. Necessary studies about the storage, management and presentation of the huge amounts of orthophoto images to the users must be started immediately. In this study; metadata components of the produced orthophotos compatible with the international standards have been defined, a relational database has been created to keep complete and accurate metadata, and a user interface has been developed to insert the metadata into the database. Through the developed software, some extra time has been saved while creating and querying the metadata.


Yastikli N.,YTU | Bagci I.,YTU | Beser C.,YTU
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2013

The collection and updating of 3D data is the one of the important steps for GIS applications which require fast and efficient data collection methods. The photogrammetry has been used for many years as a data collection method for GIS application in larger areas. The Unmanned Aerial Vehicles (UAV) Systems gained increasing attraction in geosciences for cost effective data capture and updating at high spatial and temporal resolution during the last years. These autonomously flying UAV systems are usually equipped with different sensors such as GPS receiver, microcomputers, gyroscopes and miniaturized sensor systems for navigation, positioning, and mapping purposes. The UAV systems can be used for data collection for digital elevation model DEM and ortho-images generation in GIS application at small areas. In this study, data collection and processing by light UAV system will be evaluated for GIS data capture and updating for small areas where not feasible for traditional photogrammetry. The main aim of this study is to design the low cost light UAV system for GIS data capture and update. The investigation was based on the aerial images which recorded during the flights performed with UAV system over the test site in Davutpasa Campus of Yildiz Technical University, Istanbul. The quality of generated DEM and ortho-images from UAV flights was discussed for GIS data capture and updating for small areas.


Yastikli N.,YTU | Guler E.,YTU
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2013

The aim of this research is the performance evaluation of the termographic cameras for possible use for photogrammetric documentation and deformation analyses caused by moisture and isolation problem of the historical and cultural heritage. To perform geometric calibration of the termographic camera, the 3D test object was designed with 77 control points which were distributed in different depths. For performance evaluation, Flir A320 termographic camera with 320×240 pixels and lens with 18 mm focal length was used. The Nikon D3X SLR digital camera with 6048 × 4032 pixels and lens with 20 mm focal length was used as reference for comparison. The size of pixel was 25 μm for the Flir A320 termographic camera and 6 μm for the Nikon D3X SLR digital camera. The digital images of the 3D test object were recorded with the Flir A320 termographic camera and Nikon D3X SLR digital camera and the image coordinate of the control points in the images were measured. The geometric calibration parameters, including the focal length, position of principal points, radial and tangential distortions were determined with introduced additional parameters in bundle block adjustments. The measurement of image coordinates and bundle block adjustments with additional parameters were performed using the PHIDIAS digital photogrammetric system. The bundle block adjustment was repeated with determined calibration parameter for both Flir A320 termographic camera and Nikon D3X SLR digital camera. The obtained standard deviation of measured image coordinates was 9.6 μm and 10.5 μm for Flir A320 termographic camera and 8.3 μm and 7.7 μm for Nikon D3X SLR digital camera. The obtained standard deviation of measured image points in Flir A320 termographic camera images almost same accuracy level with digital camera in comparison with 4 times bigger pixel size. The obtained results from this research, the interior geometry of the termographic cameras and lens distortion was modelled efficiently with proposed approach for geometric calibration.


Yastikli N.,YTU | Uzar M.,YTU
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2013

In this study, the automatic building extraction is aimed using object-based image analysis method with multi sensor system includes LiDAR, digital camera and GPS/IMU. The image processing techniques, segmentation and classification methods were used for automatic object extraction with defined rule set. The proposed method based on object based classification to overcome the limitation of traditional pixel based classification such as confusion of classes. The generated Digital Surface Model (DSM) from LiDAR point cloud was used to separate building and vegetation classes. The morphologic filters were utilized also optimization of mixed classes. In our proposed approach for building extraction, multi-resolution, contrast-difference and chessboard segmentations were applied. The object-based classification method was preferred in classification process with defined fuzzy rules. First, vegetation and ground classes were generated than building regions were derived with using the results of the classification and segmentation. The data set was obtained from the project of "NABUCCO Gas Pipeline Project". The data set actually was collected for corridor mapping of pipeline which will link the Eastern border of Turkey, to Baumgarten in Austria via Bulgaria, Romania and Hungary. The study area is a suburban neighborhood located in the city of Sivas, Turkey. The Leica ALS60 LiDAR system, DiMAC, Dalsa Area Bayer RGB Charge Coupled (CCD) Camera and GPS and CUS6 IMU system were used for data collection. The additional data sets were generated with point cloud collected by LiDAR and RGB images from digital camera. The rule sets for automatic building extraction were developed in Definiens e-Cognition Developer 8.64 program system. To evaluate the performance of proposed automatic building extraction approach, reference data set was generated with digitizing of extracted building over the orthoimage. The accuracy assessment was performed with completeness and correctness analyses. Based on the completeness and accuracy analysis, the success rates of 83.08% for completeness and 85.51% for correctness were achieved.


Korkmaz F.C.,YTU | Guzel B.,YTU | Safa A.,YTU
Proceedings of the International Offshore and Polar Engineering Conference | Year: 2016

In this work, the effect of hydrophobicity has been studied experimentally on bow flare slamming and wet deck slamming by conducting water entry tests with a scaled ship section having bulbous bow and with a scaled catamaran section, respectively. The drop tests were performed from various heights with uncoated and hydrophobic coated models. The differences in jet flows, water pileups and water splashes were demonstrated by comparing high speed camera images obtained for both cases. The pileup coefficient and splash velocity have been calculated via camera images for four different drop heights in each case. The impact loads acting on the surface of the bodies have been measured by applying strain gage measurements and then compared between uncoated and hydrophobic coated surfaces for both models. Results showed that the application of hydrophobic coating on surface reduced the impact effect on bodies as a result of transferring more kinetic energy into the water. © Copyright 2016 by the International Society of Offshore and Polar Engineers (ISOPE).

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