Ferruh Yilmazturk

Unmanned Aerial Vehicles (UAVs), can be controlled automatically or with the help of a remote control system, provide high spatial and temporal resolution images in addition to its advantages in terms of cost and time. Due to these features, UAV’s have been widely used in studies such as map production, 3D modeling and volume calculation in recent years. In this study, it is aimed to investigate the effects of different flight parameters on the accuracy of Orthomosaic and DEM produced with UAV Systems. In addition, the rolling shutter effect and the use of pre-calibrated and automatic camera calibration parameters were also tested. For this purpose, a total of seven UAV flights were carried out at different heights, overlap ratios, angles and grids at a mining area located within the borders of Aksaray province. Agisoft MetaShape and Pix4D Mapper, which are widely used commercial software, were used to process the UAV images. In this study, 27 points were established and 3D coordinates of these points were measured using GNSS technique. 15 of these points were used as reference points and the remaining 12 points were used as check points. Accuracy analysis was performed by comparing the produced Orthomosaics and DEMs with the check points in the study area. CloudCompare and ArcGIS software were used in the comparison of the products as a result of the evaluation of the images. It is concluded that the Orthomosaics produced using 450 angle and DEMs with 600 angle has higher accuracy than the others. Point clouds and DEMs’ produced using automatic and pre-calibrated camera calibration parameters show that the pre-calibrated images provide higher accuracy. Also, it is seen that when the rolling shutter effect is modeled, the horizontal and vertical accuracy is increased in all three flights with different flight parameters in this study.

This study aimed to investigate the usability of smartphone camera images in 3D positioning applications with photogrammetric techniques. These investigations were performed in two stages. In the first stage, the cameras of five smartphones and a digital compact camera were calibrated using a calibration reference object, with signalized points having known three-dimensional (3D) coordinates. In the calibration process, the self-calibration bundle adjustment method was used. To evaluate the metric performances, the geometric accuracy tests in the image and object spaces were performed and the test results were compared. In the second stage, a 3D mesh model of a historical cylindrical structure (height = 8 m and diameter = 5 m) was generated using Structure-from-Motion and Multi-View-Stereo (SfM-MVS) approach. The images were captured using the Galaxy S4 smartphone camera, which produced the best result in the geometric accuracy tests for smartphone cameras. The accuracy tests on the generated 3D model were also applied in order to examine 3D object reconstruction capabilities of imaging with this device. The results demonstrated that smartphone cameras can be easily used as image acquisition tools for multiple photogrammetric applications.

Bu çalışmada, statik yada yarı statik yükleme deneylerinde yapı elemanlarının deformasyon davranışlarını gerçek zamana yakın (<1 sn) belirleyebilmek için geliştirilen fotogrametrik bir sistem anlatılmıştır. Sistem yazılım ve donanım olmak üzere iki bileşenden oluşmaktadır. Donanım bileşeni 3 video kameralı görüntü elde etme sistemini, yazılım bileşeni de elde edilen görüntülerin fotogrametrik olarak değerlendirilip konum bilgisinin üretilmesini içerir. Sistemin ölçme işlemi, üç kameraya ait iç ve dış yöneltme parametrelerinin belirlendiği sistem kalibrasyonu ve sonra bu kalibrasyon parametreleri yardımıyla, tanımlanabilen zaman aralıklarında ya da her bir yükleme uygulamasından sonra yapı elemanı üzerindeki işaretli noktaların 3B koordinatlarının hesaplanması ilkesine dayanır. Test amacıyla, sistem gömülü esnek boruların ve çelik bir kirişin yük testi deneylerinde kullanılmıştır. Deneylerde inşaat mühendisliği klasik ölçme aletleri de kullanılmış ve her iki ölçme sisteminden elde edilen sonuçların kıyaslaması, fotogrametrik sistemin doğru ve güvenilir bir ölçme sistemi olduğunu göstermiştir.