An analysis of the production state of a construction project with the unmanned aerial vehicle photogrammetry application

Since humanity ever existed, the relation between soil and water has been an important part of our lives. There has also been a need for measuring in order to establish a basis for determining, dividing, rearranging existing land borders and water-saving areas as well as studies near such areas, and this need has paved the way for the emergence of maps. As technology advances, measuring systems have simultaneously been developed and by integrating them into electronic devices, it has been attempted to save money, equipment and most importantly, time. Aside from local measurement systems, great developments have been achieved in the field of remote sensing and photogrammetric mapping. By evaluating aerial and satellite images using appropriate software during automation process, topographic and thematic mapping on different scales can be achieved. Using advanced computer software, these measurements have been evaluated to test their accuracy and thanks to these data, engineers have come up with maps which are almost as accurate as local measurement systems. Photogrammetry is a field of art which is used in many different disciplines and changes as technology advances. On account of the fact that it is used in various disciplines, photogrammetry is divided into categories such as the number of images which are used in the analysis process, the analysis method, the location where the image is taken, the magnitude of the object and the discipline. Depending on the location where the image is taken, photogrammetry has two categories; terrestrial and aerial photogrammetry. Terrestrial photogrammetry is a technique which is applied on the earth and around the earth. Aerial photogrammetry, on the other hand, is a mapping technique that is used in order to take high-altitude images, where it is not possible to reach by terrestrial methods so that it enables engineers to map wide landscapes with ease. In other words, terrestrial photogrammetry is preferred only when aerial photogrammetry is not used because it is too hard to take images, analyze images and gather information about wide landscapes by means of it and when it is not economic or special matters are taken into account. Depending on the number of images used during the analysis, photogrammetry is broken into two branches which are single and double-image photogrammetry. Single-image photogrammetry is a technique by which image plans and image mosaics are designed. Double-image photogrammetry, also known as stereo photogrammetry, is a technique by which three-dimensional information is gathered by means of image pairs where there are common coverage areas. Based on the analysis method, photogrammetry consists of four methods. Graphical photogrammetry is an analysis method which is used for direction and length measurements and perspective map production. Analog photogrammetry is a method by which three-dimensional models of images that are taken by using double-image photogrammetry are created and by which objects are analyzed by means of schematic techniques. Analytical photogrammetry is a method in which electronic and computer systems are utilized in addition to mathematical methods and analog photogrammetry. Finally, digital photogrammetry is a method in which stereo images, which are converted into digital forms, are automatically analyzed via computer software. Of all the methods mentioned above, the aerial photogrammetry method yields results by making use of stereo photogrammetry and digital photogrammetry methods. In this thesis study, a point cloud has been developed so as to analyze the photographs taken with the help of Unmanned Aerial Vehicles (UAVs), their integration with the topography and evaluation, magnitude calculation, production controls and ortophotos have been produced to create a basis for digital surface models and provide visual support for the project. In this thesis study, as a result of the analysis of the photographs taken with the help of drones, their integration with the topography and evaluation, a point cloud for product controls; a digital surface model for volume and other mathematical calculations; ortophotos for visual reference for the project have been developed. In the scope of this study, an ongoing railway project in Ethiopia, which is one of the fastest developing economies in the African continent, has been made use of. This is a 392-km railway project, which is going on along the Awash-Kombolcha-Hara Gebaya line. This railway line consists of two phases. In the first phase, in order to render the cut-fill and construction fields within a range of KM 0+000 – KM 270+500 area controllable, photogrammetric studies have been conducted. In the application part of the thesis, because of the excessive number of photos and the data size of these photos, some parts of the photogrammetric studies, which were done in the AKH project, have been utilized. The application part consists of three parts. In the first part of the application, the GPS data, which were acquired through real-time kinematic measurements, have been integrated into the raw photos. Additionally, thanks to these GPS data, the photos have been stabilized. In the final part of the section, by marking the GCPs, the photos have been placed on the topography. In the second part of the application, on the data that were acquired through the editing in the first part, aerial triangulation and balancing as well as quality-control processes have been done. During the aerial triangulation studies, three different methods have been used in order to find out the best result. These three methods include only the RTK GPS data, only ground control points, and the utilization of all the RTK GPS data and ground control points for stabilization. The main purpose of these methods is to ensure the stabilization of the photos and to control the harmony between both the RTK GPS data and ground control points and each other. As a result of all these steps, by combining the photos, one single surface has been created. Finally, through this surface, a point cloud, a digital surface model and ortophotos have been developed. In the final part of the application, the report, which was about the photogrammetric study that was conducted, has been compared with the report that was filed where the field study was done. This comparison has been done with volume calculations. In addition, the surface model, which was designed at the beginning of the AKH project by making use of photogrammetric methods, has been utilized in calculations for checking. It is believed that the methods, which were used and the results that were encountered in this study, will provide a theoretical background and contribute to the worldwide photogrammetric studies concerning constructional projects.