heal.abstract |
The present thesis is an attempt to light a spark in the field of object detection in ship navigation. This introduction is followed by an application based on an object detection model, named You Only Look Once (YOLO). Even though it is not the first time an object detection algorithm was applied to ship navigation problems, it is very fascinating to further research and experiment in this field by firstly testing an already existing algorithm and commenting on the results.
Many object detection algorithms have been proposed with approaches ranging from traditional to deep learning. However, the majority of them have limited applications in real-time applications as they are computationally intensive and have accuracy problems. Another challenge when dealing with ship navigation is the wide range of background sizes of the objects. To overcome these problems the most recent object detection algorithm was selected. In this thesis, the You Only Look Once version 5 (YOLOv5) model was used, which is created in 2020 and is fine-tuned with the more recent and best practices in object detection and also is constantly modified and readjusted to achieve better results. From the different models of YOLOv5, the smaller one was picked, because of its size and the comparatively good accuracy it performs.
After the model was chosen, a sufficient database for the model’s training was created using images that contained the most common obstacles that a ship can face. These are other ships, buoys, humans on the surface, containers, and rocks. The images were categorized into 3 teams, ship, floating object, and rock, which are the classes of the problem. The images were then labeled in a way that the YOLO accepts as input while some of them were kept and created the validation dataset. With these data some scenarios were created, namely, images that contained only one class in them, images of ship at night, and images of at least 2 classes coexisting in the same image and their combination. The model was trained with these different datasets and the results were collected, compared, and analyzed. The model achieved a Precision of 84%, Recall of 74%, and mAP of 79% on average when trained with 400 images of all the classes combined for 300 epochs and batch size 8. The model was also tested in a real-time application using a video and it detected all of the ships in most cases with 33 frames per second reload time. |
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