A novel lightweight bilateral segmentation network for detecting oil spills on the sea surface

SGDBNet: A scene-class guided dual branch network for port UAV images oil spill detection

The unmanned aerial vehicle (UAV) is usually flexible and frequently low-altitude flying without the influence of clouds and severe weather, and it is widely used for port oil spill detection (OSD). However, the background of the port is usually complex, the oil spills in UAV images are usually small and irregular, as well as the oil boundary is fuzzy, which has led to the failure of existing methods in accurately detecting the port oil spill. Here, we propose a scene-class guided dual branch network for port OSD based on UAV images, which can locate the oil spill areas of different sizes and suppress the influence caused by complex backgrounds. Specifically, the dual-branch network consists of semantic segmentation and image classification branches. The image classification branch utilizes the scene-class as the label and further can extract the feature attention, which can guide the semantic segmentation branch to learn the key area features. Second, we propose a multi-scale arbitrary shape convolution module, which can address the challenges caused by fuzzy oil boundaries and irregular small objects. Finally, due to the imbalance between oil spill pixels and other pixels, we design a joint loss to optimize the network. We evaluate our proposed method on a public UAV OSD dataset. The results show that our method is superior to the state-of-the-art method, achieving mIoU of 90.22 %, A of 96.03 %, P of 91.99 %, R of 92.56 %, and F1 of 92.28 %, which represents the feasibility of our method in port OSD and its potential to save a lot of manpower and material resources. The ablation experiment further demonstrates the effectiveness of each designed part.

Marine oil spill detection and segmentation in SAR data with two steps Deep Learning framework

Marine oil spills pose significant ecological and economic threats worldwide, requiring effective decision-making tools. In this study, the optimal parameters, and configurations for Deep Learning models in oil spill classification and segmentation using Sentinel-1 SAR imagery were identified. First, a new Sentinel-1 image dataset was created. Ninety CNN configurations were explored for classification by varying the number of convolutional layers, filters, hidden layers, and neurons in each layer. For segmentation tasks, MLP and U-Net models were evaluated with variations in convolutional layers, filters, and incorporation of IoU and Focal Loss. The results indicated that a CNN model with six layers, 32 filters, and two hidden layers achieved 99 % classification accuracy. For segmentation, the U-Net model with more layers and filters using Focal Loss achieved 99 % accuracy and 96 % IoU. Therefore, a CNN and U-Net framework was proposed that achieves an overall accuracy of 95 % and an IoU of 90 %.

A novel feature enhancement and semantic segmentation scheme for identifying low-contrast ocean oil spills

The oil spill accidents on the sea surface pose a severe threat to the marine environment and human health. This paper proposes a novel Semantic Segmentation Network (SSN) for processing oil spill images so that low-contrast oil spills on the sea surface can be accurately identified. After the detection accuracy and real-time performance of the current SSNs are compared, the basic network architecture of DeeplabV3+ based target detection is analyzed. The standard convolution is replaced by the Omni-dimensional Dynamic Convolution (ODConv) in the Ghost Module Depth-Wise separable Convolution (DWConv) to further enhance the feature extraction ability of the network. Furthermore, a new DeeplabV3+ based network with ODGhostNetV2 is constructed as the main feature extraction module, and an Adaptive Triplet Attention (ATA) module is deployed in the encoder and decoder at the same time. This not only improves the richness of semantic features but also increases the following receptive fields of the network model. ATA integrates the Adaptively Spatial Feature Fusion (ASFF) module to optimize the weight assignment problem in the feature map fusion process. The ablation experiments are conducted to verify the proposed network which show high accuracy and good real-time performance for the oil spill detection.

A novel split-frequency feature fusion framework for processing the dual-optical images of offshore oil spills

This paper presents a novel split-frequency feature fusion framework used for processing the dual-optical (infrared-visible) images of offshore oil spills. The self-coding network is used for high-frequency features of oil spill images based on local cross-stage residual dense blocks to achieve feature extraction and construct a regularized fusion strategy. The adaptive weights are designed to increase the proportion of high-frequency features in source images during the low-frequency feature fusion process. A global residual branch is established to reduce the loss of oil spill texture features. The network structure of the primary residual dense block auto-encoding network is optimized based on the local cross-stage method to further reduce the network parameters and improve the network operation speed. To verify the effectiveness of the proposed infrared-visible image fusion algorithm, the BiSeNetV2 algorithm is selected as the oil spill detection algorithm to realize the pixel accuracy of the oil spill image features at 91%.

Monitoring of oil spill in the offshore zone of the Nile Delta using Sentinel data

This study aims to monitor and map the oil spills which occurred from 2019 to 2021 along the northeastern portion of the Nile Delta using Sentinel-1 (SAR) and Sentinel-2 (MSI) data. The examination of VV polarized SAR-C images displayed the presence of the oil spills as dark spots of different sizes. These images were processed using the oil spills detection model in SNAP Toolbox. The oceanographic parameters that may influence the dispersal of oil spills were mapped using GIS technique. This study identified 29 oil spills during the study period in the research area. The largest spill was detected on February 23, 2019, and covered an area of about 10.5 km². The band ratios and decorrelation stretch methods of available Sentinel-2 data confirmed the results of SAR-C data. The accuracy assessment of spills was achieved using Parallelepiped supervised classification model. The results demonstrated that the overall accuracy (OA) and Kappa coefficient (KC) for seawater, land, and oil spills classes were between 86% and 98% and 0.73% and 0.97%, respectively. The sensitivity zone of oil spills was higher in winter than in summer. This study proved the efficiency of VV polarized data of Sentinel-1 sensor for detection and mapping of oil spills. Several management strategies are needed in the offshore zone of the Nile Delta to limit oil pollution effects on the marine environment.