Infrared imaging has been widely used in the field of sea surface monitoring. Horizon detection is a key step before a target’s detection, locating, and tracking in the sea–sky infrared scene. Reducing processing time while ensuring accuracy is the research focus of infrared horizon detection. This paper proposes a novel method of a line segment detector (LSD) algorithm with gradient direction filtering. First, the rough extraction of the sea–sky region is used to limit the size of the detected image, and then the potential horizon line segment is extracted, applying the improved LSD algorithm in the sea–sky region, which probably contains many false extraction results. Then, gradient direction filtering is designed to pick the horizon line segments in this step. Finally, the horizon line segments are stitched to obtain the whole horizon line based on random sample consensus. The results of the comparative experiments show that this novel method has high detection accuracy, and the processing time is significantly shortened; what is more, we can also conclude that this method has a good performance on the detection stability.

中文翻译：

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基于梯度定向滤波的快速红外层位检测算法

红外成像已被广泛用于海面监测领域。地平线检测是在海天红外场景中对目标进行检测，定位和跟踪之前的关键步骤。在确保精度的同时减少处理时间是红外水平检测的研究重点。提出了一种具有梯度方向滤波的线段检测器（LSD）算法。首先，使用海天区域的粗略提取来限制所检测图像的大小，然后在海天区域中应用改进的LSD算法提取潜在的地平线线段，其中可能包含许多错误提取结果。然后，在此步骤中，将梯度方向滤波设计为选择地平线线段。最后，根据随机样本共识，将视线段进行缝合以获得整个视线。对比实验结果表明，该新方法检测精度高，处理时间明显缩短。此外，我们还可以得出结论，该方法具有良好的检测稳定性。