Elamin Ahmed, El-Rabbany Ahmed
Department of Civil Engineering, Toronto Metropolitan University, Toronto, ON M5B 2K3, Canada.
Department of Civil Engineering, Faculty of Engineering, Zagazig University, Zagazig 44519, Egypt.
Sensors (Basel). 2023 Nov 21;23(23):9315. doi: 10.3390/s23239315.
Pavement surface maintenance is pivotal for road safety. There exist a number of manual, time-consuming methods to examine pavement conditions and spot distresses. More recently, alternative pavement monitoring methods have been developed, which take advantage of unmanned aerial systems (UASs). However, existing UAS-based approaches make use of either image or LiDAR data, which do not allow for exploring the complementary characteristics of the two systems. This study explores the feasibility of fusing UAS-based imaging and low-cost LiDAR data to enhance pavement crack segmentation using a deep convolutional neural network (DCNN) model. Three datasets are collected using two different UASs at varying flight heights, and two types of pavement distress are investigated, namely cracks and sealed cracks. Four different imaging/LiDAR fusing combinations are created, namely RGB, RGB + intensity, RGB + elevation, and RGB + intensity + elevation. A modified U-net with residual blocks inspired by ResNet was adopted for enhanced pavement crack segmentation. Comparative analyses were conducted against state-of-the-art networks, namely U-net and FPHBN networks, demonstrating the superiority of the developed DCNN in terms of accuracy and generalizability. Using the RGB case of the first dataset, the obtained precision, recall, and F-measure are 77.48%, 87.66%, and 82.26%, respectively. The fusion of the geometric information from the elevation layer with RGB images led to a 2% increase in recall. Fusing the intensity layer with the RGB images yielded a reduction of approximately 2%, 8%, and 5% in the precision, recall, and F-measure. This is attributed to the low spatial resolution and high point cloud noise of the used LiDAR sensor. The second dataset crack samples obtained largely similar results to those of the first dataset. In the third dataset, capturing higher-resolution LiDAR data at a lower altitude led to improved recall, indicating finer crack detail detection. This fusion, however, led to a decrease in precision due to point cloud noise, which caused misclassifications. In contrast, for the sealed crack, the addition of LiDAR data improved the sealed crack segmentation by about 4% and 7% in the second and third datasets, respectively, compared to the RGB cases.
路面表面维护对道路安全至关重要。存在许多人工且耗时的方法来检查路面状况并发现病害。最近,已开发出替代的路面监测方法,这些方法利用了无人机系统(UAS)。然而,现有的基于UAS的方法要么使用图像数据,要么使用激光雷达数据,无法利用这两种系统的互补特性。本研究探讨了融合基于UAS的成像数据和低成本激光雷达数据以使用深度卷积神经网络(DCNN)模型增强路面裂缝分割的可行性。使用两种不同的UAS在不同飞行高度收集了三个数据集,并研究了两种类型的路面病害,即裂缝和密封裂缝。创建了四种不同的成像/激光雷达融合组合,即RGB、RGB + 强度、RGB + 高程以及RGB + 强度 + 高程。采用了受ResNet启发带有残差块的改进U-net用于增强路面裂缝分割。针对最先进的网络,即U-net和FPHBN网络进行了对比分析,证明了所开发的DCNN在准确性和通用性方面的优越性。使用第一个数据集的RGB情况,得到的精度、召回率和F值分别为77.48%、87.66%和82.26%。高程层的几何信息与RGB图像的融合使召回率提高了2%。强度层与RGB图像的融合使精度、召回率和F值分别降低了约2%、8%和5%。这归因于所用激光雷达传感器的低空间分辨率和高激光点云噪声。第二个数据集的裂缝样本获得了与第一个数据集大致相似的结果。在第三个数据集中,在较低高度捕获更高分辨率的激光雷达数据导致召回率提高,表明裂缝细节检测更精细。然而,这种融合由于激光点云噪声导致精度下降,从而引起误分类。相比之下,对于密封裂缝,与RGB情况相比,在第二个和第三个数据集中添加激光雷达数据分别使密封裂缝分割提高了约4%和7%。