Citation: | Cao C L, Tao C B, Li H Y, et al. Deep contour fragment matching algorithm for real-time instance segmentation[J]. Opto-Electron Eng, 2021, 48(11): 210245. doi: 10.12086/oee.2021.210245 |
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Overview: With the help of instance segmentation, the scene information can be better understood, and the perception system of autonomous driving can be effectively improved. However, due to the problems such as object occlusion and object blur during detection, the accuracy of instance segmentation is greatly reduced. Deep neural network is a common method to solve object occlusion and blur. Based on computing resources and real-time considerations, contour-based algorithms are other solutions. Active Contour Model (ACM) is a classic contour algorithm, which is called Snake model. Its parameters are less than those based on dense pixels, which speeds up the segmentation. A novel segmentation algorithm based on ACM combined with cyclic convolution is proposed. The algorithm uses center net as the target detector to update the vertices using the iterative calculation of cyclic convolution and vertex offset calculation, and finally fits the real shape of the body. The algorithm has three main contributions. Firstly, for object occlusion and blurring, a loss function (target aggregation loss) is introduced, which increases the positioning accuracy of the detection box by pulling and repelling surrounding objects to the target. Secondly, the initial contour processing is an important step based on the contour algorithm, which affects the accuracy and speed of subsequent instance segmentation. This paper proposes a method of processing the initial contour, which is fragment matching. The initial contour to be processed is caused by evenly spaced points. The detection box is adaptively divided into multiple segments. The segments correspond to the initial contour. Each segment is matched point by point and assigned vertices. These vertices are the key to subsequent deformation. Finally, in dense scenes, it is easy to lose the information of adjacent objects in the same detection box. This paper proposes a boundary coefficient module to correct the misjudged boundary information by dividing the area and aligning the features to ensure the accuracy of boundary segmentation. The algorithm in this paper is compared with multiple advanced algorithms in multiple data sets. In the Cityscapes dataset, an APvol of 37.7% and an AP result of 31.8% are obtained, which is an improvement of 1.2% APvol compared to PANet. In SBD dataset, the results of 62.1% AP50 and 48.5% AP70 were obtained, indicating that even if the IoU threshold changes, the AP does not change much, which proves its stability. Compared with other real-time algorithms in the COCO dataset, a trade-off between accuracy and speed was achieved, reaching 33.1 f/s, while the COCO test-dev has 30.7% mAP. After the above data analysis, it is proved that the algorithm in this paper has reached a good level in accuracy and speed.
DCFM deformation pipeline
Detection process of CenterNet
Advantages of fragment matching
Iterative deformation process
Iterative deformation process
The renderings of Cityscapes and Kins
(a) The speed and real-time performance of each state-of-the-art in COCO; (b) PR curve comparison
The segmentation effect of SBD and COCO
Common scene splitting effect in real life
Ablation experiment of the number of missed detections