刘万军,张壮,姜文涛,张晟翀(辽宁工程技术大学软件学院, 葫芦岛 125105;辽宁工程技术大学研究生院, 葫芦岛 125105;光电信息控制和安全技术重点实验室, 天津 300308)
目的 复杂环境下，运动目标在跟踪过程中受尺度变换以及遮挡因素的影响，跟踪准确率较低。针对这一问题，提出一种遮挡判别下的多尺度相关滤波跟踪方法。方法 首先选取第1帧图像的前景区域，训练目标的位置、尺度滤波器和GMS（grid-based motion statistics）检测器。然后，通过位置滤波器估计目标位置，尺度滤波器计算目标尺度，得到初选目标区域。最后，利用相关滤波响应情况对初选目标区域进行评估，通过相关滤波响应值的峰值和峰值波动情况判断是否满足遮挡和更新条件。若遮挡，启动检测器检测目标位置，检测到目标位置后，更新目标模型；若更新，则更新位置、尺度滤波器和GMS检测器，完成跟踪。结果 本文使用多尺度相关滤波方法作为算法的基本框架，对尺度变化目标跟踪具有较好的适应性。同时，利用目标模型更新机制和GMS检测器检索目标，有效地解决了遮挡情况下的目标丢失问题。在公开数据集上的测试结果表明，本文算法平均中心误差为5.58，平均跟踪准确率为94.2%，跟踪速度平均可达27.5 帧/s，与当前先进的跟踪算法相比，本文算法兼顾了跟踪速度和准确率，表现出更好的跟踪效果。结论 本文提出一种新的遮挡判别下的多尺度相关滤波跟踪算法。实验结果表明，本文算法在不同的尺度变换及遮挡条件下能够快速准确跟踪目标，具有较好的跟踪准确率和鲁棒性。
Multi-scale correlation filter tracking algorithm based on occlusion discrimination
Liu Wanjun,Zhang Zhuang,Jiang Wentao,Zhang Shengchong(School of Software, Liaoning Technical University, Huludao 125105, China;Graduate School, Liaoning Technical University, Huludao 125105, China;Science and Technology on Electro-Optical Information Security Control Laboratory, Tianjin 300308, China)
Objective Visual target tracking has become a popular research topic locally and globally in the field of artificial intelligence, which is widely used in national defense security, industry, and people's daily life, such as military recognition, security monitoring, pilotless automobile, and human-computer interaction. Although great progress has been realized in the past decade, model-free tracking remains a tough problem due to illumination changes, geometric deformation, partial occlusion, fast motions, and background clutters. The traditional methods of target tracking generally track the target through visual features. In the case of the simple environment, these trackers can perform well for specific targets. Recently, visual object tracking has been widely applied to object tracking field due to its efficiency and robustness of correlation filter theory. A series of new advances of target tracking have been introduced and much attention has been achieved. A novel approach to predictive tracking, which is based on occlusion discriminant multi-scale correlation filter tracking algorithm, is proposed to overcome the problems of low accuracy caused by occlusion, which are scale changes in the tracking processin complex environments. Method On the basis of the basic framework of DSST (discriminated scale space tracker), a multi-scale correlation filter tracking algorithm is proposed. Reliability discrimination for the results of the correlation filter response, which contributes to long-term stable tracking, refers to occlusion and update discrimination by the peak and multiple peak fluctuation of the response map. The proposed algorithm in this paper can be summarized as two main points:1) Two types of calculation models were designed for the maximum and multiple peak fluctuation. By evaluating the tracking results according to the two abovementioned models, we can determine the occlusion of the target, and whether the target should be updated. 2) Redetect the missing target using the detector based on GMS (grid-based motion statistics). When the target is occluded, the GMS detector has been trained start to detect the target and locate it again. Concrete tracking is conducted as follows:First, the foreground area of the first frame image is selected, and the target position and scale filters and GMS detector are trained. Then, the target location is estimated by the translation filter, and the target scale is calculated by the scale filter. Performing a correlation between the candidate samples that are obtained using different scales center on the new position, and the scale correlation filter derives the primary target area. The maximum response scale is the current frame image scale. Finally, the primary target area is evaluated by the correlation filter response, and occlusion and update conditions are determined by the peak and multiple peak fluctuation of the correlation filter response values. The mutation of the peak and multiple peak fluctuation indicated that the target is occluded at the moment. The greater the mutation, the greater the degree of occlusion. In this case, update should be avoided to prevent tracking drift. If the target is occluded, then the detector detects the target position and updates the target model after detecting the target location. When the peak value of the correlation filter response is greater than the historical value, and the peak fluctuation does not mutate, then the target information at the moment is complete than that at time t-1, and the correlation filter should be updated. If the target is updated, then this update should focus on the location and scale filters and the GMS detector to complete tracking. Result The multi-scale correlation filtering method is used as the basic framework in our algorithm, which displays good adaptability to the target tracking of scale transformation. At the same time, the target model updating mechanism and GMS detector are used to retrieve the target and effectively solve the target loss problem in the occlusion. This paper selected nine challenging video sequences namely, Box, Bird1, Lemming, Panda, Basketball, DragonBaby, CarScale, Bird2, Girl2 from the public dataset OTB-2013 and OTB-2015, and video data car_Xvid, to conduct the experiments. The test results from using the public datasets show that the algorithm has a lower average center error of 5.58 and has a better tracking accuracy of 0.942 and tracking speed of 27.5 frames per second, compared with state-of-the-art tracking algorithms DSST, KCF (kernel correlation filter), LCT (long-term correlation tracking), Staple, GOTUTN (generic object tracking by using regression networks), and FCNT (fully convolutional networks tracking). Thus, the algorithm shows improved tracking performance with higher tracking speed and accuracy. Conclusion Based on DSST correlation filtering tracking, a multi-scale correlation filtering method based on occlusion discrimination is proposed. The results show that the algorithm solved the problems of losing goals due to occlusion and error accumulation because of the continuously and effectively updated strategy and achieved stable tracking under occlusion and multi-scale changes. Compared with current popular tracking algorithms, this algorithm has the following remarkable advantages:Solves the problem of losing goals due to occlusion in DSST algorithm and detects occlusion and determines whether updates can mitigate the tracking drift problem via frame update. Doing so can not only reduce unnecessary update time, but also substantially improve the tracking speed and accuracy. This paper presents a new multi-scale correlation filtering tracking algorithm based on occlusion discrimination. Experiments show that the proposed algorithm can track the target rapidly and accurately under conditions of varying scale transformation and occlusion, and it has enhanced tracking accuracy and robustness.