基于描述符辅助光流跟踪匹配的数据关联方法

夏华佳; 章红平; 陈德忠; 李团

doi:10.3963/j.jssn.1674-4861.2021.06.018

基于描述符辅助光流跟踪匹配的数据关联方法

doi: 10.3963/j.jssn.1674-4861.2021.06.018

武汉大学卫星导航定位技术研究中心武汉 430079

基金项目:

国家重点研发计划项目 SQ2018YFE020091

长江勘测规划设计研究院开放创新基金项目 CX2020K04

详细信息

作者简介:
夏华佳(1996—), 硕士研究生. 研究方向: 视觉/INS组合导航. E-mail: 67010973@qq.com

通讯作者:
章红平(1977—), 博士, 教授. 研究方向: GNSS/INS组合导航. E-mail: hpzhang@whu.edu.cn

中图分类号: V249.32+8
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- 文章访问数: 673
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- 被引次数: 0
出版历程
- 收稿日期: 2021-07-06
- 网络出版日期: 2022-01-12

A Data Association Method Based on Tracking and Matching of Assisted Optical Flows from the Descriptor

GNSS Research Center, Wuhan University, Wuhan 430079, China

摘要

摘要: 针对采用多状态约束卡尔曼滤波(MSCKF)的视觉惯性里程计定位精度易受特征点匹配异常值影响问题, 提出了1种基于描述符辅助光流跟踪匹配的数据关联方法。该方法采用金字塔LK光流对序列图像中特征点进行跟踪匹配, 计算每一对匹配点的rBRIEF描述符, 根据Hamming距离对描述符的相似度进行判断消除异常匹配点。在实验中从特征点匹配主观效果以及定位精度2个方面评估本文方法的有效性, 结果表明: 所提出方法能够有效滤除动态场景下图像特征匹配的异常值, 使用该方法处理后的图像进行MSCKF运动解算, 位置结果漂移率小于0.38%, 相较于未剔除异常匹配值的MSCKF算法结果, 改善了54.7%, 单帧图像处理时间约为39 ms。
- 视觉惯性 /
- 数据关联方法 /
- 特征点匹配 /
- rBRIEF描述符 /
- 光流跟踪 /
- MSCKF
Abstract: The positioning accuracy of visual inertial odometer using multi-state constrained Kalman filter(MSCKF)is easily affected by mismatching points. A data association method is proposed for mitigating these outliers in this study. First, pyramid Lucas-Kanade(LK)optical flow is used to track and match the features among the sequence images. Second, the rBRIEF descriptors of each pair of matching points are achieved. Third, the Hamming distances between two rBRIEF descriptors can be calculated. Furthermore, the similarity of these descriptors is then evaluated according to Hamming distance. Last, the matching points of low similarity are eliminated as outliers in the data processing. The performances of the proposed method is assessed by the effectiveness of matching and positioning accuracy of the feature point. The results indicate that the proposed method can eliminate mismatching points in dynamic image processing. The outlier-eliminated images are applied for the MSCKF motion estimation. The derived drift rate of positioning result is less than 0.38% and shows an improvement of 54.7% with no outlier-eliminated MSCKF algorithm. The single-frame image processing time is about 39 ms.
- visual-inertial /
- data association method /
- feature matching /
- RBRIEF descriptor /
- optical flow tracking /
- MSCKF

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图 1 基于特征点的数据关联方案

Figure 1. Data association scheme based on feature points

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图 2 FAST角点检测模板

Figure 2. FAST corner detection template

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图 3 rBRIEF描述符旋转不变性

Figure 3. Rotation invariance of rBRIEF descriptor

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图 4 MSCKF视觉惯性里程计算法框图

Figure 4. MSCKF-based visual-inertial odometer algorithm

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图 5 特征点跟踪匹配点对数量图

Figure 5. Quantity of feature points tracking matching-point pairs

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图 6 载体导航状态

Figure 6. Navigation status of the carrier

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图 7 rBRIEF描述符滤除异常匹配前后对比

Figure 7. Comparison before and after rBRIEF descriptor filtering exception matching

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图 8 真值与不同算法解算轨迹图

Figure 8. Solving trajectory of the true value and different algorithms

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图 9 2种算法解算定位结果误差曲线图

Figure 9. Two algorithms solving the error curves of positioning results

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表 1 惯导设备参数

Table 1. Equipment parameters of inertial-navigation

指标	M40	POS320
陀螺零偏稳定性(℃/h)	50	0.3
角度随机游走(℃/$ \sqrt h $)	0.4	0.03
加表零偏稳定性(mGal)	200	200
速度随机游走/(m/(s/$ \sqrt h $))	0.1	0.05

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表 2 Basler acA1600-20gm相机参数

Table 2. Parameters of Basler acA1600-20gm camera

传感器类型	CCD
传感器尺寸/mm	7.16×5.44
分辨率/pixie	1628×1236
像元大小/μm	4.4×4.4
接口	千兆网
曝光控制	相机API编程控制外部脉冲信号触发
帧率/(帧/s)	20
通道数/(颜色)	单通道/(黑白)
像素位深度/bits	12

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表 3 VIO1.0解算误差统计表

Table 3. Statistics of VIO1.0 solution errors

	N/m	E/m	D/m	ROLL/(°)	PITCH/(°)	YAW/(°)
MAX	7.74	16.80	2.63	0.18	0.17	1.46
RMS	3.13	7.48	1.02	0.05	0.08	0.82

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表 4 VIO2.0解算误差统计表

Table 4. Statistics of VIO2.0 solution errors

	N/m	E/m	D/m	ROLL/(°)	PITCH/(°)	YAW/(°)
MAX	5.51	7.17	2.43	0.14	0.13	1.05
RMS	2.07	3.26	1.03	0.03	0.05	0.45

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