Improved AO Optimization Algorithm for Distortion Parameter Estimation of Catadioptric omnidirectional Lens
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摘要:
目的: 针对现有镜头畸变参数估计方法存在精度低、易陷入局部最优解的问题,提出了一种基于改进天鹰优化算法的折反射全景相机镜头畸变参数方法。方法: 首先通过融合混沌映射、自适应调节策略和通讯交流策略,增强了天鹰优化算法的寻优能力,解决了其收敛速度慢且容易陷入局部最优解的问题。其次,通过空间中直线对应的畸变边缘和单参数除法模型推导并确定畸变参数分布范围,然后构建包含畸变参数的优化目标函数。最后采用改进的天鹰优化算法对优化目标函数寻优求得最佳畸变参数。结果: 经过对标准图库图像和全景图像的校正结果分析,本文提出的方法估计的主点误差在0.5 pixel以内,径向畸变系数误差在2.5%以内,能够有效地估计镜头畸变参数并实现全景图像畸变校正。结论: 提高了视觉导航系统在环境感知任务下的图像质量,在工程应用中具有潜在价值。Abstract:ObjetiveAiming at the problems of low accuracy and easy to fall into local optimal solutions of the existing lens distortion parameter estimation methods, a catadioptric omnidirectional camera lens distortion parameter method based on the improved Aquila optimization (AO) algorithm is proposed.
MethodFirstly, the optimization ability of the Aquila optimization algorithm is enhanced by integrating chaotic mapping, adaptive adjustment strategy and population optimization strategy, which solves the problems of slow convergence speed and easy to fall into local optimal solutions. Secondly, the distribution range of distortion parameters is derived and determined by the corresponding distortion edges of straight lines in the space and the one parameter divisive model, and then the optimization objective function containing the distortion parameters is constructed. Finally, the improved Aquila optimization algorithm is used to find the best distortion parameters for the optimization objective function.
ResultAfter analyzing the correction results of standard gallery images and omnidirectional images, the method proposed in this paper estimates the main point error within 0.5 pixel and the radial aberration coefficient error within 2.5%, which is able to effectively estimate the lens aberration parameters and realize the omnidirectional image aberration correction.
ConclusionIt improves the image quality of the visual navigation system under the task of environment perception and is valuable in engineering applications.
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表 1 参数设定
Table 1. Parameter settings
表 2 基准测试函数
Table 2. Benchmark function
函数序号 函数名称 维度 范围 最优值 F1 Sphere 30 [−100,100] 0 F2 Schwefel 2.22 30 [−10,10] 0 F3 Schwefel 1.2 30 [−100,100] 0 F4 Schwefel 2.21 30 [−100,100] 0 F5 Ackley 10 [−32,32] 0 F6 Generalized Penalized 30 [−50,50] 0 F7 Shekel's Foxholes 2 [−65.536,65.536] 1 F8 Six-Hump Camel-Back 4 [−5,5] − 1.0316 F9 Goldstein-Price 2 [−2,2] 3 F10 Shekel's Family 4 [0,1] − 10.4028 表 3 不同算法对基准测试函数寻优结果
Table 3. Optimization results of different algorithms for benchmark functions
函数 GWO WOA HHO ALO AO Improved AO F1 AVG 1.40×10−127 7.91×10−121 4.76×10−117 2.67×10−10 3.71×10−174 3.95×10−323 STD 6.08×10−127 2.45×10−120 2.21×10−116 1.24×10−10 0.00 0.00 Best 5.36×10−135 1.12×10−127 2.56×10−129 9.62×10−11 9.38×10−182 0.00 F2 AVG 2.31×10−71 4.86×10−66 6.93×10−65 1.94×10−5 7.45×10−88 5.37×10−166 STD 6.58×10−71 2.58×10−65 2.29×10−64 4.16×10−5 2.29×10−87 0.00 Best 3.10×10−74 6.20×10−73 1.69×10−75 5.99×10−6 4.82×10−94 1.17×10−174 F3 AVG 2.76×10−67 1.17×10−2 2.11×10−106 2.53×10−9 1.13×10−170 0.00 STD 6.84×10−67 2.78×10−2 1.16×10−105 1.27×10−9 0.00 0.00 Best 1.91×10−74 3.49×10−6 1.89×10−123 3.96×10−10 5.12×10−181 0.00 F4 AVG 6.10×10−44 2.27×10−9 2.90×10−58 1.54×10−5 6.46×10−88 8.25×10−166 STD 1.49×10−43 7.34×10−9 1.11×10−57 2.98×10−6 2.33×10−87 0.00 Best 1.01×10−47 3.01×10−25 1.68×10−64 1.06×10−5 7.89×10−95 2.23×10−182 F5 AVG 4.00×10−15 2.46×10−15 4.44×10−16 5.49×10−2 4.44×10−16 4.44×10−16 STD 0.00 2.02×10−15 0.00 3.01×10−1 0.00 0.00 Best 4.00×10−15 4.44×10−16 4.44×10−16 3.63×10−6 4.44×10−16 4.44×10−16 F6 AVG 3.00 3.39×10−2 4.18×10−7 2.16×102 1.44×10−7 2.37×10−4 STD 4.72×10−1 3.06×10−2 6.39×10−7 1.72×101 2.16×10−7 4.32×10−4 Best 2.08 9.24×10−3 1.19×10−11 1.83×102 4.47×10−11 1.18×10−8 F7 AVG 9.98×10−1 9.98×10−1 9.98×10−1 9.98×10−1 9.98×10−1 9.98×10−1 STD 1.13×10−11 8.48×10−15 1.04×10−15 2.31×10−16 8.48×10−11 3.92×10−9 Best 9.98×10−1 9.98×10−1 9.98×10−1 9.98×10−1 9.98×10−1 9.98×10−1 F8 AVG −1.03 −1.03 −1.03 −1.03 −1.03 −1.03 STD 1.01×10−9 7.23×10−15 4.25×10−16 8.87×10−15 5.38×10−6 2.44×10−4 Best −1.03 −1.03 −1.03 −1.03 −1.03 −1.03 F9 AVG 2.99 3.00 2.98 2.98 3.00 3.00 STD 1.71×10−7 1.00×10−9 3.01×10−14 4.99×10−14 3.24×10−4 6.16×10−15 Best 2.99 3.00 2.98 2.98 3.00 3.00 F10 AVG −1.02×101 −1.04×101 −6.86 −9.35 −1.04×101 −1.04×101 STD 9.70×10−1 8.75×10−7 2.55 2.15 5.73×10−5 3.22×10−2 Best −1.04×101 −1.04×101 −1.04×101 −1.04×101 −1.04×101 −1.04×101 表 4 Wilcoxon秩和检验结果
Table 4. Wilcoxon rank sum test result
对比算法 单峰函数 多峰函数 固定维数多峰函数 Improved AO vs. GWO 6.39×10−4 2.86×10−2 1.19×10−2 Improved AO vs. WOA 2.48×10−4 6.43×10−2 7.80×10−3 Improved AO vs. HHO 1.55×10−3 6.26×10−2 3.97×10−3 Improved AO vs. ALO 1.00×10−5 2.86×10−2 7.80×10−3 Improved AO vs. AO 9.58×10−3 7.62×10−2 5.69×10−2 表 5 改进AO算法种群数量(N)的敏感性分析
Table 5. Sensitivity analysis of the Improved AO for the number of population members (N)
函数 种群数量值 100 200 300 400 F1 0.00 0.00 0.00 0.00 F2 5.13×10−167 1.16×10−167 7.23×10−171 3.09×10−176 F3 0.00 0.00 0.00 0.00 F4 3.87×10−181 3.87×10−187 5.83×10−195 0.00 F5 4.44×10−16 4.44×10−16 3.45×10−18 1.12×10−21 F6 1.49×10−5 1.35×10−6 2.58×10−6 2.33×10−7 F7 9.98×10−1 9.98×10−1 9.98×10−1 9.98×10−1 F8 −1.03 −1.03 −1.03 −1.03 F9 3.02 3.02 3.01 3.01 F10 −1.04×10−1 −1.04×10−1 −1.04×10−1 −1.04×10−1 表 6 改进AO算法迭代次数(T)的敏感性分析
Table 6. Sensitivity analysis of the Improved AO for the number of Iterations (T)
函数 最大迭代次数 200 400 600 800 F1 1.68×10−225 0.00 0.00 0.00 F2 5.67×10−108 3.64×10−145 1.52×10−167 6.26×10−170 F3 2.28×10−217 0.00 0.00 0.00 F4 5.91×10−109 5.61×10−159 5.85×10−165 2.99×10−168 F5 4.44×10−16 4.44×10−16 3.25×10−17 1.93×10−17 F6 3.93×10−5 1.79×10−5 1.45×10−6 9.95×10−7 F7 9.98×10−1 9.98×10−1 9.98×10−1 9.98×10−1 F8 −1.03 −1.03 −1.03 −1.03 F9 3.01 3.01 3.01 3.01 F10 −1.04×10−1 −1.04×10−1 −1.04×10−1 −1.04×10−1 表 7 径向畸变参数估计结果
Table 7. Radial distortion parameter estimation results
序列 Ref [8] Ref [11] Ref [12] Ours (a) −1.03×10−5 −1.01×10−5 −1.01×10−5 −1.01×10−5 (b) −1.02×10−6 −1.02×10−6 −1.02×10−6 −1.02×10−6 (c) −1.05×10−7 −0.96×10−7 −0.97×10−7 −1.02×10−7 (d) −1.07×10−8 −1.04×10−8 −1.04×10−8 −1.02×10−8 (e) −1.02×10−6 −1.03×10−6 −1.01×10−6 −1.01×10−6 (f) −1.02×10−5 −1.01×10−5 −1.01×10−5 −1.01×10−5 表 8 畸变参数估计误差
Table 8. Estimation error of the distortion parameter
表 9 全景图像畸变参数估计结果
Table 9. Omnidirectional image distortion parameter estimation results
序列 图像大小 畸变参数 畸变中心 (a) $2\;048 \times 1\;536$ 2.2613 ×10−6( 1091.72 ,695.14)(b) $2\;048 \times 1\;536$ 2.1983 ×10−6( 1095.62 ,692.57)(c) $2\;048 \times 1\;536$ 2.3564 ×10−6( 1096.34 ,695.83)(d) $2\;048 \times 1\;536$ 2.2083 ×10−6( 1094.61 ,696.53)(e) $4\;352 \times 3\;264$ 3.2517 ×10−6(517.86,382.15) (f) $4\;352 \times 3\;264$ 2.8476 ×10−6(516.43,380.93) -
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