Viewpoint Planning for Robot Photogrammetry Based on Initial Pose Estimation via Deep Learning
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摘要: 针对机器人摄影测量中离线规划受初始位姿标定影响的问题, 提出融合初始位姿估计的机器人摄影测量系统视点规划方法. 首先构建基于YOLO (You only look once) 的深度学习网络估计被测对象3D包围盒, 利用PNP (Perspective-N-point)算法快速求解对象姿态; 然后随机生成机器人无奇异无碰撞的视点, 基于相机成像的2D-3D正逆性映射, 根据深度原则计算每个视角下目标可见性矩阵; 最后, 引入熵权法, 以最小化重建信息熵为目标建立优化模型, 并基于旅行商问题(Travelling saleman problem, TSP)模型规划机器人路径. 结果表明, 利用深度学习估计的平移误差低于5 mm, 角度误差低于2°. 考虑熵权的视点规划方法提高了摄影测量质量, 融合深度学习初始姿态的摄影测量系统提高了重建效率. 利用本算法对典型零件进行摄影测量质量和效率的验证, 均获得优异的位姿估计和重建效果. 提出的算法适用于实际工程应用, 尤其是快速稀疏摄影重建, 促进了工业摄影测量速度与自动化程度提升.Abstract: Aiming at the problem that offline planning of robot photogrammetry is affected by the initial pose calibration, a viewpoint planning method of robot photogrammetry system incorporating initial pose estimation is proposed. First, we construct a YOLO (you only look once)-based deep learning network to estimate the 3D bounding box of the measured object, and utilize the PNP (perspective-N-point) algorithm to quickly solve the object pose; Second, we randomly generate non-singular and collision-free viewpoints. Based on the 2D-3D forward and inverse mapping of camera imaging, we calculate the target visibility matrix under each perspective according to the depth principle; Finally, the entropy-weighted method is introduced, the optimization model is established with the goal of minimizing the reconstruction information entropy afterward the robot path is planned based on the TSP (travelling salesman problem) model. The results show that the translation error estimated via deep learning is less than 5 mm, and the angular error is less than 2°. The viewpoint planning method considering entropy weight improves the quality of photogrammetry. Simultaneously, the reconstruction speed is increased. It obtains excellent pose estimation and reconstruction results when utilizing the algorithm to verify the photogrammetric quality and efficiency of more typical parts. The proposed algorithm is extendable to practical engineering applications, especially for rapid sparse photogrammetry, improving the speed and automation of industrial photogrammetry.
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Key words:
- Photogrammetry /
- robot /
- deep learning /
- viewpoint planning /
- visibility matrix /
- entropy weight method
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表 1 信息熵权有效性验证表
Table 1 Effectiveness test for entropy weight
对比实验 目标函数 优化的视
点数(个)点云数(个) A $x^*=\min \displaystyle \sum\limits_{i=1}^N { {w_i}{x_i} }$ 21 21509 B $x^*=\min \displaystyle \sum\limits_{i=1}^N { {x_i} }$ 20 18360 C $x^*=\min \displaystyle \sum\limits_{i=1}^N { {x_i} }$ 21 = 20 (B) +
1 (288)15344 表 2 综合权重和初始姿态下重建质量对比
Table 2 Comparison of reconstruction quality with weight and first-sight pose
有权重 无权重 有初始位姿约束 无初始位姿约束 有初始位姿约束 无初始位姿约束 视点索引 1, 13, 100, 113, 143,
149, 173, 189, 190,
196, 207, 269, 272, 28013, 100, 113, 143,
149, 173, 189, 190, 196,
207, 269, 272, 2801, 17, 28, 38, 45, 61,
66, 74, 89, 91, 92, 107,
113, 127, 185, 189,
207, 249, 269, 28014, 35, 43, 45, 56, 59,
73, 75, 89, 111, 127, 149,
162, 185, 189, 207, 249,
256, 274, 281三维点云 点数量 10584 11451 7703 9571 注: 有初始位姿约束下,索引为1的视点需被约束保留. 表 3 利用深度学习位姿估计的摄影测量效率对比
Table 3 Comparison on effectiveness of photogrammetry with estimated pose using deep learning
点个数 重建时间 (s) 有初始位姿约束 无初始位姿约束 数量变化 (%) 无位姿估计 有位姿估计 效率提升 (%) 球体 15635 16489 5.18 157 133 15.29 柱体 10138 11503 11.87 182 155 14.84 凹台 11472 12640 9.24 102 83 18.63 -
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