基于同步GCPs与像点估算的香蕉园多目标植株精确地理定位算法

Precise geolocation algorithm for multi-target plants in banana plantations based on synchronized GCPs and image point estimation

  • 摘要: 【目的】基于同步地面控制点(GCPs)与像点估算建立香蕉园多目标植株精确地理定位算法(SGIE-MPL),为实现香蕉园的单株级精细管控及指引农机与农业机器人自主规划路径导航等提供技术支持。【方法】基于同步GCPs与像点估算建立SGIE-MPL算法,通过引入同步GCPs实现对目标的同步定位,并采用相机视场角建模免去繁杂的标定程序;通过香蕉株干基部点像素坐标估算解决因植株高度引起的待定位目标点与GCPs不共面、投影差对定位精度造成影响的问题,最终实现对单株级植株的精准地理定位。在此基础上,通过与基于相机与地球模型的地面目标定位算法(CTLA)和基于单目视觉的目标定位模型(MV-OLM)进行对比,以及在多重因素耦合条件下检验SGIE-MPL算法的定位精度,并开展多目标工程化试验验证其稳定性。【结果】在20和30 m的无人机飞行高度下,SGIE-MPL算法定位精度的超出指标值为0.04 m,远小于香蕉的平均叶片长度,且各组试验的平均绝对误差(MAE)与均方根误差(RMSE)均小于3.00 m,算法达标率(P)为98.52%。在相同测试条件下,SGIE-MPL算法在MAE、RMSE及P等3个指标上均明显优于相似技术路线的CTLA算法和MV-OLM算法。在不同植株高度与无人机飞行高度(20~50 m)等多因素耦合条件下,SGIE-MPL算法仍具备良好的鲁棒性和定位精度;基于大型香蕉园场景的SGIE-MPL算法多目标工程化试验结果表明,在包含462个待定位目标的图像中,目标检测效果图与地图标记吻合,说明SGIE-MPL算法能稳定计算出所有目标的地理坐标。【结论】基于同步GCPs与像点估算的SGIE-MPL算法联合集成化软件平台,能在香蕉园多目标密集场景中实现单株级植株的精准地理定位,其P为98.52%,明显优于CTLA算法和MV-OLM算法,且仅需常规主流品牌的消费级无人机,即可为香蕉园的单株级精细管控及指引农机与农业机器人自主规划路径导航等提供技术支持。

     

    Abstract: 【Objective】This study aimed to establish a precise geolocation algorithm for multi-target plants in banana plantations based on synchronized ground control points (GCPs) and image point estimation (SGIE-MPL), thereby providing technical support for tasks such as single-plant-level precision management in banana cultivation, autonomous path planning and navigation of agricultural machinery and robots.【Method】The SGIE-MPL algorithm was established based on synchronized GCPs and image point estimation to achieve concurrent localization of targets with introduction of synchronized GCPs, and camera field of view modeling was utilized to eliminate cumbersome calibration procedures. Pixel coordinates of banana plant base points were estimated to address plant height-induced problems (non-coplanarity between target points to be localized and GCPs and localization accuracy affected by projection error) for single-plant-level precise geolocation. Based on this, the camera and terrain model-based localization algorithm (CTLA) and the monocular vision-based object localization model (MV-OLM) were compared, the localization accuracy of SGIE-MPL algorithm was tested under multi-factor coupled conditions, and the stability was tested by performing multi-target engineering trials.【Result】At unmanned aerial vehicle (UAV) flight altitudes of 20 m and 30 m, the SGIE-MPL algorithm achieved localization accuracy with an excess indicator value of 0.04 m, far lower than the mean leaf length of banana; the mean absolute error (MAE) and root mean square error (RMSE) were less than 3.00 m across test groups, with the algorithm compliance rate (P) of 98.52%. Under the same test conditions, the SGIE-MPL algorithm outperformed CTLA and MV-OLM algorithms with similar technological pathways in terms of three indicators (MAE, RMSE, and P). Under multi-factor coupled conditions such as plant height and UAV flight altitude (20-50 m), the SGIE-MPL algorithm demonstrated superior robustness and localization accuracy. According to the results of SGIE-MPL multi-target engineering test based on large-scale banana plantation, for the 462 target points to be localized, the target detection image aligned with the map, indicating that the SGIE-MPL algorithm could calculate all geographic coordinates of targets stably.【Conclusion】The SGIE-MPL integrated software platform based on synchronized GCPs and image point estimation can realize single-plant-level precise geolocation in the dense multi-target scene of banana plantation, with the P of 98.52%, which ob-viously outperforms the CTLA and MV-OLM algorithms. It requires only consumer-grade UAVs to provide technical support for tasks such as single-plant-level precision management in banana plantations, autonomous path planning and navigation of agricultural machinery and robots.

     

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