为了解决分光轴式多源图像融合系统近距离图像配准问题, 建立了一种双目成像配准模型, 分析了分光轴系统的镜头中心距对配准精度的影响。该模型以物点对不同镜头的入射角差为切入点, 以入射角差作为配准精度的判别依据, 分析了配准精度随镜头中心距和物距的变化关系。结合探测器角分辨率和光轴调校精度, 给出了分光轴系统像素级配准的距离范围计算公式, 并且引入光轴初始夹角和图像像素平移量, 实现近距离变视距图像配准。计算结果表明: 分光轴系统光轴平行时可对某一最近距离至无穷远范围内配准, 当调节系统对更近距离配准时, 可在一段有限范围内配准, 缩小镜头中心距和提高光轴调校精度可以扩大系统的配准范围。利用提出的配准距离范围计算方法, 结合目标测距, 实现了分光轴式红外与可见光图像融合系统近距离变视距图像配准。

In order to solve the problem of close range image registration of multi-source image fusion system with a separate optical axis structure, a registration model of binocular imaging system was established to analyze the impact of the lens center distance on the registration accuracy. The incidence angle difference of object points to different lenses was considered in this model, which determined the registration accuracy. In this way, the relationships of registration accuracy, lens center distance and object distance were analyzed. Finally, considering the angular resolution of detectors and optical axis calibration accuracy, computational formula of the distance range of pixel-level registration of separate optical axis system was given, which could be adjusted for variable close range image registration by the initial angle of two optical axes and the pixel translation of the image. Calculation results indicate that the separate optical axis system can achieve pixel-level registration from a closest distance to infinity, when the optical axes are parallel. If the system is adjusted to register for a closer distance, the registration range will become finite. Smaller lens center distance and higher optical axis calibration accuracy will help to expand the registration range. Finally, with the calculated registration range and the measured target distance, the variable close range image registration of infrared and visible light image fusion system with separate optical axis structure has been achieved.