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为了精确计算离轴三反相机的焦距以保证其测绘精度,对经典测绘模型和相关公式进行了必要的修正。首先,重新定义了离轴三反测绘相机的交会角,并对经典焦距计算公式做了修正;其次,分析了地球曲率对离轴三反测绘相机焦距计算的影响,进一步修正了焦距计算公式。实例计算表明:当要求地面像元分辨率为2m,在CCD像元尺寸为8μm,轨道高度为700km,离轴角为7°条件下,应用经典计算公式得出的斜视相机焦距与应用修正后的计算公式所得出的斜视相机焦距相对偏差达到2.6%,说明对测绘精度影响很大。因此,在采用离轴三反相机进行摄影测量时,斜视相机焦距的计算应考虑离轴角后对经典公式进行必要的修正,而正视相机的焦距计算可以沿用经典计算公式。
In order to accurately calculate the focal length of the off-axis three-reverse camera to ensure the accuracy of its mapping, the necessary amendments to the classical mapping model and related formulas were made. First, the intersection angle of the off-axis three-contrast mapping camera is redefined and the classical focal length calculation formula is revised. Secondly, the influence of the curvature of the earth on the calculation of the focal length of the off-axis three-inverse mapping camera is analyzed, and the calculation formula of the focal length is further amended. The calculation example shows that when the resolution of the ground pixel is 2m, the CCD camera size is 8μm, the height of the track is 700km and the off-axis angle is 7 °, the focal length of the strabismus camera calculated by the classical formula and the application after correction Of the formula obtained by the strabismus camera focal length relative deviation of 2.6%, indicating a great impact on the accuracy of the survey. Therefore, the use of off-axis three-camera for photogrammetry, strabismus camera focal length calculation should take into account the off-axis angle after the necessary amendments to the classical formula, and face the camera focal length can be calculated using the classical formula.