太阳影子定位模型的研究及应用

Research of Shadow Localization Model and Its Application

摘要: 本文利用影子随着时间的变化，建立了太阳影子定位的模型。首先对视频中提取的图像进行裁剪、灰度化以及二值化的预处理，可以大大降低图像处理的计算量；其次利用透视变换，求出视频中实际的杆影长，对于受测量误差影响较大的异常数据，我们给予剔除；然后利用天文学中太阳运行轨迹相关理论，我们给出了太阳高度角，实际杆影长等的公式；最后，在已知杆长和未知杆长的情况下，把模型定位问题转化成求解经纬度和日期的非线性优化问题。通过比较，求解结果较好地吻合了实际的拍摄地点和日期。

Abstract: With the length variation of pole’s shadow, we construct a localization model. Firstly, in order to reduce the work of images processing, we preprocess the extracted images, including cutting, gray processing, binarization processing, etc. Secondly, applying perspective transform, we get the actual length of pole’s shadow in video. For some images, measurement error results in some abnormal data of pole’s length, consequently, we remove them. Thirdly, using solar paths’ related theory in astronomy, we obtain formulas of the solar elevation angle and the shadow’s length. Lastly, whether the real length of pole in video is known or not, we transform the localization model into solving the longitude, latitude, and date of the nonlinear optimization problem. By comparison, the results of the solution are in good agreement with the actual shooting location and date.