Determining the precise location of low altitude ground based lidar returns is the topic of this paper. This involves consideration of the curvature of the earth and atmospheric refractivity. A closed form geometrical optics solution is obtained for a spherical earth and a modified index of refraction which has a quadratic dependence on altitude as determined by a linear temperature profile. In this way the ray path of a laser can be plotted as a function of range and azimuth in a variety of realistic atmospheres. Resulting ray paths and corresponding altitude errors are presented for near horizon measurements.
展开▼
