OPTIMAL OBSERVATIONAL CONDITIONS OF THE PLANETARY SURFACE FOR THE RELIEF RECONSTRUCTION WITH PHOTOMETRIC METHOD. S. I. Skuratovsky, I. A. Dulova,

Introduction. High-resolution topographic information is important in different applications for the study of planetary surfaces: their evolution, state, and properties. The most precise topographic data are obtained through direct measurements with different altimeters on board of spacecrafts (e.g., [1]). Indirect techniques for surface height estimates involve photogrammetry (e.g., [2]), photoclinometry (e.g., [3]), and interferometry (e.g., [4]). Illumination-viewing conditions for observations of planetary surface are important for relief reconstruction with indirect methods. These conditions are usually limited during real missions by spacecraft orbit geometry, particular time of observations, spacecraft life time and scientific program which lead to the limited number of observations of the same surface areas. In the present work we analysis relationship between illumination-viewing conditions of surface observations and spatial error distribution arose during surface relief reconstruction with photometric method proposed in [5]. The method is the most mathematically correct and can be classified as a photoclinometry method since it uses the fact that observed brightness of the surface depends on the surface orientation. The study was made using simulated observations of the test surface in the optical wavelength range and for radar experiments. Photometric method for the planet relief determination. The photometric method used here is based on the statistical approach to a problem of surface relief determination from a set of images taken under different viewing conditions. The brightness (J) of an element with coordinates (x, y) in the j-th image can be written as