Using LROC WAC data for Lunar surface photoclinometry

All available lunar digital elevation models, e.g., SELENE LALT DEM, SELENE DTM LISM, Chang'E-1 LAM DEM, GLD100, SLDEM2015, have certain disadvantages, including insufficient resolution and/or the presence of defects as well as mismatching reference coordinate systems, making it difficult to incorporate the topographic effect on photometric LROC WAC observations. We here propose a photoclinometry technique that can be used to account for this effect. To do so, we modify our algorithm used to construct seamless photometric mosaics (Korokhin et al., PSS 2016, 122, 70-87) to determine local slopes simultaneously with parameters of photometric function during the mosaicing procedure. This technique can be useful for improvement of quality of remote sensing of surfaces with complex topography. We also develop a new algorithm for constructing the lunar digital elevation model based on the simultaneous use of laser altimetric measurements (LRO LOLA) and local longitudinal slopes obtained photoclinometrically from LROC WAC data. The algorithm provides a digital elevation model with accuracy and resolution not worse than SLDEM2015, yet demonstrating significantly fewer defects and artifacts. High-quality topo data can be useful for geology, geomorphology and for navigation/exploration/mission planning.