Photometric Recovery of Ortho-Images Derived from Apollo 15 Metric Camera Imagery

The topographical and photometric reconstruction of the moon from Apollo metric data has gained attention to support manned mission planning since the NASA has been working on return to the moon in 2004. This paper focuses on photometric recovery of the moon surface from Apollo orbital imagery. The statistical behavior of photons generates the scene radiance which follows a continuous Poisson distribution with the mean of surface radiance. The pixel value is determined by the camera response of sensor exposure which is proportional to scene radiance and exposure time. The surface radiance, exposure time and camera response are estimated by the maximum likelihood method for sensor exposure. The likelihood function is highly nonlinear and we were unable to find an estimator in closed form. Grouping the three sets of parameters (surface radiance, exposure time, and camera response), an EM-like juggling algorithm is proposed to determine the one family of parameters from the others. The photometric recovery of otho-images derived from Apollo 15 metric camera imagery was presented to show the validity of the proposed method.