Photometric modeling to characterize planetary surfaces in the solar domain

To understand the formation and evolution of landscapes, or to develop
exploration strategies for future planetary exploration missions, we
need to know the physical characteristics of terrestrial and planetary
surfaces. Photometry is one method of studying these characteristics
remotely, via the bidirectional reflectance distribution function
(BRDF). There are several BRDF models, both semi-empirical and physical,
capable of simulating the BRDF of natural surfaces. The inversion of
these models, of which the Hapke model is the most widespread in the
scientific community, has been widely used over the last few decades to
reveals the physical properties of complex surface, including surface
roughness, grain size and shape, micro-texture, mineral composition and
so on. However, this method has rarely been applied on a large scale on
Earth, due to a number of difficulties. Moreover, model validation is
still largely qualitative. Two study sites have been selected for our
research: (1) The Asal-Ghoubbet rift (Republic of Djibouti), remarkable
for its arid terrain, serving as a potential analogue for
extraterrestrial surfaces; (2) The near side of the Moon, in particular
the landing sites of the Apollo missions. These sites are of great
interest as they offer a wide variety of orbital and in situ data:
satellite images, photos acquired at different scales, lab samples. One
of the original features of this thesis work is the use of Pleiades
imagery for the Earth and Moon, and the inversion of the Hapke model on
the BRDF extracted from each pixel to generate maps of model parameters
(between four and six) depending on the areas studied. We sought to
decipher the physical meaning of each parameter and attempted to compare
them with field measurements. Field data includes multi-angular
photographs taken by drone or by hand, to create digital elevation
models (DEM) using photogrammetry, and samples for spectral measurements
and identification of chemical constituents. Finally, the relationship
between the physical properties of the surface and its BRDF was
investigated using the DART-Lux ray-tracing model.


The jury is composed of :
Jean-Louis Roujean, Research Director (CNRS) (Rapporteur)
Mathieu Vincendon, Associate Professor (Université Paris-Saclay) (Rapporteur)
Charles Bachmann, Professor (Rochester Institute of Technology) (Examiner)
Sonia Fornasier, Professor (Université Paris Cité) (Examiner)
Antoine Pommerol, Associate Professor (University of Bern) (Examiner)
Ewelina Rupnik, Researcher (IGN) (Examiner)
Sylvain Douté, Research Director (CNRS) (Guest)
Stéphane Jacquemoud, Professor (Université Paris Cité) (PhD Advisor)
Antoine Lucas, Researcher (CNRS) (PhD Advisor)