Photogrammetric 3D reconstruction of Apollo 17 Station 6: From boulders to lunar rock samples integrated into virtual reality
Résumé
Apollo 17 astronauts spent three days exploring the Taurus Littrow Valley on the Moon in 1972. During their
third Extravehicular Activity, they spent more than one hour at Station 6, a geologic waypoint consisting of three
big and two small fragments of a boulder that rolled down the North massif. We have used all the available scanned
digital Apollo photos taken by the astronauts at this Station 6 to compute a comprehensive 3D model of the
explored area. We used Structure From Motion photogrammetry to automatically derive the position of each of
the 154 available images using their overlap. All images were aligned in a single photogrammetric project, which
allows on one hand to automatically visualize the astronaut positions during their investigations, and on the other
hand to reconstruct in 3D the three main pieces of boulders, therefore constraining their respective size and
orientation. In addition to the boulders, we show that the 3D reconstruction by photogrammetry can also be applied
to the rock samples taken from the boulders themselves. These samples were systematically photographed from
multiple angles at the LPI during the 70s when brought back to Earth. For the reconstruction, we used scanned
archived images representing 16 stereoscopic pairs, to compute 3D models of samples 76015, 76215, 76315 and
76275. These models might play a role in preservation as some of the samples, latter sawed for analysis, do not
exist anymore in their pristine form. 3D models of the boulders and rock samples can then be manipulated and
visualized on a web-based platform. 3D models have also been integrated into a virtual reality scene in order to
provide the possibility to investigate their properties at full scale in an immersive and collaborative way. The
knowledge of the samples position and orientation directly in their context might for example provide additional
constrains to better understand processes such as the space weathering alteration due to micrometeorite impacts
and solar wind particle. 3D photogrammetric reconstructions using images taken by rovers and/or astronauts might
be one of the basic techniques to consider in forthcoming lunar missions in order to maximize their scientific,
educational and outreach return.
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