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Structure-from-Motion photogrammetry has recently become a cheap and efficient method to reconstruct accurate and highly-resolved 3D Digital Outcrop Model (DOM) from a single set of images. This enables the 3D visualization of hardly accessible and/or remote geological scenes, which is of strong interest for planetary bodies. This paper focuses on the reconstruction of the DOM of the Kimberley outcrop (Gale crater, Mars) using the Agisoft PhotoScan Professional software. This software is used to compute an accurate, scaled and georeferenced 3D mesh of this outcrop from set of multi-scale images taken by the Mars Science Laboratory rover Curiosity. This model was merged with a 3D model computed from orbital images from the High Resolution Imaging Science Experiment camera (HiRISE) to provide the context. One of the challenges is to integrate data coming from different cameras (with varying optical parameters) not specifically designed for 3D rendering, and with limited points of views. While the obtained DOM allows to observe and characterize geological features of Kimberley's sedimentary series, classic viewing methods through a 2D screen limits the understanding of the real 3D geometry and scale of the outcrop, as there is no feature such as trees or roads on Mars to provide size references to the user. To overcome this issue and facilitate the interpretation of the DOM, the latter is integrated into a Virtual Reality (VR) environment that enables one or several users working in a collaborative mode to experience a real scale, reliable and realistic depiction of the actual geometries of the geological features reconstructed on the mesh. Precise and accurate description, contextualization of the samplings and mapping of the Kimberley outcrop can therefore be achieved in VR allowing for more precise characterization and interpretations, the same way one would do on a real geological field trip. • Digital Outcrop Modeling of a Curiosity rover field site on Mars. • Integration into Virtual Reality for real scale visualization of the features. • VR-enabled geological analysis of the accurately reconstructed Martian outcrop. • VR allows for characterization of previously underrated sedimentological features. [ABSTRACT FROM AUTHOR]

Reconstruction of highly-resolved Digital Outcrop Model (DOM) using Structure-from-Motion photogrammetry is a low-cost but very effective method to explore and study remote planetary outcrops. Extensive data gathered by Mars Science Laboratory (MSL) rover Curiosity can be used to produce models of specific outcrops visited by the rover in the Gale Crater, on Mars. Integration into a Virtual Reality (VR) environment of these DOM enables one or several users to experience a reliable and realistic depiction of the actual geometries of the geological features, which is usually prevented by classic viewing methods on computer screens. Also, use of a VR environment authorizes the observation at real scale of various sedimentary series, structures and objects present at an outcrop, the same way they would on a real field. Moreover, this practice allows for a very precise and accurate characterization, description and therefore mapping of the features, as well as the contextualization of the sampling and remote analyses underwent by the Curiosity rover within their geological setting (e.g. ChemCam Laser-Induced Breakdown Spectrometer and Remote Micro-Imager data). Here, we focus on the Kimberley outcrop, traversed by Curiosity in 2014 between martian sols 603 and 630. This section presents a sedimentary succession with unusually high potassic content (Le Deit et al., JGR-Planets, 2016). However, poorly constrained stratigraphic relations between the series of the Kimberley Formation and its local to regional surroundings prevent further understanding of the exact extent of these accumulations and their significance within the broader Gale Crater paleoenvironmental scheme. Such questions highlight the need for a new finer mapping of, first, the outcrop itself to notably achieve precise characterization at the cm-scale of the Mount Remarkable butte; and then of the various structures present in the immediate vicinity of the outcrop. We therefore propose to use a custom true color highly resolved (up to the mm-scale) DOM of the Kimberley outcrop integrated into a VR environment to achieve precise and accurate mapping of the area and of the different geomorphological and sedimentological features (beds, structures and contacts alike). This represents a first step toward a better understanding of the intra- and inter-formational relations of the Kimberley series.We acknowledge the EU H2020 PlanMap project for supporting this work. [ABSTRACT FROM AUTHOR]

Structure-from-Motion (SfM) photogrammetry is an efficient, low-cost and powerful method to reconstruct Digital Outcrop Models (DOM) only from a set of overlapping photos. Apparent displacement of similar points across the set are used to determine the position of these points within a 3D space, and therefore recreate the tri-dimensional geometry (3D mesh) of the photographed objects. This method has recently been explored for remote planetary exploration such as that of the Gale Crater, Mars, thanks to the extensive imagery data from the Mars Science Laboratory (MSL) rover Curiosity.Here, we reconstructed a DOM of the Kimberley outcrop, traversed by Curiosity between sols 603 and 630, based on a comprehensive set of multi-scale photos gathered by 3 different imaging instruments aboard Curiosity, namely the navigational cameras (NavCam, 530 photos), mast cameras (MastCam, 1443 photos) and the Mars Hand Lens Imager (MAHLI, 32 photos).Despite the difference in resolution, colorization (greyscale vs full color), coverage and overlap parameters across these three different image data, we were able to compute a highly resolved full color DOM of the Kimberley outcrop using Agisoft PhotoScan software. Moreover, use of PhotoScan's embedded advanced geospatial features allowed us to obtain a geographically constrained DOM and a direct and proper scaling of the model (validated using the rover's tracks on the model).As the Kimberley outcrop presents a sedimentary succession with unusually high potassic content (Le Deit et al., JGR-Planets, 2016), the stratigraphic relations within this series and with its immediate to local surroundings are critical to understand the extent of these potassic accumulations and their signification from a paleoenvironmental point of view. We therefore integrated this high-resolution DOM into a collaborative Virtual Reality (VR) environment. VR lets one or several users observe at real scale the various sedimentary series and structures of the outcrop. This way, precise and accurate description, quantification and mapping of the outcrop is possible, allowing for more precise characterization and interpretation, as well as enabling contextualization within the local geological setting of the various data gathered by Curiosity (e.g. ChemCam Laser-Induced Breakdown Spectrometer and Remote Micro-Imager data).Collaborative VR exploration and characterization of photogrammetrically reconstructed reliable DOM is paving the way for remote geological exploration of Martian outcrops and other planetary bodies in near future.We acknowledge the EU H2020 PlanMap project for supporting this work. [ABSTRACT FROM AUTHOR]