USING VIRTUAL REALITY TOOLS TO CHARACTERIZE AND MEASURE SEDIMENTARY SERIES IN GALE CRATER: A CASE STUDY

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USING VIRTUAL REALITY TOOLS TO

CHARACTERIZE AND MEASURE SEDIMENTARY SERIES IN GALE CRATER: A CASE STUDY

Gwénaël Caravaca, Stéphane Le Mouélic, Nicolas Mangold, Laetitia Le Deit

To cite this version:

Gwénaël Caravaca, Stéphane Le Mouélic, Nicolas Mangold, Laetitia Le Deit. USING VIRTUAL

REALITY TOOLS TO CHARACTERIZE AND MEASURE SEDIMENTARY SERIES IN GALE

CRATER: A CASE STUDY. 52nd Lunar and Planetary Science Conference, Lunar and Planetary

Institute, Mar 2021, The Woodlands, United States. �10.5281/zenodo.4288287�. �hal-03143070�

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USING VIRTUAL REALITY TOOLS TO CHARACTERIZE AND MEASURE SEDIMENTARY SERIES IN GALE CRATER: A CASE STUDY. G. Ca ra va ca^1*, S. Le Mouélic¹, N. Ma ngold¹, L. Le Deit¹. ¹UMR CNRS 6112 LPG La bora toire de Pla nétologie et Géodyna mique, Université de Na ntes, Fra nce, *gwena el.ca ra va ca @univ-na ntes.fr

Introduction: The a pplica tion of Virtua l Rea lity (VR) to resea rch ends is a recent but growing pra ctice a mong the community. This technique unlocks previously underra ted possibilities to study ha rdly a ccessible a rea s, which is pa rticula rly suited for pla neta ry bodies [e.g. 1, 2]. Indeed, a wea lth of da ta (ima gery, eleva tions, minera logy, etc.) ga thered by orbita l a nd ground-ba sed robotic probes ca n be used to compute 3D models that a re rea dily usa ble to genera te virtua l environments, that will in turn be used to a ddress geologic questions. Sev- era l solutions to visua lize a nd study such 3D da ta are currently in development like Pro3D [3] or Cos- moScoutVR [4].

Here we ha ve set up a n integra ted set of mea surement tools, specifica lly designed to replica te a “fieldwork experience” in VR. In this case study, we present such innova tive a nd fully-integra ted VR tools. They a l- low the user to fully ta ke a dvantage of a n immersive virtua l environment a ccura tely recrea ting a n a rea centered a round the Kimberley outcrop (Ga le cra ter, Ma rs), ex- plored by the Ma rs Science La bora tory rover Curiosity in 2014. These tools a llows users to perform geologica l cha ra cteriza tion, mea surements a nd observa tions a s if they were physica lly there (Fig. 1).

Fig. 1 Illustra tion of a geologist using Virtua l Rea lity hea dset a nd controllers to explore a recrea tion of the Kimberley outcrop (Ga le cra ter, Ma rs), a nd ta king mea surements using dedica ted VR tools.

Entry data and creation of the Virtual Environ- ment: To propose a n immersive experience, the virtua l environment is genera ted using a videoga me engine [5].

This solution provides a versa tile wa y to integra te, ma - nipula te a nd intera ct with la rge sets of da ta , those being necessa ry to recrea te a n immersive a nd a ccura te repre- senta tion of the a ctual terra ins. This virtua l environment is genera ted from a georeferenced multi-sca le set of entry da ta comprising both orbita l-derived a nd ground-

ba sed 3D meshes. La rgest-sca le orbita l models (gener- a ted from HiRISE da ta ) a re used to visua lize the entire study a rea a nd to provide a context a nd ba ckground.

Closer perspectives a re possible using photogra mmetric ground-ba sed models (computed from photos ta ken by the Curiosity rover) offering a n unprecedented resolution to study a t a very fine sca le the specificities of the Kimberley outcrop [6].

VR-enabled measurement tools: A set of innova - tive VR-ena bled tools ha s been designed to provide the users with the possibility to explore a nd cha ra cterize the virtua l environment a s if they were a ctua lly present there. The utiliza tion of these tools tends to replica te va rious a ctions a nd mea surements tha t a re cla ssica lly done on Ea rth during field ca mpaigns. The user is therefore a ble to ta ke mea surements directly on the virtua l terra in using their ha ndhelds controllers to pla ce points on the 3D mesh. These points a re used by the VR a pplica tion to displa y a wide ra nge of mea surements such as dista nce (either on a fixed a xis or freely, Fig. 2a ) or a n- gle, but a lso to ca lcula te strike a nd dip of a surfa ce using a multi-point best-fit pla ne (Fig. 2b). Additiona lly, the use of VR provides enha nced complementa ry experience to a cla ssica l fieldwork. Aside from the fa ct that the user ca n go virtua lly a nywhere in the entire virtua l environment (including otherwise ina ccessible cliffs), we ta ke a dva ntage of the power of this visua liza tion technology to integra te GIS-like fea tures. These func- tions a re used to provide precise position, but a lso ena - ble a dva nced features like the a bility to quickly a nd ea s- ily switch the ba sema ps, e.g. from orbita l orthoima ge to geomorphologica l ma p (Fig. 2c), or to reproject a ctual origina l photogra phs ta ken by the Curiosity rover di- rectly onto the 3D terra in (Fig. 2d).

“In situ” measurements at the Kimberley out- crop: These tools a re therefore used to rea ssess the pre- viously studied but still poorly constra ined Kimberley Fm., ma de up of 4 distinct silicicla stic members (Squa re Top, Dillinger, Mt. Rema rka ble a nd Bea gle, [e.g. 7]).

Using the VR a pplica tion, we a re a ble to observe and ma p the conta cts between those members from different points of view, a nd despite the presence of widesprea d regolith a ll over the outcrop (yellow lines on Fig. 3).

With those new bottom a nd top limits, we a re using our integra ted VR tools to perform a seria lized mea surement of the thickness of the Dillinger mem ber between its lower conta ct a nd the reference bed where the Windja na drill hole wa s performed. These mea surements show the presence of a previously unseen but

1169.pdf 52nd Lunar and Planetary Science Conference 2021 (LPI Contrib. No. 2548)

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conspicuous la tera l va ria tion in the thickness of the Dil- linger member, ra nging from 55 cm in the northernmost pa rt of the outcrop a nd up to 85 cm in the southernmost pa rt (green ba rs on Fig. 3). Going further in the cha ra c- teriza tion of this interva l, we used the best-fit pla ne tool to compute the strike a nd dip of the Squa re Top/Dil- linger conta ct. This led to the cha ra cteriza tion of a ~3°

dip towa rd the south, potentia lly hinting a t the presence of a slight pa leotopogra phy a t the time of deposition.

Summary: The growing use of VR to explore and cha ra cterize pla neta ry surfa ces is a gia nt lea p towa rd a better a nd finer comprehension of their geologica l fea - tures. To tha t extent, dedica ted VR-ena bled tools integra ted within virtua l environments genera ted using both la rge-sca le orbita l a nd sma ll-sca le, high-resolution , ground-derived da ta , is key to provide a n immersive

“virtual fieldwork” experience. Using these tools, one is

ca pa ble to perform geologica l mea surements with unprecedented a ccura cy a nd with the a bility to freely observe the structures from a ny point of view, without de- forma tion, which is usua lly prevented on a tra ditional computer screen. VR therefore a llows us to propose a c- cura te mea surements of pla neta ry outcrops, lea ding to the better understa nding of the sedimenta ry processes.

Acknowledgments: EU H2020 Pla nMa p project a nd VR2Pla nets.

References: [1] McGreevy (1993) in Virtual Real- ity, 163-197. [2] Le Mouélic et a l. (2020) Remote Sens- ing, 12(11), 1900. [3] Ba rnes et a l. (2018) Earth Space, 5(7), 285-307. [4] Schneega ns et a l. (2020), Zenodo, http://doi.org/10.5281/zenodo.4288287.[5] Ma t et a l.

(2014), IOP Conf. Series: Earth and Env. Science 20, 012037. [6] Ca ra va ca, G. et a l. (2020) Planet Space Sci., 182, 104808 [7] Le Deit et al. (2016) J. Geophys. Res.

Planets, 121, 784-804.

Fig. 2 Illustra tion of severa l VR-ena bled tools usa ble in the virtua l environment on the Kimberley outcrop. a ) Dista nce mea surement; b) Best-fit pla ne computed using severa l point to ca lcula te the strike a nd dip of a given surfa ce; c) GIS- like fea ture a llowing to quickly switch between severa l ba sema ps (e.g. geomorphologic ma p, orthoima ge); d) Actua l Na vca m ima ge ta ken by Curiosity reprojected onto the 3D terra in of the virtua l environment.

Fig. 3 VR interpreted view of the Kimberley outcrop, highlighting the newly ma pped contacts between the Square Top, Dillinger a nd Mt. Rema rka ble members (yellow lines, da shed lines denota ting a hidden pa rt). Ma in thickness mea surements of the Dillinger member a re expressed by green ba rs, highlighting a la tera l va ria tion in thickness of the member. The observed southwa rd dip of the Squa re Top/Dillinger conta ct is shown in blue.

1169.pdf 52nd Lunar and Planetary Science Conference 2021 (LPI Contrib. No. 2548)