Abstract

GUDINO MAUSSAN, José L.; AGUILAR, Felisa J.  and  HERNANDEZ-RIVERA, René. Use of digital photogrammetry to record dinosaur footprints in the Cerro del Pueblo Formation (late Campanian), Coahuila, Mexico. Bol. Soc. Geol. Mex [online]. 2018, vol.70, n.2, pp.307-324. ISSN 1405-3322.  https://doi.org/10.18268/bsgm2018v70n2a3.

In the last decade, digital modeling techniques have been shown to be very useful in the study of fossils and their preservation, especially with ichnites (footprints) that are very difficult to collect or model by traditional methods, due to deposit characteristics such as size, heritage, touristic importance and conservation status.

In Cerro del Pueblo Formation (FCdP), a geological unit of the late Campanian, located in the southeast Coahuila, Mexico, there is a great fossil diversity, mainly dinosaur ichnites, which unfortunately have been little studied and are in danger of destruction, due to the erosion and human activities. The goal of this project was testing the effectiveness of a new and low-cost technique with no impact for the ichnites. The technique consisted of modeling by digital photogrammetry through the open access software VisualSFM, Meshlab, CloudCompare and ParaView. For this purpose, the dinosaur tracks of six different sites (deposits) in FCdP were recorded. Ten commercial quality cameras (5 to 10 Mpx) were used to take photos at each site. At smaller sites with a fewer number of footprints (Cantera Rojas, 26 m2 [4 tracks]; Depósito de la Luz, 37.5 m2 [6]; La Rosa, 60 m2 [9] and Las Águilas B, 70 m2 [12]), individual shots of ichnites were taken. Also, a complete photo series throughout the deposit was taken. Larger sites (Paso del Oso, 168 m2 [107] and Las Águilas A, 340 m2 [220]) were divided into sections to simplify the photographic record.

In total, 11840 photographs were taken, 4960 were used to generate 72 three-dimensional textured polygonal mesh models for the six localities.

Models from smaller sites had better quality because of their reduced size, the large number of photos taken and good strata contrast. In contrast, models from bigger sites lost definition, especially after certain adjustments made to improve their computer processing. During this exercise, reference parameters were obtained, to increase the effectiveness in photography for photogrammetric processing. We hope in the future to improve the quality of digital models generated.

Keywords : Dinosaur tracks; Cretaceous; registry techniques; virtual modelling.

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