THE APPLICATION OF PHOTOGRAMMETRIC ORTHOMOSAICS FOR DOCUMENTATION OF PALAEONTOLOGICAL SITES

IGNACIO DÍAZ MARTÍNEZ; PAOLO CITTON; SILVINA DE VALAIS; CARLOS CÓNSOLE GONELLA; ARTURO MIGUEL HEREDIA; FACUNDO RIGUETTI; PATRICIO VILLAFAÑE

Congreso; 1st Palaeontological Virtual Congress; 2018

Fieldwork is crucial in palaeontological studies. Both when the fossils are being exposed from thesite and when they are studied in situ. Therefore, an exhaustive documentation of these remainsand their reciprocal position within the rocks are necessary for further study, includingtaphonomical, palaeoecological, and systematical analyses. For this purpose, a powerful, non-invasivemethodology, based on Structure from Motion (SfM) algorithms was used to create orthomosaicsand 3D reconstructions. Documentation of fossil features was performed through 2D photographstaken from multiple angles and with sufficient overlap and coverage. A series of individual photosmatched up to constitute a new composite image or orthomosaic , in which the geometricdistortion was corrected and orthorectified, such that the scale was uniform. The orthomosaicallowed a rapid and reliable documentation of the outcrops than conventional methods (i.e.drawings, total station). It reproduces a precise orthogonal X-Y scheme of the site and can be usedto measure true distances and surfaces. During excavations, it is advisable to generate anorthomosaic before and after the extraction of each fossil to subsequently analyze the overlappinginformation. Thus, by adding the vertical (Z) information, three-dimensional positions of all theremains can be reconstructed during the excavation works, and quite precise 3D taphonomic mapscan be obtained. The generation of photogrammetric orthomosaics turned out to be an effective,rapid and cost-effective tool for checking and correcting the relative and absolute position offossils within a site, and complementing the traditional information obtained duringpalaeontological field trips.