Abstract:

Introduction:
The bearded vulture (Gypaetus barbatus) is a large-sized bird and the most endangered scavenger species in Europe. In 2010, its population was estimated to be between 576-785 pairs, with Spain ranking third in number. In 2018, a controlled population of 126 pairs was estimated in Spain, with the provinces of Huesca and Lleida being the main breeding areas for the species. Practical sessions in the degrees of Sciences and Health Sciences are essential for students to acquire the essential skills and knowledge. In situations such as the COVID-19 pandemic, online materials are useful for students to complement practical sessions. Virtual 3D content facilitates the understanding of various experimental processes and the study of anatomy. This study proposes a model of virtual educational innovation to enable and expand the possibility of more scientists and students accessing the anatomical study of the endangered bearded vulture. We compare three different techniques for obtaining 3D digital models of its bone skeleton: structured light scanner, computed tomography (CT), and photogrammetry.

Methodology:
We performed 3D digitization and virtualization of an adult bearded vulture skull using a structured light scanner with texture (Ein Scan SP), a CT scanner (Albira ARS II PET/CT), and photogrammetry technique (Canon EOS 1DX ). After obtaining the 3D images, the resulting files with explanatory labels for each bone were uploaded to Sketchfab, compared and made accessible on the website of the Complutense University of Madrid (UCM).

Results:
The material is freely accessible and available at the following website: https://www.ucm.es/fisioanimvet/comparativa-de-tecnicas.

Discussion:
This project generates material that can be used as a complementary resource by teachers, researchers, and students at different levels. The generated material can be useful for researchers due to its applicability to different experiments and conservation studies where the bearded vulture is directly or indirectly involved. In addition, it allows for the elimination of the use of real bones to obtain knowledge of anatomical details and facilitates the possibility of comparing and identifying bone remains found in a natural setting. At the educational level, this virtual 3D content guarantees a public, long-lasting, attractive, and high-quality teaching material that can be easily transmitted, providing a comparison between different techniques. Virtualization with the structured light scanner presents the advantage of being a fast, simple, and relatively cheap technique that provides color texture, but it does not allow the obtainment of a complete image of the bone's internal structures. The CT provides information on internal structures and good image quality, but its economic cost is high and it does not generate texture. Finally, photogrammetry leads to a high-quality image and color texture, with the main drawback being the post-processing time required to obtain the 3D image and the lack of information on the bone's internal structures.

Conclusions:
The implementation of university teaching with 3D models is necessary to provide a great advance in the teaching and research field. This comparison between the three techniques allows us to determine the main benefits of each one and the possibility of complementation between them to obtain an optimal virtual model.

Keywords:

Bearded vulture, bone, skull, 3D, structured light scanner, CT, photogrammetry, educational innovation.