From Light to Virtual: Comparing RTI and VRTI for Ichnological Analysis

Reflectance Transformation Imaging (RTI) has long been employed across multiple research domains to document surface textures, inscriptions, and fine morphological features, including paleontology. However, RTI requires specialized equipment and controlled acquisition protocols that are often impractical in fieldwork or heterogeneous documentation contexts. To overcome these limitations, Virtual Reflectance Transformation Imaging (VRTI), based on high-resolution 3D models acquired through photogrammetry or structured-light scanning, has emerged as a promising alternative. This study investigates whether VRTI offers an operationally simpler yet perceptually consistent alternative to conventional RTI for dinosaur footprint interpretation, while providing a standardized FAIR-compliant VRTI workspace implemented in an open-source 3D environment. A comparative protocol was developed and validated through a classroom experiment involving paleobiology students, who performed footprint delineation and morphological interpretation using both RTI and VRTI datasets derived from a dinosaur footprint from the Geological Collection of the "Giovanni Capellini Museum" of the University of Bologna. The evaluation combines quantitative statistical analysis with qualitative expert assessment to compare interpretative performance, while optimal PTM-based raking-light conditions are also investigated. The results of the statistical comparison between RTI and VRTI remained non-significant (p > 0.05) for the tasks involved in the experiment, indicating comparable interpretative performance between the two approaches. Building on this validation, a preliminary usability assessment of the proposed workspace (n = 11) yielded a mean System Usability Scale (SUS) score of 67.7, supporting its practical applicability while providing a reproducible, interoperable, and scalable workflow for cultural heritage documentation.