Preserving colour fidelity in photogrammetry—an empirically grounded study and workflow for cultural heritage preservation

Abstract

In this paper, a study is performed in order to achieve a process that successfully respects the colour integrity of photogrammetry models of cultural heritage pieces. As a crucial characteristic of cultural heritage documentation, the colour of the pieces—as a valuable source of information—needs to be properly handled and preserved, since digital tools may induce variations in its values, or lose them to a degree. Different conditions for image acquisition schemes, RGB value calculation, calibration and photogrammetry have been combined and the results measured, so the adequate procedure is found. Control over all colour transformations is enforced, with blending operations during the texture generation process being the only unpredictable step in the pipeline. It is demonstrated that an excellent degree of colour information preservation can be achieved when applying said control on the factors of acquisition and colour digitalization, inclusive deciding their parameters. This paper aims to serve as guidelines of a correct handling of colour information and workflow so cultural heritage documentation can be performed with the highest degree of colour fidelity, covering the gap of non-existing standard procedure or conditions to perform an optimum digital cultural heritage colour modelling.