What is Structure from Motion (SFM) Photogrammetry

In this chapter a revision of the traditional tracing methods over petroglyphs through the employment of three dimensional models is proposed. The different techniques suggested here are: Radiance Scaling and Algebraic Point Set Surfaces (APSS). Radiance Scaling is a shader that adjusts reflected light intensities in a way dependent on both surface curvature and material characteristics. While APSS allows the colorization of the vertices of a mesh or point set using the curvature of the underlying surface. These methods applied to 3D models allow a better visualisation, comprehension, and objectification of the open-air rock art carvings, improving the researches over a more reliable database, but also for issues related to management and conservation.