Some sets of prehistoric parietal engravings are palimpsests, making the analysis of their motifs complex and difficult. This is partially due to the loss of color information from each successive engraving over time, by removing the patina from the surface. In this sense, engravings also behaved like color lines. Unfortunately, the aging of these features may have made the tone of the surface rather homogeneous, only preserving the geometric information of the engraving grooves. When documenting prehistoric engravings, graphic solutions based on light and shadow relationships are insufficient. Hence, we need to find strategies that permit us to characterize more efficiently engraving groove families. The purpose of this project is, therefore, to distinguish different geometries of strokes (i.e. morphology, depth, length, width) in order to attempt to isolate the motifs and determine possible types of engraving tools. In this vein, it seemed interesting to take the sets of engravings in El Mirón Cave - a site that has been excavated by González-Morales and Straus since 1996 - as an extraordinary test case for the application of 3D scanning. The subject consists of an accumulation of linear engravings on a large block that had fallen from the cave ceiling atop a Lower Magdalenian cultural layer and then was covered by later Magdalenian archaeological deposits, all of which are radiocarbon dated, facts which has allowed dating of the engravings between 16000 BP and 13000 BP. The collection of 3D digital data was done with a structured light scanner. We used different fields of view (FOV) at resolutions ranging from 50 µm to 280 µm, to test the required level of detail to be used also in other similar engravings. We present here a few strategies based on semi-automated curvature extraction and other volume issues.
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