# Improved Application of Hyperspectral Analysis to Rock Art Panels from El Castillo Cave (Spain)
###### Abstract  
Rock art is one of the most fragile and relevant cultural phenomena in world history, carried out in shelters or the walls and ceilings of caves with mineral and organic substances. The fact it has been preserved until now can be considered as fortunate since both anthropogenic and natural factors can cause its disappearance or deterioration. This is the reason why rock art needs special conservation and protection measures. The emergence of digital technologies has made a wide range of tools and programs available to the community for a more comprehensive documentation of rock art in both 2D and 3D. This paper shows a workflow that makes use of visible and near-infrared hyperspectral technology to manage, monitor and preserve this appreciated cultural heritage. Hyperspectral imaging is proven to be an efficient tool for the recognition of figures, coloring matter, and state of conservation of such valuable art. hyperspectral imaging; rock art; geomatics; cultural management; data processing; mapping; cultural heritage +
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cal hazards, like bacteria, fungi, lichens, and algae, can alter the delicate balance of these ecosystems whose response to human action is often unpredictable. [1]. The importance given, within speleology, to geomatics (although traditionally given only to topography), is that any study subsequent to the discovery of a cave needs a map of the cave on which to base the study. Hence, the topographic survey is one of the first tasks to be carried out. The geomatics sciences of terrain representation are the first auxiliary techniques of speleology, since they are the fundamental basis on which all subsequent information of any multidisciplinary study is integrated. This is the reason why it is very important to have a good cartographic base that allows turning over any study carried out, and to turn over any future information that allows monitoring these living elements. The reproduction of rock art has been a recurring theme since the end of the 19 th century. For over a century, casts and photographs have been the main tool for demonstrating the existence of rock art, for facilitating its study, management, and dissemination, or for analyzing and evaluating its state of conservation. In the last few years, systems have evolved and digital tools, such as virtual reality [2], are used for tourist exploitation. Today, the emergence of digital technologies has made a wide range of tools and software available to the community to obtain more exhaustive documentation in both 2D and 3D. The exhaustive, comprehensive and non-invasive documentation of rock art sets is an indispensable requirement to carry out continuous monitoring of the processes of degradation and alteration of these sets and to guarantee the survival of this heritage. Any aspect of rock art research requires, as a starting point, the obtaining of objective graphic documentation that allows the exhaustive studying of motifs, themes, and the patterns of composition, addition and superimposition [3], etc. This work implements a methodology that offers a global, comprehensive, synoptic and, if required, repetitive vision of rock art. It consists of a non-destructive observation that can be carried out at different scales in a homogeneous way, making it possible to obtain information about non-visible regions of the electromagnetic spectrum. It has been produced in the context of doctoral activities [3; 4] and can be applied to any rock art panel or any industrial or cultural heritage with similar characteristics. Hyperspectral remote sensing and its methods are continuously growing and new applications and analyses [5] are appearing. The technique has been used for documenting paintings [6], murals [7], pigments [8], and geologic composition [9]. It presents some advantages [10] and can be used in some new possible scenarios [11]. Hyperspectral images are non-destructive and contactless, which makes it possible to use them in the study of artefacts [12] and general conservation [13].