ROCK ART RECORDING IN KHATM AL MELAHA (UNITED ARAB EMIRATES): MULTIRANGE DATA SCANNING AND WEB MAPPING TECHNOLOGIES

: The application of geometric recording data and representation of open-air rock art is intrinsically so heterogeneous that new online web platforms are required for a more efficient analysis to link all the geo-referenced information and facilitate its scientific study. From 2015 to 2018, three geometric documentation campaigns led by the Departamento de Ingeniería Topográfica y Cartografía of the Universidad Politécnica de Madrid (Spain) were completed in the area of Khatm al Melaha (Emirate of Sharjah, United Arab Emirates) along the Gulf of Oman. More than 370 rock art engraved motifs were documented in this area close to the southwest border with the Sultanate of Oman. All those figures were picked in 149 stone blocks with different dimensions and morphologies, distributed along the slope of an isolated 58-meter-high elevation. The aim of this project was to establish a protocol for the recording, analysis, preservation and prevention of this set of open-air rock art engravings with the following actions: developing an aerial and terrestrial recording data documentation, creating and developing a web platform called threeDcloud for visualizing three-dimensional models and web mapping, and integrating a data base by means of different JavaScript open-source libraries.


INTRODUCTION
In this paper we propose a primary methodology procedure that allows integrating into web access of data recorded from the archaeological area of Khatm al Melaha (Emirate of Sharjah, United Arab Emirates), combining different geomatic techniques at different scales from a broad yet technical perspective.In order to improve scientific analysis, the documenting process should always consider every aspect of recording as well as preventive control, conservation and interpretation.Along these lines, some open-access, web-based 2D and 3D JavaScript libraries have been created to unify, simplify and analyse their different uses through a web platform called threeDcloud.The use of new technologies for recording and identifying openair rock art in nature is so diverse and the techniques applied are often so complex that they hinder interdisciplinary understanding, failing to provide a standardised methodology.New development techniques are hence needed.Procedures should be standardised to provide scientific analysis, as well as dissemination and understanding of the generated data and its possibilities.Three geometric surveys were carried out between 2015 and 2018 in the archaeological area of Khatm al Melaha (Emirate of Sharjah, United Arab Emirates) along the Gulf of Oman, led by the Departamento de Ingeniería Topográfica y Cartografía, Universidad Politécnica de Madrid (Spain).More than 370 rock art engravings were documented in this area close to the southwestern border with the Sultanate of Oman (Figure 1).The engravings were carved on 149 stone blocks of different dimensions and morphologies spread along a 58-meter high isolated slope (Figure 2).Some of those decorated boulders are in secondary condition, having rolled down the hill (natural degradation processes) or having been used for some of the modern human structures documented in the area (Figure 1. A).Despite the high concentration of rock art panels, associated archaeological finds were scarce: only two small undecorated handmade pottery fragments, a couple of flint flakes, and a hand mill fragment were found in an examination of the surface area.In order to understand this rock art concentration from a visual perspective, in its location it's easy to see the N-S communication route parallel to the Gulf of Oman, as well as the E-W route to the interior through the Wadi al-Hilu, currently connected by the Sharjah-Kalba highway (Jasim et al., 2016).Apart from those artefacts, a large shell midden was found at the foot of the hill facing East, and some circular structures (in varying conditions) mainly along the Eastern side of the slope but also at the top of the elevation and on the western side.Even though they haven't yet been defined as funeral graves, some other nearby rock art areas have, as it is the case of Fujairah (Ziolkowski, 1998(Ziolkowski, , 2007;;Ziolkowski and Hassan, 2000).Despite being in its preliminary phase, the project has so far seen the following achievements: 1) The creation of a wide catalogue of documentation with strong possibilities of dissemination, such as a 2D and 3D online repository data.
2) The integration into web access of interrelated models at different scales.
3) The integ control, conser    were edited with Photoshop, using several tools such as Magic Wand, Lace Tool and Colour Range Command, depending on the specific needs of each area of the image.Those pixels that do not correspond with the engraved area are eliminated, and the image is isolated in a particular layer to show the rock art engraving separated from its physical support.Additionally, a copy of the original image is created with lowered opacity in layer.The tracing previously created is superimposed onto this image, thus highlighting the engraving while presenting visual information about the physical support in which it was created (Figures 7.3 and 7.5).There are multiple possibilities of quickly modifying the tracing once obtained, being a versatile method that allows for a variety of results depending on the needs (Figures 7.4 and 7.5).Alternatively, other automatized systems such as Meshlab and DStretch were tested on the 3D model texture highlighting the latter (Figure 6).

ABOUT OPEN-AIR ROCK ART: CONNECTIONS BETWEEN ROCK ART AND LANDSCAPE TOPOGRAPHY
Even though there are some studies relating to rock-art in Arabia (Anati, 1968a(Anati, , 1968b(Anati, , 1968c(Anati, , 1972(Anati, , 1974;;Bednarik andKhan, 2005, 2017;2007, 2013;Newton and Zarins, 2000), those located in the United Arab Emirates are less numerous (Ziolkowski, 1998(Ziolkowski, , 2007;;Ziolkowski and Hassan, 2000).Despite being in its preliminary stage, this project has an inductive approach that goes from the particular to the general, classifying the rock-art motifs according to a distinctive classification in order to compare it to those from other areas.Therefore, in this initial phase of the project, we have tried to classify the documented study at Khatm al Melaha according to four different parameters: style, technique, topic and colour of the patina, all of them concerning the particularities of the region.

Style
Ascribing a specific artistic style to one culture or historical period seems a rather confusing task.In the debate about the appropriateness of the term "art" for graphic prehistoric representations, the discussion about the concept "style" has some interest.The idea of style appears somewhat confusing for archaeologists and pre-historians, being "one of the most difficult concepts in the lexicon of art and one of the chief areas of debate in Aesthetics and Art History" (Turner, 1996).Nevertheless, we consider that this term is essential for interpretation as well as for many other fields, such as art history, social studies, etc. Understanding the term as a coherent system of qualities in a certain period, it is also worth highlighting that, for prehistoric rock-art, the term should refer to a wider social group and not to an individual personality.
As we see it, rock-art studies should look into a way of examining the morphological variations of representations to see what type of results about prehistoric societies would a stylistic analysis render.We should inquire what type of formal variables constitute a specific style and try to define the status of the cultural, social and material processes that circumscribe it and materialize it as a cultural characteristic (Roe, 1995: 27).The challenge is to set those goals that let us single out groups of attributes that can be used to identify certain processes from the past (Carr and Neitzel, 1995).We should understand style not only as a means of doing something but rather as the representation of an idea, since the term surpasses its technical specifications.
Since the end of 20th century some debates have taken place about the idea of style in archaeology, its main line being the discussion about the following questions: how should conceptual style be differentiated?How should function and technology be distinguished in operational contexts?Which factors determine a style?How important is the context in determining a style?What characteristics of a given style are more or less important when reconstructing processes from the past as well as ancient conditions and social units?(Carr and Neitzel, 1995: 6).
To our view, the main line of the debate should focus in establishing those attributes that better differentiate a group of given representations so as to recognize those elements, qualities, proprieties and particularities that delimit a "style".A number of questions then arouse.Would it be possible to isolate a given number of attributes and compare them, in order to interpret their ideological meaning through the contextual associations in the archaeological language?Do the structural aspects of a style always indicate a specific ethnic or cultural group, or can those aspects only reflect a wide range of social groups?By delimiting stylistic spans in our field we will realise the existence of ethnic regions that have their own characteristics in different levels (the form of the representations, the connection among them, the artistic topic, the archaeological and cultural context, dates, etc.).We hope that the understanding of these regions will help contribute to the general context of rock-art in the Arabic Peninsula, its origin and evolution with consistency in both time and space.
From more traditional views-mostly historicist-the term "style" has been defined in material and contextual terms that are obviously more appropriate for historicist epistemology.Once those parameters were overcome, and perhaps as a reaction to subsequent postulates such as those of the New Archaeology, at the end of the 20th century more modern views appeared.These views understood the debate about the terminology from a rather theoretical perspective, by which styles are seen as an active expression directed to obtaining meaning as much as cultures and social groups are, too.They vary depending on both the context and the historical moment, and all of them highlight certain restrictions that determine each style as a process, whether this is material, economical, social, ecological... (Conkey, Soffer, 1997;Hodder, 1990).This line has been followed by other researchers who understand "style" as an intentional, structured system of selecting certain dimensions of form, process or principle, function, significance, and affect from among known, alternative possibilities to create pleasing variability within a behavioral-artifactual corpus (Roe, 1995: 31).Indeed, "art is a very difficult word to use successfully" and "the use of art as a descriptive term in relation to petroglyphs, engravings, carvings, etc. is fraught with confusion and subjectivity" (Ziolkowski, 1998: 23).It is for this reason that we use the term "style" with caution even though we believe it should not be forgotten (Clegg, 1993: 102).Along these lines, considering our observations in our small area of study we have established four different styles, two of which also have specific characteristics that classify in two substyles.According to the morphological characteristics of the engravings, these would be classified as follows: 1. Schematic; 2.1.Synthetic, 2.1.Synthetic hypertrophied; 3.1.Stylised, 3.2.Stylised hypertrophied; 4. Abstract or Symbolic.
This project aims to establish connections between the stylistic phases mentioned and those that have been noted in former studies with a time-cultural value: Islamic, literate, herding and hunting, early hunters (Anati, 1968a(Anati, , 1968b(Anati, , 1968c(Anati, , 1972, Figure 3. mapping linke aerial and ter immersive vie texture do

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