Rock art as microtopography

Abstract

Structure from motion (SfM) photogrammetry and geographic information system (GIS) tools were used to document an engraving site in Bontoc, Philippines. The natural discolorations of the rock obfuscated the engravings rendering traditional recording methods ineffective. Using a GIS software not only highlighted the engravings by applying an algorithm, but also allowed for a pioneering way to digitally trace and classify motifs, resulting in a spatially linked database. The digital tracings were also compared with manual tracings and proved to be more accurate. The database was then quantitatively analyzed for the seminal inventory of the rock art of Alab, Bontoc. This combination of SfM photogrammetry and GIS tools introduces a cost‐efficient method to effectively enhance, document, and analyze engraved rock art.

A review of Philippine rock art and its regional context

“…The Alab petroglyphs are very difficult to see due to the discoloration of the rock caused by erosion and biological growths. Jalandoni & Kottermair (2018), developed a low‐cost method of enhancing the Alab engravings using photogrammetry and spatial algorithms. This method was also used to enhance the Angono figures (Jalandoni & Taçon, 2018).…”

“…This paper gives a summary of my research on Philippine rock art (for further details see Jalandoni, 2018; Jalandoni & Faylona, 2018; Jalandoni & Kottermair, 2018; Jalandoni & Taçon, 2018; Jalandoni et al., 2021a). The intention is not to repeat the information already published, but to provide an overview of Philippine rock art with an outline of site management and conservation concerns included.…”

A Systematic Quantitative Literature Review of Southeast Asian and Micronesian Rock Art

“…Perhaps other sites will be found in the Philippines that could be classified as Austronesian Painting Tradition or Austronesian Engraving Style, but at present, those theories do not apply to Philippine rock art. Furthermore, the dominance of vulva forms in the known engraved sites in the Philippines and their relative absence in the rest of Southeast Asia and Micronesia suggest a local evolution for a universal motif (Jalandoni 2018). Alternatively, there is also evidence of temporal and regional rock art traditions across Southeast Asia, as proposed by Taçon and colleagues (2014), and that is supported by the similarities in some rock art styles found in the Philippines and elsewhere in Southeast Asia.…”

“…Scott and Tan (2016) provided a general update on the rock-art research for Southeast Asia. In-depth discussion on the rock art of specific locations is best found in PhD dissertations that go into detail on mainland Southeast Asia (see Taha 2000; Tan 2014a), Borneo (see Hoerman 2016), and the Philippines (see Jalandoni 2018) and books on West Papua and Indonesia (see Arifin and Delanghe 2004; Permana 2015). The seminal summary of Micronesian rock art is found in Jalandoni (2018).…”

“…Rock art has been an unexploited archaeological resource for understanding Austronesian migration until the recent efforts of Hoerman (2016), Jalandoni (2018), O'Connor (2015), O'Connor and colleagues (2018), and Tan (2016a). Tan (2016a) outlined the geographic boundaries of the rock art theories about Austronesian migration, and Hoerman (2016) and O'Connor (2015) tested the validity of the two rock art theories that relate to Austronesians in discrete Southeast Asian contexts.…”