Precolumbian Maya graffiti is challenging to document because it is complex, multilayered, and difficult to see with the naked eye. In the Maya Lowlands, precolumbian graffiti occurs as etched palimpsests on parts of substructures such as stucco walls of residences, palaces, and temples that are frequently only accessible through dark and narrow tunnel excavations. Experienced iconographers or epigraphers with advanced drawing skills are the most qualified researchers to accurately record, analyze, and interpret precolumbian Maya graffiti. Because these scholars have a vast knowledge of conventions and styles from multiple time periods and sites, they are less likely to document the complex and seemingly chaotic incisions incorrectly. But as with many specialists in Maya archaeology, iconographers and epigraphers are not always available to collaborate in the field. This raises the question, how might an archaeologist without advanced training in iconography accurately record graffiti in subterranean excavations? Advances in digital applications of archaeological field recording have opened new avenues for documenting graffiti. One of these is Reflectance Transformation Imaging (RTI), a method that uses a moving light source and photography in order to visualize, interact with, and analyze a three-dimensional object in a two-dimensional image. With practice, RTI images can easily be produced in the field and later shared with specialists for the purposes of analysis and interpretation. Performed on a series of 20 unique graffiti from the Maya archaeological site of Holtun (two examples are presented here), RTI shows promise as a viable technique for documenting and preserving graffiti as cultural heritage.

Newly discovered and previously documented Late Neolithic chalk plaques from the Stonehenge locality have been subjected to new, non-invasive techniques which allow access to previously unseen elements of archaeological evidence. The application of these methods – involving Reflectance Transformation Imaging (RTI) and Polynomial Texture Mapping (PTM) – has revealed detail of the surface preparation and allowed methods and sequence of the compositions to be unpicked, clarifying their complexities. The results reveal a range of approaches to the compositions, some of which demonstrate planning, order, and intention while others include less systematic, rapidly executed sketches. Investigations of lines and surfaces have been made, supplemented by preliminary studies of replicated test pieces, to examine potential implements used in their creation and remark on plaque biographies and surface attrition following manufacture. Furthermore, detail revealed by RTI provides indications of the orientations in which some of the plaques should be viewed and – in one instance – suggests a ‘reflected’ element that may not be entirely abstract. Results from improved radiocarbon determinations place the plaques in the early part of the 3rd millennium bc which, together with identification of individual motifs, allows the plaques and the designs to be reconsidered within the corpus of Neolithic art in the British Isles.