When It Rains It Pours!

Field update – for several days we had light to no rain, coming only for short periods in the afternoon, but then we really got RAIN!!! For about 4 hours straight we had consistent downpours. Fortunately, our 3D Specialists working on the monument documentation (Jorge Gonzalez and Noelia Garcia) could continue scanning inside the tented structures. This did not work for the rest of the team working on landscape documentation (GPS, drone PhoDAR, imaging, and terrestrial laser scanning).

Palapa roof structures that are used to cover the carved monuments – we have now enclosed with tarps to minimize light impacts during structured light scanning. Ambient light can interfere with the effectiveness of the scanners and cause noise and problems with data acquisition. Our team, working with the Guatemalan resource management team, erected tarps around each area that we worked at with sensitive instruments.

Led by Oswaldo Gomez, the Director of the Quiriguá site, some of our team visited Group A, located about 5 kilometers northwest of the site. Prior to coming into the field, the USF DHHC GIS Analysts created a geodatabase, referencing the modern landscape to historic maps and site plans from more recent archaeological investigations, all the way back to the early maps and site plans from Alfred Percival Maudslay’s time. Using these maps in the background on our GPS units, we are able to walk to areas of interest, and relate locations of features previously encountered to the terrain we see today.

Plan of the ruins at Quiriguá (Maudslay, Alfred Percival. 1889. Biologia Centrali-Americana)

We were met by Carlos Obdulio Aldana Aldana, the owner of the property that contains Group A, and he graciously allowed us access. Group A sits high above the valley and provides fantastic views of the Motagua River, the banana plantations, the Village of Quiriguá and the archaeological site. Field methods in this area included panorama and gigapixel imaging and drone-based photogrammetric detection and ranging (PhoDAR). The PhoDAR mapping allows us to acquire detailed terrain 3D models as well as ortho-photography when combined with ground-based control targets.

Terrain documentation work in the surrounding environs of Quiriguá

The heavy rains came quickly during our work in this area, and we were forced to stop and protect our gear. We walked back through heavy rain to Senor Obdukio’s farmhouse to breakdown and pack the equipment. On the way back, we stopped at a tienda to by six pounds of rice (dried grains such as rice absorb liquids, so this proved to be a readily available means of drying out our devices- including cell phones). Very useful hack that proved effective!

Phone covered in rice to absorb moisture – a hack that works!

Meanwhile, back at the Acropolis and Great Plaza, painstaking high resolution scanning with the structured light instruments continues. Much time is required for the staging (assembling tarps and scaffolding to reach and access all parts of these large monuments), and there is much difficulty in reaching and maintaining parallel scanning position across the face of the zoomorphs. Our team used not only scaffolding, but also worked with booms and pole extensions to completely document the carvings. Our highest resolution instruments (0.25 mm) were used on faint or areas of finer detail. This highest resolution scanning is time consuming, sacrificing scale/coverage speed for accuracy.

Working with a fiber carbon monopod with the structured light scanner to maintain parallel position and cover the entire surface of the complex and large zoomorph monument.
Working with the high resolution structured light instrument to capture fine details and faint or diminished glyph areas. Note that Noelia prepared for awkward positions and bending- packing kneepads that have definitely come in handy and kept her more comfortable during this hard work.

No Rain Meets Hot!

March 19, 2019 post – No rain today, but a heat has definitely returned. Our team continued with the terrestrial laser scanning survey in the site Acropolis and southwest portion of the Great Plaza today. Our newest TLS bit of kit is the Leica RTC360 scanner- which is definitely giving us speed, agility, and accuracy capacity and is integrated with an iPAD interface that allows for visualization of the data in real time – an added bonus when doing public archaeology and sharing results with visiting collaborators.

Today, our friend and in-country collaborator Felipe Guzmán returns, and brings Carlos Toriello Herrerías with the Fundación Herencia Cultural Guatemalteca. Carlos is assisting with drone use coordination and has been instrumental in providing support and guidance for the project from its inception.

Drone imagery from survey of the Acropolis area

Carved glyphs at Quirigua

Field Work Continues

Light rain in the morning with brief showers just before noon seems to be the weather pattern. Our team has been working with short, mid and long range terrestrial laser scanners, with today including about 7 hours of scanning time. We are working with three TLS instruments for landscape documentation (FARO and Leica), and are using five Artec structured light scanners- capturing variable resolutions. On this project we are using 2 EVA scanners, 2 spider (close range) scanners, and 1 LEO – the newest tool in our scanning arsenal. The multiple TLS units are allowing our group to coordinate and work across areas to capture the entirety of the terrain. We are also utilizing centimeter grade GPS for spatial control and mapping, and are using a suite of imaging and drone and tripod-based reality capture and mapping strategies.

Our close range scanning include not only work on the monuments and zoomorphs at the site, but also objects from the site museum and bodega storage areas.

The efforts to clear away vegetation prior to our team’s arrival have proven to be immensely helpful, revealing the site in ways not seen since Sharer’s archaeological work at the site in the 1970s.

DHHC Archaeologist, Jaime Rogers using GPS to map areas of architectural remains.
DHHC 3D Specialists, Jorge Gonzalez and Noelia Garcia working together to capture difficult to scan portions of a large zoomorph carved culture at the site.
DHHC Photographer, Garrett Speed, is set-up to take gigapixel images across the surface of the carvings to reveal high resolution details.