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

Notes from the Field

Arriving to the city on Friday, we immediately went to the museum. We were in a hurry to gain access to Quiriguá Altar L, because the piece was set to be on loan to a museum in Toronto and would not be available after this week for our team to digitize. Using our structured light 3D scanners, our team quickly documented this stone monument, capturing all of the finely carved details and morphology of the piece.

Scanning Altar L at the National Museum in Guatemala City.
Preliminary data acquired with the Artec structured light scanner for Altar L – curated at the National Museum in Guatemala City. These data will be brought together with texture information for a finalized version of this sculpture.

Saturday was spent driving out of Guatemala City arriving at Quiriguá in the afternoon. After getting settled into our accommodations, the DHHC team did a brief tour of the site before sundown. Sunday morning began our first day of scanning and working at the site, and we spent much of the day with reconnaissance, planning, and gathering initial data. Oswaldo Gomez, the Director of the Quiriguá site, is our collaborator on this project, and is serving as a co-Principal investigator. He has organized a team from Guatemala that is helping with logistics and site preparation- including some clearing of vegetation, revealing portions of the site not in decades. The Guatemalan crew is helping our team with assembling shade tarps and providing the scaffolding that are imperative for best documentation using the structured light 3D scanning instruments for the documentation of monuments. 

The Guatemalan archaeology field crew assists in site preparation and documentation needs for the project. Installation of tarps around the stone monuments is providing consistency in lighting for our specialized imaging and 3D laser scanning.
The USF DHHC field team includes 3D Specialists Jorge Gonzalez and Noelia Garcia, archaeologist Jaime Rogers, Director Travis Doering, and drone pilot and photographer Garrett Speed. 

Data acquisition with our structured light scanners on this first day, included work at the ornately carved Stela A. Because we have multiple scanners, we were able to simultaneously work across different areas of the site, and complete the sub-millimetric digitization one of the more challenging carvings in the round – Zoomorph O – and the associated Altar O. Data from these monuments will be post processed and include texture mapped images and color detail. We will next move to Stela C, Zoomorph P, and Altar P, as part of our prioritization of sculpture documentation. 

3D Specialist, Noelia Garcia, using a structured light scanner to capture glyphic text, iconography, and morphology of Zoomorph O. 

We have also begun to 3D map the terrain features at Quiriguá using terrestrial LiDAR instruments, including a phase shift FARO Focus scanner, and the new hybrid Time of Flight scanner from Leica – the RTC360. We are combining our ground-based survey efforts with structure from motion photogrammetry techniques (SfM) that use a drone- based platform for acquisition. We are also using GPS to establish ground control. Our drone-based survey so far has included extended periods of pre-programed flights for the coverage of the core area and including an extension into the surrounding environs.

Project Director, Dr. Travis Doering, shown using terrestrial LiDAR to document terrain and structural features at Quiriguá.
DHHC archaeologist, Jaime Rogers, working with the Leica terrestrial laser scanner in the plaza area.
USF’s Garrett Speed uses GPS to mark control points used for the drone-based survey, as well as for mapping features and locales of importance at the site.
3D Specialist, Jorge Gonzalez works with structured light scanning to 3D document one of the enormous carved stone stela from the site of Quiriguá.

This project involves extensive public interaction and outreach, and our in-country project logistics cooperator, Felipe Guzman, has been indispensable in helping promote the project to the visitors. Guzman has also been assisting with communications and partnership development. The project success is owed largely to our connections through Felipe and we are grateful for his friendship, interest, and love of archaeology. 

Felipe Guzman, our in-Country logistics supporter, watches as 3D Specialist Noelia Garcia works to 3D document one of the large, fragmented zoomorph carvings.
The team during reconnaissance planning at the site.