Technology
Since its inception, the Pompeii Quadriporticus Project has sought to use cutting-edge technology to improve the fieldwork, analysis, interpretation, presentiaton and publication of our work. To date, the techonolgies employed have served to 1. create a digital model of the Quadriporticus, 2. efficiently record obsevations of individual segments of the architecture, and 3. peer below the ground surface in the building's large, open area.
Digital Models
Two complementary digital recording technologies are used in the Quadriporticus: 3D laser scanning and photogrammetry. In 2010, S.I.A. ingegneria e ambiente was hired to capture the open, central area, columns, internal facades and monumental stairway of the Quadriporticus. Using a Leica ScanStation C10 three dimensional laser scanner, the survey was completed on July 30, 2010 in nine stations. The scanner captured spatial information in millions of measurements at a resolution of +/- two millimeters. Compared to the standard archaeological practice (which we have employed for more than a decade in Pompeii) using a single point laser theodolite, the 3D laser scanner is a quantum leap forward.
First in partnership with AutoDesk using its 123D Catch product (and previously using itsbeta project, Photofly, 2010-2011 field seasons) and now using AgiSoft's Photoscan software (2012-2013 field seasons), we are complementing the laser scanning campaign with a photogrammetric method that is more time- and cost-effective for certain aspects of the architecture. Using approximately 40 high-anlge digital images per room, the PQP is capturing the dozens of spaces surrounding Quadriporticus and rendering them in photoreal 360˚ panoramas as well as high density pointclouds that can be integrated with the laser scanning results. Premilary results showed exceptional promise and our current work is surpasing expectations.
Digital Recording
The PQP utilizes most standard procedures for recording masonry analysis at each level of our method, capturing information about the materials, mortars, and construction techniques of each wall face. We have used the iPad, however, to make our recording process completely digital. The iPad is an ideal instrument for our project as it offers a lightweight, durable, and intuitive machine with a battery life that exceeded the length of our work day. A Filemaker Pro database on the main project computer housed the parent database and synchronized with child versions on each iPad (FileMaker Go). One of the main benefits of this system was that each team was able not only to record all the information about the wall faces that they were studying in their own iPad, but also they could (after syncing) instantly access the all the information that was gathered on another team's iPad. This was particularly useful when one wall face was in the process of being interpreted and the wall's opposite side had previously been studied and recorded. Our use of the iPad for on-site recording, drawing and analysis in 2010 found that the only major limitation was that too few iPads created a bottleneck in data entry. We addressed the problem in our 2011 season by equipping every team member with an iPad. Even after controlling for a learning curve, the increase in efficiency was dramatic: with three additional iPads, 371% more work was completed by 35% fewer people. Another benefit of this system, from a data security standpoint is that after synchronizing with the main computer and the other iPads, each machine was carrying the complete dataset, making each a backup file of all the project's data.
The process of drawing each wall face was also improved by using the iPad. Standard practice for wall drawings is to create a horizontal baseline across the width of the wall along which measurements of features (SUs) can be made above and below the line. The measurements are then plotted to scale on mylar with a graph paper template. The process requires two people and is very time consuming. Our process makes the best use of the iPad's touch screen and zooming capabilities in order to streamline the drafting of each wall face. We first take a digital photograph of each wall face - including a one meter ranging rod - and then import it into the iDraw application. The image is then traced over, drawing the location of each stratigraphic unit in its own layer. Having each stratigraphic unit in its own layer is especially useful because the different phases of construction can be shown alone or in any desired combination, illustrating what the wall or a series of walls looked like at a particular phase of the building. It is also very easy to update the drawing in the event of an error in drafting or if the interpretation of the object changes.
Further information on our use of the iPad can be found through our sister project, available from the PARPPS website as well as a pdf of the original story on apple.com.
Geoprospection
Subsurface imaging in the Quadriporticus' central area was conducted in June, 2011 by the British School at Rome and the Archaeological Prospection Service of Southampton. The Ground Penetrating RADAR (GPR) survey covered the c. 1530m2 open area in a series of 0.25m x 0.50m transects and reached an approximate depth of nearly three meters. Preliminary results of this survey can be found in our report on the 2011 Season of the Pompeii Quadriporticus Project, published by the Fasti On Line Documents & Research. (2012). A second campaign of GPR survey in 2012 was conducted along the colonnades and within a few rooms behind the colonnades. Subsurface imaging is complementing our equally non-invasive masonry anaysis by revealing the position (and, importantly, the absence) of pre-existing architectures and infrastructural elements
Together, these technologies complement one another by creating an exacting digital record of the architecture of the Quadriporticus, which serves as both a subject of analysis itself as well as acting as a digital platform to structure, preserve and access the in-field observations made about the architecture. Thus, the digital model becomes both the most recent and accurate 3D state plan and the framework onto which database information, wall drawings, and imagery (photographic and subsurface) are attached.
