Remote Inventory of Greek Vernacular Architecture: Online Capture of Spatial Information

Web-Based Spatial Data Management 1

Todd Brenningmeyer – Frederick A. Cooper

Abstract: Since 1990, the Minnesota Archaeological Researches in the Western Peloponnese (MARWP) has undertaken archaeological investigations throughout the southern and western edge of the Peloponnese of Greece. One of the focuses of this work, termed the Morea Project, involved a survey of vernacular architecture dating from the period of Frankish occupation in the 13th century AD to the present. This project’s goal was to discover, document, and study previously unrecorded buildings and towns before they are destroyed by man and nature. In 2004, MARWP began development of an online GIS to speed the distribution of data collected during the course of the project. Tools for the remote collection of new attribute and spatial inforation were developed as part of this application. This paper presents the process and results of the development of MARWP’s online GIS system.

Introduction traditional and innovative survey methodologies. MARWP field crews identified structures of interest In 1990, the Minnesota Archaeological Researches through terrestrial survey and remote site prospec- in the Western Peloponnese (MARWP) began three tion, in some cases using multispectral imagery to separate but concurrent archaeological investiga- pinpoint probable sites hidden on remote mountain- tions in the Western Peloponnese of Greece: the sides (Brenningmeyer / Cooper / Verfenstein 1998; Pylos, Messene and Morea projects. Together, these Cooper 2002, 26–28). Sites and individual structures projects spanned a large geographic area (Fig. 1) were catalogued in the field, surveyed with Trimble and a broad chronological range, extending from Pathfinder GPS rovers and entered into the project’s the Bronze Age through the Modern periods. The database system. Each record included detailed in- Pylos project involved the re-excavation and ex- formation that uniquely described a building’s ar- amination of architecture and finds from the Bronze chitectural characteristics. Lintels (Fig. 2) were cata- Age palace of Nestor, located in the southwest Pelo- logued with stylistic characteristics and decorative ponnese (Cooper forthcoming). A second project, details noted. Quoins likewise were examined and undertaken at the site of ancient Messene, involved characterized by type with the placement of unu- the excavation and inventory of material associ- sual decorative elements (Fig. 3) similarly noted. ated with a temple-like building that formed part Date stones (Fig. 4) were catalogued to determine of the stadium complex. The third project and the the date of construction or structural renovation. focus of this paper was the Morea project, a survey Taken together, the information collected for each of vernacular architecture in the northwest Pelo- building’s façade served as a signature for not only ponnese from the period of Frankish occupation in the building but also those involved in its construc- the 13th century A.D. to the present. This project’s tion. As F.A. Cooper has noted, “itinerant masons goal was to discover, document and study previ- brought to the construction site their own, pre-fash- ously unrecorded buildings and towns before they ioned centering systems for installation of relieving are destroyed by human activity and environmental arches above doors and windows” (Cooper 2002, processes. 41). Lintels, door casements and quoins thereby con- form to the mason’s individual style. The detailed architectural data compiled by MARWP research- Survey Methodology ers provided information about the geographic distribution of masonry styles and the movement of The Morea project was conceived as an intensive itinerant craftsmen across the countryside, which census of vernacular architecture and the survey’s continues to be a topic of interest to members of the broad geographic extent encouraged the use of both project. 2 Layers of Perception – CAA 2007

Fig. 1. Map of the Peloponnese showing the three MARWP project areas (Courtesy Minnesota Archaeological Re- searches in the Western Peloponnese).

Architectural details were collected using stand- Much of the material catalogued in the course ardized field sheets like that illustrated in Fig. 5. of MARWP’s investigations was published in 2002. Roof shape, tile type, quoin and lintel configuration The published text provided coordinates, illustra- were captured along with information pertaining to tions and descriptions of features identified during the date and history of the structure. Scaled draw- the project. However, not all of the buildings and ings and photographs accompanied the field sheets information collected during the project could be in- providing a hard copy source of data for more than cluded in the final manuscript. A significant portion 2,500 buildings. The standardized format enabled of the compiled spatial and attribute data remained the efficient translation of field notes to coded- da unpublished in the MARWP archives and data- tabase entries. base. From the early stages of the project, AutoCAD was used as both a drafting aid and repository for all geographic data. Site locations collected dur- Development of MARWP’s ing the Morea project were compiled in the project Online GIS System database and illustrated graphically within Au- toCAD. UTM coordinates marking building cor- In 2004, a decision was made to provide access to ners and roads (Fig. 6) also were collected with the complete corpus of materials in the project ar- Trimble Pathfinder rovers and downloaded into chive. Given the geographic nature of the data and AutoCAD. These points were later converted to our interest in making the material available to points, lines and polygons and form the core of MARWP researchers and other interested scholars the project’s GIS database. CAD templates also dispersed throughout the globe, an internet based were used to speed the illustration of building fa- GIS solution seemed appropriate. The intent was to cades. Many of the inked drawings created during provide a forum for both data delivery and analy- the course of the survey and later incorporated sis. The development of the MARWP GIS had spe- into the project publication were based on these cific goals from its inception. While it was- impor templates. tant to distribute our data to interested scholars we Web-Based Spatial Data Management 3

Fig. 2. Decorative Lintel (Courtesy Minnesota Archaeo- Fig. 3. Quoin catalogued in the Morea survey (Courtesy logical Researches in the Western Peloponnese). Minnesota Archaeological Researches in the Western Peloponnese). also saw the project as an opportunity to develop a or developers to use and continue development of system that could serve as a template for other ar- the application. chaeological investigations. Ideally, this template could be used by SHPO or other researchers with Phase I: Initial Development and Implementation comparable needs. Since MARWP’s research was ongoing, we also felt that it was important to pro- Version I of the Morea GIS was developed using vide colleagues with the ability to capture and at- the University of Minnesota’s MapServer applica- tribute new sites from remote locations. Rather than tion with a simple JavaScript interface managing a static catalogue for data display and retrieval, the interaction between the user and the web based the system was designed with data capture tools application (Fig. 7). This approach met many but that would allow scholars to quickly digitize fea- not all of the needs of our project. MapServer is an tures onscreen with associated attributes entered OpenSource internet map server that provides web through standardized web forms. The goal was to based access to geospatial data. GIS data, stored on create a flexible system for remote data capture as a remote server, is rendered according to parame- well as display where project members in the field ters set by the developers within a single or series could upload new data and make this immediately of text files (termed mapfiles within the MapServer available to colleagues working in remote or offsite application). These rendered images are then em- locations. bedded within the project’s web pages and served Equipment constraints encouraged the main- to the user through a web server. We were drawn to tenance of a small and efficient site profile. The MapServer because of the cost and its performance original site, launched in January 2005 relied on when tested against other proprietary systems. MARWP’s old but faithful workhorse server, which As mentioned above, much of our geographic was built from parts acquired in the mid-late 1990’s: data was held in AutoCAD. In the early stages of pentinum II 233 processor, less than 500 mb RAM, the project, AutoCAD provided one of the few plat- 5 Gb hard drive, running Redhat Linux. This server forms that supported the quick and relatively sim- proved a good testing ground as any inefficiencies ple download of GPS data to a graphical format. in our code were immediately apparent in the site’s AutoCAD also avoided some of the issues associ- performance. As with most archaeological projects, ated with coordinate precision and rounding that cost was an important consideration and a conscious were found in other early file formats. These CAD decision was made to develop the site using Open- files, however, were not directly connected with the Source (free) software. Selecting OpenSource - soft attributes that described each location and it took ware served two purposes. First, it provided a way some effort to clean and convert this data to a for- to minimize our investment in the development of mat that could be used by MapServer. We converted the application but even more importantly we be- the CAD data to shapefile format using a combina- lieved that it would encourage interested scholars tion of AutoCAD built in conversion utilities and 4 Layers of Perception – CAA 2007

Fig. 4. Date stone (Courtesy Minnesota Archaeological Researches in the Western Peloponnese).

Safe Software’s Feature Manipulation Engine (FME) which gave us complete control over the conversion process. House corner points were converted to polygons that maintained the orientation specified by either the GPS coordinates or the project database. Flat files in dbase format held the full range of attributes associated with each house, village or Frankish period site. While shapefiles are a ubiquitous file format and are supported by most GIS based applications in- Fig. 5. Standard MARWP field sheet (Courtesy Minnesota cluding MapServer, we did encounter some per- Archaeological Researches in the Western Peloponnese). formance issues and database related constraints. There were limited options for updating the shapefiles remotely. While it was possible to develop an approach that used the shapelib library (http:// Phase II: Developing an Effective Open- shapelib.maptools.org/) to remotely write or update Source Data Collection and Retrieval System the files, this was beyond the scope of our project. The dbase format also posed some problems in our We took the lessons learned during the first phase of initial design. Our shapefiles held data associated development and redesigned our interface early in with each structure in a large flat file that caused 2005 to better meet the goals set out at the project’s problems for our PHP based parser, which could inception. The second version of the Morea GIS only handle a limited number of columns within a used a combination of JavaScript, PHP/Mapscript file. and PostGIS, a spatial database extension that sits Finally, from the perspective of site design and on top of PostgreSQL, an opensource relational da- usability, the initial design of our internet GIS did tabase system (http://www.postgresql.org/) (Fig. 8). not meet the needs of our project plan. Query re- This involved some significant rewrites to the site sults were extracted directly from the database and but provided options and additional functionality fed to a small window on the left side of the web that was not possible with the original JavaScript in- page. Users were forced to scroll through more than terface. The shapefiles used in the previous version 70 columns of returned results. Worse yet, the cod- of the site were imported to PostGIS and indexed to ed records were incomprehensible to all but those improve performance. This enhanced not only our project members involved in the database design access to the database tables and individual records or GIS implementation. A scholar wishing to exam- but also to the underlying structure of the geographic ine the distribution of a set of architectural features data, which was also stored in PostgreSQL. PostGIS across the landscape would require a list of keys to provides its own robust GIS functions that work di- the data codes to interpret or query the database. rectly on the data. Using these functions rather than Web-Based Spatial Data Management 5

Web Browser

Internet / Intranet

MapServer

Shapefile

Fig. 6. Screen capture of geographic data maintained in Fig. 7. Diagram illustrating the design of the initial Mo- AutoCAD format (Courtesy Minnesota Archaeological rea GIS application (Courtesy Minnesota Archaeological Researches in the Western Peloponnese). Researches in the Western Peloponnese).

those embedded within MapServer or MapScript used in the original interface. Lintel configurations improved the application’s responsiveness and pro- are also translated to images that provide simple vided enhanced data analysis possibilities. guides for the user. In addition to revising the underlying data struc- One of the goals from the beginning of the project ture, we made several modifications to the site de- was to enable MARWP researchers or other individ- sign. The new site separated the geographic and uals to continue the inventory of vernacular build- database components into separate tabs with each ings remotely through a simple web browser. We tab activating a CSS container sized to take advan- believed that such a tool would benefit our project tage of the space available in the browser window. and provide a toolset that could be used in a variety A map tab provides tools and a large canvas for spa- of research applications beyond the Morea survey. tial queries, map display and digitization. A report Two applications provided capabilities that were tab offers a large canvas for the display of format- similar to what we desired but were not implement- ted data and multimedia elements. Since each tab holds data within a separate CSS container, it is possible to toggle between map and data views quickly without refreshing the data in either view. This new Web Browser design encouraged us to rethink our approach to data navigation and usability. The current application provides an indexed list of selected features in a pullout located on the right hand side of the screen. Internet / Intranet Users can select features from this list and view additional attributes that appear in the dedicated report tab (Fig. 9). The application translates the coded MapServer entries to easily understandable terms and formats the output in a structured report. Data describing villages and individual structures may be selected PostGIS together and displayed. The report tab presents additional multimedia elements to the user including inked drawings of the building elevations. To RDBMS improve legibility, coded attributes were replaced with images that provide graphic translations of Fig. 8. Diagram illustrating the design of the second the coded data values. Images of flat, combination Morea GIS application (Courtesy Minnesota Archaeologi- or curved tiles replace the coded values that were cal Researches in the Western Peloponnese). 6 Layers of Perception – CAA 2007

Fig. 9. Dedicated report tab enabling users to toggle between map and report view without refreshing the web page (Courtesy Minnesota Archaeological Researches in the Western Peloponnese).

ed due to cost and development preferences. ESRI’s with the first and last points appended to close the ArcGIS Server provides limited editing capabilities polygon. The user is then prompted to complete the through a web browser and there are some efforts data collection process by filling out a standard web to apply this application to SHPO needs. Unfortu- form with drop down menus and text boxes that nately, the cost of this application prohibited its use guide the user in the completion of the form. A date by MARWP. GeoServer (http://geoserver.org/) is an stamp is added to each record to capture the date OpenSource WMS and WFS-T server that provides that the feature was uploaded to the system. The co- attribute and geometry update capabilities, but we ordinates, attributes and date stamp are concatenat- were well into the development of the MARWP GIS ed and placed within an SQL statement that is sent when we became aware of this application and chose to the server. A PHP script on the server submits the to continue our efforts rather than begin develop- SQL commands to the project database which cre- ment on a new platform. Our redlining or remote ates a record in a review table. The uploaded data inventory tool used Walter Zorn’s JavaScript Vec- is immediately available to anyone accessing the tor Graphics Library (http://www.walterzorn.com/ MARWP website. But, the uploaded data must be jsgraphics/jsgraphics_e.htm). Zorn’s library pro- reviewed and approved before it is accepted and ap- vides functions for drawing a variety of geometric pended to the primary project database tables. This shapes and proved to be very efficient. The redlin- process limits the possibility of corrupting project ing tools are password protected but once accessed tables through accidental or intentional errors. users have the option of digitizing a point, line, or The development of the Morea GIS expanded our polygon feature. In the case of polygons, the points ability to present the results of the survey as well digitized on the screen are concatenated into a list as provide access to a variety of images of the Pelo- Web-Based Spatial Data Management 7

ponnese that were collected during the course of References the Pylos, Messene and morea investigations. The images include Landsat mosaics of the Pelopon- Brenningmeyer / Cooper / Verfenstein 1998 nese, pan sharpened Quickbird mosaics of ancient T. Brenningmeyer / F. Cooper / C. D. Verfenstein, Satel Messene and the Palace of Nestor as well as aerial lites, Silicon, and Stone: Spatial Information and Greek photographs flown during the final weeks of exca- Archaeology. Geo-Info Systems Magazine, 1998, 20–28. vation at the Palace of Nestor. We tested a variety Cooper 2002 of techniques for delivering large datasets through F. A. Cooper, Houses of the Morea (Athens 2002). the Morea GIS without significantly impacting the Cooper forthcoming speed of the application. Our Mapserver applica- F. A. Cooper, The Minnesota Pylos Project: Investiga- tion ran most effectively when serving GeoTiff -mo tions and Results, 1990–98. In: F. A. Cooper / D. Forten- saics. GeoTiffs are constrained to a4 Gb file size berry (eds.), The Minnesota Pylos Project 1, 1990–1998 which was large enough for our data. Images were (BAR forthcoming). pre-processed using the “gdaladdo” utility in the Geospatial Data Abstraction Library (GDAL http:// www.gdal.org/). This utility built multiple internal Todd Brenningmeyer overviews into each image, increasing the efficiency of the application at a variety of scales. This enabled Maryville University us to serve very large datasets, including a 1.5 Gb Department of Art and Design Landsat 7 Mosaic of the Peloponnese, with very lit- 650 Maryville University Drive tle change in the responsiveness of the application. St. Louis The Morea GIS allowed us to quickly make the full MO 63141 range of data collected during the course of our in- USA vestigations available to the general public. [email protected] The next phase of development involves building on the application described in this presentation. Frederick A. Cooper We are currently developing additional options for querying the database and integrating the spatial University of Minnesota query functions of PostGIS within the application. Department of Art History Our next goal is to integrate the Morea GIS appli- 338 Heller Hall / 271 19th Ave South cation with object catalogue and reconstruction Minneapolis software used to query and reconstruct fresco frag- MN 55455 – 0121 ments in the Palace of Nestor investigations. This USA will provide an embedded module for manipulating and examining artifacts on-screen which are tied to their spatial location within the GIS application. The Morea project shares the same needs as many environmental, architectural and archaeological surveys and the design and functionality used in this project can be extended to other areas of research. The hope is that this project will serve as a template for future development of catalogues of archaeological and historical materials.