digitizing

During Phase 1, teams alternated between recording conditions in the field and digitizing the survey information in AutoCAD®. A searchable database in Microsoft Access® was also created, cataloging the condition of each stone surveyed. Conditions were later imported into ArcView® GIS software to allow for greater diagnostic manipulation. With Phase 2 the decision was made to employ ArcView® as the primary vehicle for entering the data, as it offered more options for displaying and representing data in addition to its analytical capabilities. Every condition, as well as any distinct architectural features (e.g., joints), was digitized and placed in its own layer, allowing specific conditions (layers) to be turned on or off in order to view the drawings in various relational contexts.

After documentation was completed, attention focused on the columns of the north and south porticos, as they exhibited the most serious relative deterioration. With all of the conditions mapped in GIS, incipient spalling, major and minor cracking, and material loss were isolated to allow for clarity of analysis. Basic GIS capabilities then allowed first for the calculation of the area of each spall and then the area of spall as a percentage of total surface area for each of the 168 drums comprising the eight columns, and the percentage of total spalling found on each drum. This information then allowed the drums to be ranked in order of their severity, identifying the areas which were experiencing the most severe deterioration and helping to prioritize locations for treatments (see Milner & Carr, 2007). (18MB)