Three dimensional (3D) GIS analysis is an exciting and emerging relatively new use of GIS technology in CRM. DIGS predicts that 3D analysis will increase in use among archaeologists as the technology improves. 3D analysis is useful in CRM when resources are known to have subsurface components. Archaeological sites can be documented, mapped and viewed in 3D, which is particularly useful in post-excavation analysis and reporting. 3D analysis also has the potential to evaluate impacts to archaeological deposits, given the existence of the right datasets.
One recent innovative 3D analysis was completed for an area which was extensively modified through massive earthworks operations in the 1950s. A comparison of modern elevation data and derived historic elevation data resulted in a GIS model of the historic ground surface beneath the fill material (see the graphic below). This model identified the depth below modern ground surface at which the "native" river shoreline surface could be expected. In other words, through the analysis, the specific depth of the "native" ground surface below the existing ground surface was determined. The analysis was intended to provide project personnel with an understanding of which locations within their project area would encounter "native" soil the at the shallowest depsth (or, the "soonest"), assuming a uniform fill removal rate site-wide.
The analysis was particularly important in this culturally-sensitive area, where removal of the fill material had the potential to expose and disturb archaeological materials at the contact zone with the "native" ground surface. IMPORTANT: Note that while such analyses are not predictive of cultural resource presence, they do allow better project planning and strategizing to minimize potential impacts to cultural resources if they happen to be present. When cultural resource sensitivity is high, but actual conditions are not known or not verifiable, this type of analysis is the best alternative available.