2.3 EXAMPLES OF DATA ExpLORATION SOFTWARE In this section, we discuss numerous examples of data exploration software. First, we provide a historical per spective by considering some early attempts at data exploration: Moellering's 3-D mapping software, Explore Map, and Aspens. Second, we consider more recent software that was developed primarily with geo- graphers in mind as potential users: Map Time, Project Argus, Common GIS, and GeoDa. Third, we consider recent software that was not necessarily developed for geographers, but that certainly could be useful to them: HealthVis PCP, ESTAT, and IDV. 22.31 Moellering's 3-D Mapping Software early attempt to demonstrate the potential of data exploration. With Moellering's software, a user could explore a 3-D digital elevation model (DEM) in real time, a process that Moellering termed "surface explo ration." Because Moellering's software depended on Technically, the data were 21/2 D but exploration was done in 3-D space.