In the BIM process, one is best served to start with a site survey, topo, & sub-surface soil investigation. The Survey & Topo is transferred by an electronic file to the Architect. This output file from the surveyor is produced in 3d and is ready to use as the base for the Architect's 3d model. The Structural 3d model is situated by the Architect in the Survey/Topo. From that moment on, all information can be directly related back to the surveyor's Benchmark or Elevation. The image to the left shows a top view of the model on the site with sections cut through the site and foundation. The green tint shows where the limestone (bearing) strata is located.
To Load Full Scale Drawing - See PDF - When Adobe loads, zoom to 200% then navigate around drawing to look at the detail.