How Long is the SLAC Gallery

摘要

The SLAC Communications Department contacted Metrology to inquire about the length of SLAC's Gallery, building 002. Initially, Metrology's Alignment Engineering Group (AEG) proposed to import SLAC's orthophotos into a CAD platform (Microstation). A draftsman could then graphically pick two points at the Gallery's extreme and measure the distance between them (3074.8m). This would be a fast method of producing the length of the gallery, but could be in error by several meters due to photo rectification. The Communications Department required a more accurate measurement.