The error from three different surveying techniques- level, hand-held barometer, and hand-held GPS-were compared in terms of accuracy and cost effectiveness for hydrogeological studies by surveying a four-kilometer Tattoo circuit within the campus of the Universidad Nacional Autonoma de Mexico.The polygon was surveyed once with the level and the barometer, and twice with GPS.Vertical errors were 17 mm, 13 meters and Wireless Over-Ear 114 meters, for the level, barometer and GPS, respectively.Of the three options, the first is by far the most expensive.
Thus, the preferred method for height determinations continues to be the level, even if it is the more expensive option.