Measuring Elevation for Dummies

surveyors without a GPS

When it comes to lousy answers to simple questions, we here at the Antisocial Network always turn to our friends at the mother lode of misinformation, eHow.com. You can almost always find an answer that's wrong for one reason or another by visiting a Demand Media niche site, and today's no exception. Returning DotD Nicole Schmoll is here to both under- and over-explain an interesting topic, "How Is Land Elevation Measured?" for CareerTrend.com.

Our immediate problem is that the question is ambiguous: did the OQ want to know what techniques and instruments are used for measuring elevation? Or did the OQ simply want to know what reference point is typically used, the answer to which is, "Mean sea level (MSL)." If the latter, Schmoll's answer will be of no help at all, since she immediately zeroed in on one technique: surveying. If the former, the answer is of little help because, frankly, Nicole wouldn't know a surveyor if one fell on her head...

According to Schmoll, a self-appointed freelancer whose background was, as is so often the case at eHow, "communications," you measure land elevation thus:

"Select the spot which you want to measure the land elevation for. Go to that spot. Place stakes in the ground along the borders and in the center of the area you want to measure. Set stakes or markers up every 10 feet."

Already we're getting a little confused: apparently Nicole wanted to survey an area. We think setting up a 10-foot grid might be a little awkward if you're surveying a plot that's one mile square (more than 20,000 stakes...). But moving on: Schmoll said to use a GPS to collect the data, including such scintillating instructions as

"Understand that your GPS will determine land elevation by computing the distance between each marker and the satellites orbiting the earth. Based on a pre-programmed mathematical calculation which considers the exact orbital path of the satellite, the pseudo random noise (PRN) of your GPS device and the position of your marker, your device will calculate the exact land elevation for each marker point." Wow, that's telling them, Nicole! And the copy editor let you use that explanation... good old eHow! And it's a good thing she could embed that black-box stuff, because otherwise she wouldn't have met the minimum word count...

Moving on, Nicole instructed the reader to

"Take your GPS device and data collector back to your home or office computer or download the data to a laptop field computer..."

...which we think raises the question, "If you have a 'laptop field computer,' why would you need to take the data back to the office?" But never mind: Schmoll would have no idea, anyway.

Schmoll's explanation depended on modern technology and glossed over how that technology works (sciences are hard!) while ignoring the basics of surveying. Schmoll neglected to inform her readers of the accuracy limitations of GPS technology and completely ignored methods that include mathematics (also "hard") and surveying instruments such as a transit and plane table. In other words, she knew nothing and, after reading her answer, the OQ knew little or nothing as well. Congratulations, Nicole, on your second Dumbass of the Day award!

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