Laser Surveying Technology

  • Posted on Aug 6, 2019

For as long as people and nations have claimed ownership of land, accurately measuring and defining a piece of dirt is important. 

The Egyptians measured land for the purpose of taxation and building the pyramids.  The Greeks advanced the science of geometry and invented first piece of surveying equipment.  Both the Romans and the Greeks used the human foot to make (highly inaccurate) measurements. 

A 16th-century mathematician, Leonard Digges, invented the theodolite.  A theodolite is basically a telescope mounted on a swivel placed on a tripod and measures both horizontal and vertical angles.  Theodolites offer very accurate results measured in seconds of the 360-degree circle (degrees/minutes/seconds).  A 2-second theodolite is extremely accurate for objects up to 2,000 feet away.  Most errors at this distance are human in nature due to improper leveling or hasty readings.  A prism is used to reflect infrared light back to the instrument, so early theodolites required 2 surveyors.  

Modern electronic theodolites only require one surveyor since the person holding the prism can operate the laser remotely.  This makes street and highway surveying safer and doesn’t block traffic.  Laser surveying is much more accurate and is especially useful in uneven terrains.  They do not work for under water or water surface measuring so ultrasonic tools are used instead.

Whereas modern electronic measuring tools use one laser beam  to accurately measure the distance between 2 points, 3-D laser scanners use 50,000 beams to map a 3-D model.  These tools are especially useful for small spaces and tunnels and for outdoor construction project planning.  LiDAR (Light Detection and Ranging) produces very detailed images in short periods of time.  LiDAR technology is expensive and the data takes up a lot of space so it’s not yet widely used in land surveying. 

Global positioning systems make land surveying exponentially quicker and more accurate.  What once took teams of surveyors weeks can now be done in one day.  GPS surveying is not limited by line-of-sight problems since all that is required is an area open to the sky.  GPS systems are lightweight and easily transported.  Data collection is quick and can be communicated wirelessly.

Will drones replace human surveyors?  It’s too soon to know but certainly they can get to remote places very easily. 

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