Metrology is the study and application of measurement. Distances between property corners, elevations on site topography surveys, footings of structural steel, and centerlines of pipes are objects that increase in value when measured.
Accuracy, Precision, and Error
Our technicians measure on site with a variety of techniques and best practices to increase accuracy as cost efficient as possible. The measured accuracy is a factor relative to the actual position. Precision is a level of confidence in the measurement, best represented by the number of significant digits. If I walked through a door and hit my shoulder on the frame, I wasn’t very accurate; but if I hit my shoulder ten times a day, at least I was precise! In all measurements, there are sources of error that decrease accuracy and precision. Survey technicians are aware of these errors and seek to eliminate them by good field practices.
Survey equipment includes steel pocket tapes and fiberglass reel tapes with distances collected in field books. One of the most accurate piece of equipment in our truck is an autolevel used to project elevation data optically. We also use electronic distance measurers that emit light waves, reflect from survey prisms, and return a distance and angle for an electronic data collector to record. The advancement of the total station now includes robotic tracking and prismless distance measurement. Measurements can also be collected by inverse from GNSS positioning equipment.
As site topo surveys increase in complexity to include mechanical and structural elements, conventional survey methods and GNSS data collection begins to weaken. Southern Survey uses high definition light detection and ranging (LiDAR) to collect millions of points and measure a 3D world of XYZ point clouds.