How Modern Technology Improves Topographic Maps

Topographic surveys, sometimes called "topo surveys" for short, show not just the contours but the
terrain, elevation, and natural and man-made features of a parcel of land. They have been used for
centuries by engineers, architects and other designers to decide what kind of construction is best fitted to the land, and what changes may need to be made to build on it. While historically surveyors used various optical leveling instruments to make a topographic map, the modern Los Angeles topographic survey employs more high-tech solutions.

An aerial topo survey is one of the most useful innovations. These surveys are performed by taking
photographs in an airplane or helicopter at a specific distance from the ground. Multiple photographs
are taken from different points over the land. Then the elevation is calculated by comparing pairs of
photographs to create a kind of 3-D perspective, the same way our depth perception works by seeing
the world through two eyes.

However, aerial surveys are limited in how accurate they can get, so sometimes a Los Angeles
topographic survey must be performed on the ground. The surveyor walks over the entire land, taking measurements at specific intervals depending on how precise the survey needs to be. Modern surveyors use survey-grade GPS equipment. While the commercial GPS in your car or cellphone may be accurate down to a few feet, a survey-grade GPS, when carefully calibrated, can be accurate down to a few centimeters, or even millimeters if it's kept stationary for a period of time. Survey-grade GPS units also calculate vertical as well as horizontal location, measuring the exact height of a particular point.

Having a good topographic map is essential in starting any major construction project. Whatever purpose it's going to be used for, modern technology can ensure that a Los Angeles topographic survey is accurate down to as precise a degree as a designer needs.