What is LiDAR Survey and When Should You Use It?

Most people have heard of drone survey. Fewer know about LiDAR, and even fewer understand when it is genuinely necessary versus when a standard photogrammetry survey would do the job just as well for a fraction of the cost. This article explains what LiDAR actually does, what it produces, and the specific project conditions where it becomes the only sensible choice.

How LiDAR Works

LiDAR stands for Light Detection and Ranging. The sensor emits thousands of laser pulses per second toward the ground. Each pulse travels down, hits a surface, and bounces back. The sensor records exactly how long that return journey took. Since light travels at a known speed, the system calculates the precise distance to each point that reflected a pulse.

The result is a dense 3D point cloud — millions of individual XYZ coordinate measurements of the terrain and any structures on it. This point cloud can then be classified: ground points, vegetation points, building points. Once classified, you can generate a bare-earth DTM that shows the true ground surface with all vegetation removed.

A drone-mounted LiDAR sensor. The rotating head emits hundreds of thousands of laser pulses per second.

When to Use LiDAR vs Photogrammetry

What Does a LiDAR Survey Deliver?

LiDAR data is compatible with ArcGIS, QGIS, AutoCAD, and most civil engineering design platforms. If your design team uses Civil 3D or 12d, a LiDAR-derived DTM feeds directly into corridor design without any extra processing step.

For transmission line projects specifically, LiDAR corridor surveys are increasingly specified by clients because the bare-earth terrain data produces more accurate sag calculations than any other survey method. If your project passes through forested terrain, LiDAR is not optional. It is the only way to get the ground surface.