LiDAR vs. photogrammetry: when to fly which

Ask which sensor is better and you will get a debate. Ask where each one fails and you get a decision. LiDAR pulses reach the ground through canopy gaps, which makes it the only serious option for bare-earth terrain under vegetation. Photogrammetry sees only what the camera sees — the top of the canopy, not the ground beneath it.

Photogrammetry earns its keep on open sites. Over bare ground, stockpiles, pavement, and structures, a well-flown photogrammetric survey delivers dense, colorized surface models at a fraction of LiDAR's sensor cost, and the orthophoto that comes with it is a deliverable in its own right. If the client needs to see the site, not just measure it, the camera is doing double duty.

Budget is the tiebreaker less often than people expect. The real costs are re-flights and rejected deliverables: photogrammetry flown over moving water, uniform snow, or dense vegetation produces holes and noise that no amount of processing rescues. Price the failure modes, not the flight.

Our rule of thumb after hundreds of missions: vegetation or engineering-grade ground surfaces mean LiDAR; open sites where imagery matters mean photogrammetry; corridors and complex jobs usually justify flying both, because the sensors cover each other's blind spots.