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Mapping trees is a tricky thing - photogrammetry vs LiDAR | DroneSurvey

c/techniques•Posted byu/LarryTheMapper•16 days ago

Mapping trees is a tricky thing - photogrammetry vs LiDAR

Working on a forestry project that needs canopy height modeling and below-canopy terrain. Obviously photogrammetry can't see through trees so the DTM under tree cover is basically interpolated.

LiDAR gets through the canopy but the drone LiDAR units are expensive. Has anyone used a combination approach? Photogrammetry for open areas and supplemental LiDAR for forested sections?

Or is it better to just go full LiDAR for these kinds of projects?

Comments

cascadedroneguy•16 days ago

We do a lot of forestry work in the PNW. Full LiDAR is the way to go if the budget allows. The DJI L2 on the M350 is around $15k and it handles tree canopy well. Getting 3-5 returns per pulse.

The combination approach works but the stitching between photo-derived and LiDAR-derived surfaces is messy. You end up spending more time on data fusion than you save on equipment.

uma_geomatics•16 days ago

For canopy height specifically, photogrammetry actually works well. You just need a bare-earth reference DEM (USGS 3DEP or similar) and subtract it from your photogrammetric DSM.

Won't give you stem counts or understory detail but for general canopy height modeling it's surprisingly effective.