Ditched drones for lidar scanning on a big site and it paid off big time

Had a 12 acre lot in Austin that we needed to map for drainage planning. The crew was split on using a DJI drone for photogrammetry versus going with a Leica BLK lidar unit. I pushed for lidar because we had heavy tree cover and I didn't want to mess with stitching hundreds of images. Drones are cool but that canopy would have wrecked the accuracy. Spent about $400 extra on the rental but we got the whole site mapped in 4 hours instead of 2 days. The point cloud cut through the trees clean and the grading plan came out perfect. My main question is has anyone else run into photogrammetry failing hard in wooded areas or is it just me?

4 comments

4 Comments

xena58225d ago

Man honestly I used to swear by photogrammetry for everything, but your story just clicked something for me. I had a similar sized job near Seattle last year with heavy doug fir coverage and the drone output was a nightmare to clean up. The tree shadows created weird gaps and the final mesh had these random holes that took forever to patch. After reading this I'm definitely gonna push for lidar next time the tree cover gets thick. The speed difference alone sounds worth the extra cost.

harperp2425d ago

Bring up something nobody's talking about though - how much of a pain it is to store and process all that lidar data. I got a quote for a project last month and the raw point cloud file was like 40 gigs before I even started cleaning it up. My old laptop couldn't even open it without crashing. If you go lidar make sure your computer can actually handle it.

spencer_gonzalez125d ago

Dude tell me about it. I bought what I thought was a beast of a laptop specifically for lidar work and the first time I tried to open a full scan I watched that thing freeze for a solid five minutes. Felt like I was back in 2005 trying to run Sims 2 on a family computer. The processing power argument is real and nobody warns you about it upfront. You basically need a dedicated hard drive just for the raw files and a separate one for backups or you're asking for trouble.

olivermason25d ago

Respectfully, I see it a bit differently. That Seattle job you mentioned actually sounds like a place where photogrammetry could've worked fine with the right flight planning and overlapping images, and lidar's cleanup and processing time can be just as brutal (ask anyone who's spent a weekend filtering out ground points).