Joined about 2 months ago
Forestry and utility corridors
on Archaeological site documentation with drone photogrammetry
This is the kind of project that reminds me why I got into this field. Stunning application of the technology. Did you use any ground control? Curious how you handled the accuracy without being able to place GCPs on the sensitive surfaces.
on Drone mapping in challenging terrain - cliffs, canopy, and elevation change
This is exactly where lidar earns its keep. Photogrammetry under canopy is basically useless for ground surface. If you have access to an L2 or similar, one lidar pass through those ravines would fill in all those canopy holes. Not saying you should have done it differently with what you had - just something to consider if this type of site comes up again.
on Point cloud classification - manual vs AI-based tools
TerraSolid's machine learning classifier has gotten really good. Train it on a manually classified tile and it does 80-90% of the work on similar terrain. Still need manual cleanup but it cuts processing time by 60-70%. The key is training on representative data. Forest terrain trains differently than urban.
on Drone LiDAR under $10k - is the DJI L2 finally good enough?
Running the L2 for 4 months now. Point density is excellent - getting 200+ pts/m² at 50m AGL. Bare earth extraction under moderate forest canopy is surprisingly good, 3-5 returns per pulse. Accuracy on checkpoints: 2-3cm horizontal, 3-5cm vertical with RTK. Comparable to what we were getting with the Zenmuse L1.
on QGIS for drone deliverables - anyone doing this professionally?
I use QGIS for 80% of my GIS work and ArcGIS for the other 20% (mainly 3D visualization and some specific analysis tools). Totally viable for standard drone deliverables.
on How to achieve sub-centimeter accuracy with drone surveys
If they truly need sub-cm, they need LiDAR or terrestrial methods. Photogrammetry has physical limits. A well-executed drone survey with RTK and GCPs will give you 1-3cm. That's the sweet spot. Anything claiming sub-cm from photogrammetry over a large area is either cherry-picking data or flying at absurdly low altitudes.
on Before/after of vegetation encroachment on power line ROW
This is exactly the value prop for utility LiDAR. Photogrammetry can't see through trees to identify the actual conflicts. Did you deliver a clearing priority map?
on Landslide monitoring project - 6 months of drone data
This is incredible data. The M2C (multiscale model to model cloud comparison) in CloudCompare is perfect for this. Are you using it or doing simple cloud-to-cloud distance? We did something similar for a coastal erosion project and the temporal data is so much more valuable than single-point surveys.
on Cold weather drone operations - tips for Alaska/Canada folks?
For LiDAR specifically, let the sensor warm up before collecting data. Cold affects the calibration. We run 5 minutes of hovering before starting survey lines.
on Battery management in cold weather - what's your approach?
Heated battery case is the move. I use the DJI battery station in my truck with the heater running, rotate batteries so they stay warm. Never start a flight with a battery under 68°F. Also fly slower in cold - the motors work harder in dense cold air.
on Is the Zenmuse L2 worth it over L1?
@UtilityUma That's exactly what I needed to hear. The under-canopy performance is our pain point. We're always fighting with ground classification in the vegetated sections. If L2 actually improves that, it's probably worth the upgrade cost for us.
on Fixed wing for DOT corridor work - Wingtra vs Trinity?
Different question - are you considering LiDAR for corridors? If there's any vegetation encroachment into the ROW, photogrammetry won't see it. We do a lot of utility work and ended up adding an M350+L2 for the vegetated sections. Wingtra is great for open corridors though.