Mapping the side of a mountain with trees

Have an experiment use case tomorrow but it involves mapping a parcel that is basically all trees and the property like on the south side is a mountain peak (small mountain but still). Any ideas on how to deal with the elevation and especially how to get all the trees to stitch? Right now I have my map at 398 and 75/75 and it’s still an hour of flight time.

I map my 17 acres with 80%/80% overlaps at 300’ and my trees stitch pretty reasonably as shown below.

I get much better results flying missions on overcast days with low wind. Anything else gives poorer results. I subtract the LiDAR bare Earth elevation from that of the DroneDeploy 3D model and make conformal 3D elevation maps. These have enabled me to discover the tallest trees in the 17 acres. The lot drops off 160’ to the East (right of 2D map above) and so we never realized we had such tall trees, over 140’ high.

I load the 3D .obj model in Rhino and then color the 500,000+ vertices of the mesh according to Zmodel - ZLiDAR bare Earth. Purple-going-to-Black is the LiDAR bare-Earth reference, and black-going-to-white marks the tallest trees. This view is from a little South of East looking towards a little North of West. It uses 70 colors with approximately equal perceptual differences. I can also do the map with some texturing showing (but not as heavy handed as in DroneDeploy):


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Depending on the elevation change you might want to use multiple flight plans staggered up the mountain side. You should try and keep the drone no closer than 250 feet to the highest trees. So your 400 foot altitude is good until the elevation rises 150 feet (also consider 400 feet is above ground level - the tops of the trees may be 100 feet higher than that so your effective altitude is 300 feet above the tree canopy). You should then set another flight plan at 400 feet (150 feet above your first one) starting there and cover the next 150 feet in elevation. I’d prefer to say every 100 feet in elevation, but you can try 150.

I just finished mapping 3400 acres of steep Forrest land. The steepest parcel had 1600 vertical ft to 5000 horizontal. I used the Map Pilot App that has an awesome terrain following feature. After you plan your mission, it creates a profile and 3D waypoints from SRTM elevation data. I used 85% side and end lap.

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Terry: I’m a newbie to this, and trying to get my stuff together. Your application appears to be exactly what I’m trying to accomplish, on about 170 acres. I think I have sufficient lidar ground level data from regional scans, and so need to employ drone deploy (with a DJI Mavik Pro) to start the 3D data capture process from which to subtract ground data. Can you give me some additional start-up tips? I don’t even yet have sufficient computer hardware/software, so even tips on those requirements would be very helpful to my initial infrastructure decisions. Also, have you done any georeferencing or ground control points on your property boundaries? Any tips on that?
Thanks for anything you are able to share!!

@Tunnel8, Is this for fun or business? If for business I would look into Carlson Precision 3D. It is a purpose-built comprehensive point cloud editor. It was designed to work with almost any design and engineering CAD softwares and support LIDAR. You can combine data and do takeoffs between the different data sets. Available as a one-time purchase or maintenance subscription.