Ok, so this may be a more advanced topic than normally found on this forum. But I am struggling to classify the point clouds generated with the UAV. After Pix4D, after Agisoft or others you are left with an unclassified point cloud If I want to classify the buildings, vegetation, and ground points so I can then generate a DTM. How is everyone doing this? What software have you used, what settings?
The main problem I have found is that most point cloud manipulation software is designed for LiDAR, and LiDAR has one thing we do not have, multiple returns. So for them clasifying the ground is a matter of getting the last return and then just cleaning up the buildings. But most of these don't work so well with the point clouds from Pix4D, Agisoft, etc... I have tried LASTools, ESRI, and recently DTMaster. Any other suggestions? or suggestions on the settings to use?
The top if a Pt cloud generated in Autodesk Recap 360, the lower image is what Civil 3D 2015 can do with a tool they have to extract a surface from a pt cloud. They have three different modes you can use, two of them will attempt to remove the peaks. ie trees, cars building etc. One does nothing and just gives you the raw surface. As you can see from the surface most of the peaks are pretty much gone. Now it doesn't do much for grass, but doubt any software can.
Bill Neuhauser P.E.
AWESOME! Thanks for sharing that.
Amazing! It will solve a lot of problems!
Here is a test site I did. 56 - 14 GB photos from Nex-5 alpha processed in Photoscan to generate the point cloud and ortho. The red arrow is pointing to a Bulldozer to give a sense of scale. This is roughly 35 - 45 acres. Ground points classified in TerraScan and Contours generated in TerraModel. I'm pretty impressed with Photoscan's abilities.
Filter ground points in Photoscan then export point cloud (ground only) to LAS format.
Then from Whitebox GAT tools run the next sequence Bare-Earth DEM (usually with 0.5m resolution) > Remove Off-Terrain Objects > Fill Missing Data Holes.
I'm getting good results using this method.
Of course you have to change parameters according with terrain type and DSM resolution to get the best of it.
I'm using Recap360 as well with a GoPro for now to learn how to do this and learn how to fly the drone w/out too much damage to a DSLR. Last week we put the XYZ coordinates in the upload & downloaded it to an RCS. I don't have that file on this computer, I gave it to one of the engineers at my husband's soils engineering company.
Here's at least the rendering of a little less than 200 photos. I'm hoping to upgrade equipment in the next few weeks since the flying is going well & I'm getting very close with the photogrammetry. These are of a landslide repair
Amazing 360 degree view.
Have you tried Global Mapper's Lidar module yet? I've got it... Tried it, but with limited results. Just about every engineer I've talk to says get it done in India.
I tried it but I did not have very good results so I did not purchase it, the price seems steep and I did not give me very good results. I found a couple of articles that seem promising, I will have to try them out:
I think the key point from this is "not too much vegitation" lol! I live in British Columbia... Lidar, d'oh!