3D Model with Dronelink
I'm having problems getting a nice 3D model with my DJI Mini 3 Pro.
What are the optimal values for an object (building roof and facade)?
It should look good and be used for surveying.
Flight altitude over object?
Different flight altitudes make sense? If yes, at what distance?
Gimbal tilt at any height?
Lateral distance or distance to the building?
For facade missions, what is the optimal distance to the object?
What is the best software for creating 3D buildings on MAC M2? WEBODM does not provide nice images in my opinion.
Which is the best software for measurements?
Thank you very much for the HELP!
Greetings from Zurich, Switzerland
Comments
4 comments
Well this was created using a mini2, dronelink facade mission https://app.dronelink.com/martin-reading/derbyshire/plan/D2QDjJ4kl3bQpkaomez7 and WebODM, and I'm fairly pleased with it, it could do with a bit more work, possibly a few nadir images, but that will have to wait till the spring now
https://youtu.be/Dwc_rdJj9nI
-Always start with a Nadir capture (90 degree gimbal angle) with at least 70 per cent vertical (forward) overlap and 60 per cent side overlap. Then fly a double grid Oblique capture (60 degree gimbal) with 80pc vertical and 70pc side overlaps. Flying multiple Oblique passes at different altitudes isn't usually necessary unless the structure is complex, like an ornate cathedral or bridge span. As a rule of thumb, I would start at 35m AGL,65 degree gimbal and bring the gimbal up 5 degrees for every ten metre reduction in altitude.
-Due to the small sensor, you should fly as low as is safe, having regard to obstacles like trees and the structure itself. You have not said how large or high the building is so I can't give advice on altitude but I just did a two storey house at 20 metres with a Mini 3 Pro and that came out well.
-You won't get a survey quality capture from a consumer drone like Mini 3 Pro but with study and practice you can make it look good and get good enough accuracy for practical use, particularly if there are survey marks captured in your scene and you learn how to use them as ground control points.
-For facade missions, the distance to the face will depend on the size of structure and obstacles in the vicinity. The closer you are, the more shots you have to take but a small sensor like on the Mini 3 Pro needs to be quite close to get the resolution needed for detailed textures and mesh. This will be a balance between quality and efficiency, depending on the size of the subject. The same overlaps are required for the facade as mentioned above. If the gimbal is perpendicular to the surface use, 70/60. If it is oblique to the surface use 80/70. When scanning facades pay attention to overhangs like roof eaves and deep window frames. You might need to use slight positive gimbal angle of 5-10 degrees up to scan under those.
-It sounds like Agisoft Metashape would be the best processing software for your needs. It has a 30 day free trial. Agisoft has a free viewer in their Downloads page that includes measurements.
Greetings from Tasmania, Australia.
Thank you for the great advice. I'll try this in the next few days.
Check out the opendronemap (which is what is under WebODM) documentation where they cover a lot of this including using offset grids, overlays for 3D, ect. You can find it here: https://docs.opendronemap.org/tutorials/
Also, web Agisoft Metashape. They have a free trial version that will let you try things out. In many cases that can give better results, but the is a lot more expensive.
Please sign in to leave a comment.