How to improve OrthoPhoto and 3D image quality for elevated structures, tubing, and columns

I have processed a few maps, trying to obtain the best image quality for OrthoPhotos and 3D models to determine feasibility using in a project. I am using a DJI Mavic 2 pro, with droneDeploy to create the flight mission, and then processing the collected data using WebODM on a linux laptop with i7 and 16G ram. The most important part of the surveys for my project is the accuracy of the structures, tubing and columns, as I plan to add tags / labels to specific locations on each of these items in the generated models. Below is a link to an example from one of my test projects.

Any suggestions on how to improve the output results?

Should I break up the projects into smaller more focused / zoomed areas (Submodels), each with multiple Point of Interest flight plans at various radius and elevations?
What type of flight plan might work best, and is there a manual flight mode for DJI that takes photos at set distances from the previous point?
Should a camera calibration flight plan be incorporated in each projects flight plans when a 3D model is the desired result and how should it be different from the mapping flight plans at 20degree angles and camera looking forward 5 degrees?
What distance should photos be taken if I want to show the routing of 2 or 3" width tubing or bars accurately? I am seeing rough or jagged stitching of some of the smaller tubing and columns that I hope to improve upon.

In my pro-surveyor opinion, everything comes down to required precision/scale and LOD. Then the required GSD (Ground Sampling Distance) depends on the parameters of the camera (mainly camera resolution and focal length) and the flight altitude. As a rule of thumb, you will be able to get measurements of absolute location at an accuracy of one to three times your GSD.

As a ballpark estimate example, to achieve ground accuracy of 3 cm you would need a 1 cm (3 inches) GSD or pixel size using a drone like the DJI Mavic Pro you will need to fly at an altitude of 25 m. For most professional surveyors, it is recommend a GSD of 1 cm or less in combination with PPK data or at least 4 GCPs. To get best 3D results add the following flight angles to your 3D optimized grid-shaped flight plan and you’ll be fine for most AEC jobs: Set1 Nadir (0 degree), Set2 Oblique (45 degrees), Set3 Oblique (80 degrees) and Set4 Overview (30 degrees).

Drone Angles

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Incredibly valuable post, IMO. Thank you.

Source :

Feedback from one user (need to look for complete study or thesis) and could differ when processing from different software. What is sure is photogrammetry loves angles and different altitudes. Lot of pictures could lack in speed up processing, mixing between data collection and angle/elevation is the key but it should mention over/sidelap

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Thanks for the valuable input! Definitely several adjustments to accommodate in my next project.

I’m mainly using ODM to create orthophotos from agricultural fields. From times to times I try to create 3d models of buildings, so far only with one gimbal setting: 0 ° as I use it for the orthophotos.
While researching how I can improve my results, I came across your post. Thank you for that!

My question at this point: Can all images of the 4 sets with the different angle settings and flight heights be loaded into ODM and processed at once? Or does it have to be done in different work steps?

Many Thanks

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Welcome! Great to see another Agricultural Field Survey person (though I had to leave the industry) :slight_smile:

Usually this will work just fine! Obvious caveat about RAM if you really have a ton of images, though.

Hi, thank you for your fast answer!

Before I start my first real 3D test-project, I have one more question for you:

Which, preferably free capture app, would you use to take the photos?

To take the 0 ° recordings I use DJI-Flight-Planner and Litchi and I think there is no easy solution with the Flight-Planner to create different sets with different camera angles …

I’m working with the DJI Mavic 2 Pro

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Any time! Welcome to the community.

Hmm, I’d give Pix4D Capture a go. Unfortunately, I have no experience with it using your sUAS, but it did work nicely for me back in the day on my Solo (though I much prefer Solex).

How quickly are you flying? You have a rolling shutter on that drone. Have you tried a stop/go flight plan? Just a thought.

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