Comparing Orthophotos

I update progress on a nearby construction site, including mapping, and have been producing orthophotos using Drone Deploy. I initially compared those results to WebODM orthophoto with all-default settings and was disappointed that DD was clearly a better image. Then went back into WebODM and re-ran the same file with the Hi-Res template and found that it was maybe a little better than the DD product. Nice!

After reading the Blog recommending the Brown-Conrady lens option as an improvement over the default lens, I again reran the data set with the Hi-Res template edited to the Brown lens. I found the Brown lens to be better in some ways than the default and not quite as good in others. Can’t characterize a compare/contrast, but they were just slightly different to one another and both seemed slightly better than the DD product in many ways, although DD had a very nice orthophoto.

If anyone is interested, I’ve uploaded all four orthophotos to dropbox at this link: https://www.dropbox.com/sh/9o7gijgysx76qot/AAD1QT7XtgPHopFyczwmlcqIa?dl=0

I’ll also upload the data set to the ODM data pool if anyone wants to work on it themselves. This construction site offers a rich set of features for comparison. Lots of different textures, some vegetation, some reflections on water, lots of different colored items that should be straight lines, some highway, cars, structures, etc. This project is known as Miracle Park and I’ll label the file that way. It’s 122 JPGs, and ran in WebODM on my dual-quad core 60GB PC with these times (H:MM):
All defaults : 1:40
Hi-Res template: 3:43
Hi-Res with Brown lens: 3:35

The orthophotos had these GeoTIFF file sizes:
DroneDeploy: 678MB
WebODM All-Default: 154MB
WebODM Hi-Res Template: 867MB
WebODM Hi-Res with Brown: 867MB

Offered in case anyone else is searching for answers to orthophoto resolution questions. Images recorded with Phantom 4 Pro. Best regards… Bob R.

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A couple of suggestions for starting a comparison:

  • check the differences in the reflections on the standing water in the detention pond
  • check the ladder on the side on the truck in the different images
  • check out the linearity of the blue plastic pipes laying on the ground and the metal roof on the fire house in the upper left corner.
  • the track hoe is kind of interesting also. The tracks and arm didn’t resolve well in any of them.

Sorry I don’t have the chops to put these into the Arena-style slider. You’ll just have to open the images and click back and forth.

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Great info. Thanks, Bob!

Bob,

I played with the dataset and WebODM parameters to produce a 3D Model and Orthophoto.
Here are the parameters used: mve-confidence: 0.4, texturing-nadir-weight: 32, orthophoto-resolution: 1, dem-resolution: 4, mesh-size: 300000, mesh-octree-depth: 11, dsm: true, camera-lens: brown, depthmap-resolution: 1000, texturing-data-term: area.
This is my first time using the Brown lens option.

I have been testing odm parameters to have high resolution models and orthophotos just like those resulting with other software. I must admit that creating a nice orthophoto in urban environment using WebODM is somehow challenging.
I expect some critique on these parameters.

Processing time for these settings was 01:05:05 using a WebODM Lightning Processing Node.

The resulting 3D model is good, at least for observing the excavation works.

I compared results from DD and WebODM, on these links you will find the comparison, orthophoto and the textured model.

Comparison:
https://1drv.ms/b/s!AvHdULm25qZYlaVyVCOWV_9HdNMh8g?e=iFRile

Orthophoto:
https://1drv.ms/u/s!AvHdULm25qZYlaVcIb-5CL6GnwoDuA?e=3h9tAT

Textured model:
https://1drv.ms/u/s!AvHdULm25qZYlaV2ZnXQGJmLYUAnIQ?e=lKru7D

Thank you for sharing

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Hello Israelbar – found your post just as I was winding down for the evening. Will enjoy looking through your work this weekend. Hope you found the data set useful. Have you drawn any conclusions from your study?

Bob R.

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