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Author Topic: Fixing/avoiding poor image quality?  (Read 823 times)

spitzer6

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Fixing/avoiding poor image quality?
« on: October 26, 2021, 06:07:30 PM »
Hi all! I am using a DJI Phantom 4 Pro and Agistot Metashape to create DEMs and orthomosaics of beaches. When I go to estimate image quality, a lot of the initial pictures in the flight will appear blurry and washed out and are very difficult to process. We use the auto settings on the camera. Any tips on fixing this in post production or fixing the problem in the field? My guess is to change the ISO settings in the camera but would like other opinions.

Bzuco

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Re: Fixing/avoiding poor image quality?
« Reply #1 on: October 26, 2021, 09:48:40 PM »
Hi, you need to figure out if the blurriness is from "motion" blur or "out of focus" blur. Can you post one best and one worst image?
In EXIF info of your photos you can see exposure settings, it will tell you why was the photo bad.

Some advice:
-set white balance to cloudy/sun/custom, do no use auto
-if autofocus does not work well, set manual focus and try to keep same height, or refocus manually if needed during flight when height from ground will changed.
-choice shooting mode to aperture priority and set: ISO 100,  lowest aperture number and check what is the resulting shutter speed. If it is 1/200s it should be enough for stable not fast flight...it depends also on flight altitude. If the resulting speed is way higher(1/500s...1/800s) you can try increase aperture number to 4 / 4,5 / 5.6 and check if shutter speed is at least 1/200s.

Magic behind lens aperture:
Low aperture values produces more sharper images in the middle, but can cause unwanted chromatic aberation effect on sides/edges, higher values produces less sharper images, but without chromatic aberation. Yout need to find some sweetspot for your lens where you will be satisfied in terms image quality, blurriness/sharpness. Maybe final aperture value will force you to increase ISO, because resulting shutter speed will be not enough for motion blur less images......playing with these 3 exposure parameters is important for photogrammetry.
Fixing this issues in post production does not make much sense.
« Last Edit: October 27, 2021, 04:04:33 AM by Bzuco »

Steve003

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Re: Fixing/avoiding poor image quality?
« Reply #2 on: October 26, 2021, 11:51:15 PM »
Hi,

its a bug !

having spent 2 weeks trying to resolve blurred textures, now seeing a number of posts with same issues, Agisoft havent said anything much.
I am having to use Photoscan to get textures made. I have sent projects to Agisoft almost 3 weeks ago, .

I am also finding that metashape wont align all images, sometimes even images that were aligned in a different chunk same project, very nice images.

Photoscan aligns all images, bit is HORRENDOUSLY SLOW AT DOING A PROJECT. I have never had total workflow success yet from meta. In photoscan it was just slow, in meta things failed. I am not convinced on meta being better yet, keep having to use Photoscan, but love meta's mesh from depth map and speed.

and I have just read in a different part of the forum , bug reports

https://www.agisoft.com/forum/index.php?topic=13701.0

Its a bug in 1.7.4

3 weeks wasted.

I wish we all were told,  rather than have us think we the user are not doing something right.

1.7.1 apparently is best until they fix it.,

How does one get hold of 1.7.1 ?

Steve

Bzuco

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Re: Fixing/avoiding poor image quality?
« Reply #3 on: October 27, 2021, 04:16:42 AM »
@Steve
He is talking about a completely different problem that is not related to the problem you are describing.