How to avoid these artifacts ?

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g0b
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Joined: 26.02.2009 00:39

How to avoid these artifacts ?

Post by g0b » 16.07.2009 19:25

Hi,

After many tries with stacking methods and parameters, this is the best I can get (from around 200 images). Has anybody ever experienced these artifacts (too many to get rid of with the retouching tools), and found a way to remove them ? :

A : Hairs are only partially visible and smeared. This occurs on vertical sections (on less steep ones, it's ok)

B : On place with overlapping features, the background is sometimes removed.

C : Hole on the edge of the arm (whereas there is no such artifact on any of the pictures of the stack)

D : There is a zone with no details at all, whereas it's not the case on the pictures on the stack

E : Colored halo (kind of blooming around small features of the image)

Regards,
g0b
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g0b
Posts: 26
Joined: 26.02.2009 00:39

Post by g0b » 19.11.2009 02:36

Bump !

Nobody for a hint on these ?

g0b

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Stas Yatsenko
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Post by Stas Yatsenko » 19.11.2009 13:04

I would suggest you to set Depth map smoothing on the Preferences/Autoadjustmento to 0. And I think the overlapping can be too big, I would use every second or every third image to see how it would change the result. You can also set interpolation to bilinear to speed up the processing.

I would like to experiment with this stack. If it is possible, please upload jpeg files resized to about 4Mpixels to our ftp site (http://heliconsoft.com/ftp.html)

g0b
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Post by g0b » 20.11.2009 01:36

Hi,

Thanks a lot for your help.
I've tried to lower depth map smoothing and to take one picture out of 3. But it didn't change much the result unfortunatly.

Upload of the stack on your ftp is done (196 pictures in /Ant_Issue)

Do not hesitate to ask me more information.

I would be very happy to hear from you about this issue, because I'm a bit struck with all the images I want to process.

Regards,
g0b

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Stas Yatsenko
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Post by Stas Yatsenko » 24.11.2009 14:33

g0b,

I've played with your stack yesterday. I am amazed that even 200 images with F8 do not have excessive overlapping! A remarkable stack that produces very smooth 3D model too. I found that method A, Radius 16-24 and Smoothing 1 give the best result to my taste. It is not perfect but smooth,natural looking and preserving fine details in difficult places.

Guest

Post by Guest » 25.11.2009 14:09

Hi Stas,

Thanks A LOT for your help.
I realized that I tried a range of parameters far too small. I thought radius and smoothing should be kept low, and you're right, with a larger radius, it gives nicer results. Manual retouching is now more bearable.

Knowing the internals of the algorithms, do you think problem with fine details on the edge (the hairs) and at intersection of objects focused at different planes could be solved in an upcoming version ? Or maybe a combination of two rendering with different parameters could be the solution ?

Do you have any advices as regards the stack or the way the pictures have been taken to improve even more the process ?

Thanks,
g0b

g0b
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Post by g0b » 25.11.2009 16:07

Previous message was from me. Forgot to log in...

g0b

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Stas Yatsenko
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Post by Stas Yatsenko » 25.11.2009 17:11

There is an optical problem. Each hair when unfocused hides the background behind it. So I would suggest you to set lower aperture (F11-F16) and see if this would help. I've tried to change some internal parameters of the algorithm but the result is not better. So far we have no ideas how to get better results from this stack, sorry.

g0b
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Post by g0b » 25.11.2009 20:34

Hi Stas,

Thanks for your feedback.
I'm not sure a smaller aperture would help considering the very tiny depth of field, and my optical assembly (the real aperture is not what is written in the EXIF) but i'll try that.
I don't see how I could optically avoid out of focus overlapping parts to mask in focus ones...

Thanks !

g0b

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Stas Yatsenko
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Post by Stas Yatsenko » 26.11.2009 17:55

Smaller aperture gives smaller bokeh, I hope

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