What do you think about the light scattering in these clouds?

Started by blinkfrog, August 30, 2013, 01:10:19 am

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blinkfrog

Quote from: Oshyan on September 06, 2013, 04:26:23 pm
I think you're getting some nice results, but your reference picture is actually noticeably post-processed. Is it intentional that you use that? I would suggest using reference images that are as neutral (unprocessed) as possible, and with known exposure info as well (since exposure can have such a dramatic effect on the results, particularly with very bright and high contrast things like clouds/sky). Your basic shading concepts seem good though.

Thank you Oshyan. Yes, it seems incorrect to use just one photo for reference. I have seen some nice giant and dense clouds with low sun placed oppositely like in these photos several times in real life, but unfortunately I haven't had a camera with myself at these occasions.

And of course you are right speaking about the need of small rendering times. I'll try to move all calculations except for the first order scattering into GI stage. And although I'll lose quite resolution, on the other hand I'll be able to implement more advanced scattering that was unable to calculate at pixel-based rendering so may be the result will be more realistic. And of course other optimizations are needed too.

blinkfrog

Transferred all multiple scattering into GI-stage, improved scattering and also some optimizations done.
The sun is located behind the camera at the right side. ac3 - 34 minutes of rendering time, ac4 - 30 minutes.
ac4 - the same as ac3, but camera pitch angle is much less, so it is easy to see that GI-based scattering works bad at the distance due to low resolution and GI blurring. Also there are some need-to-fix bugs in air shadowing by clouds resulting in fake shadows at the lower side of clouds layer. This is due to some optimizations. :)

I'll try to implement "hybrid" algorithm to improve distant clouds view, performing the part of calculations at pixel-based rendering stage.

PabloMack

Quote from: blinkfrog on August 30, 2013, 06:56:23 am
Well, this isn't Terragen, it is my own engine, so I think "Image Sharing" isn't appropriate.


If you don't mind me asking, are you writing code in an HLL like C++ using OpenGL?

Oshyan

Some interesting stuff here, a few steps forward, a step or two back perhaps. ;) But great to see you continue to experiment with this stuff.

- Oshyan

blinkfrog

Quote from: PabloMack on September 24, 2013, 04:22:20 pm
If you don't mind me asking, are you writing code in an HLL like C++ using OpenGL?
Yes, it's C++ and OpenGL, how you surmised? But OpenGL used here by accident, as I haven't quick and small template with graphics, so I used my previous experimental project as the base. OpenGL is using here just for plotting graphics to screen. I'll rework it when will starting to sculpt GUI.

Quote from: Oshyan on September 24, 2013, 05:37:37 pm
Some interesting stuff here, a few steps forward, a step or two back perhaps. ;) But great to see you continue to experiment with this stuff.

Yes, I'll try to rewalk the "steps back" again before I'll go further :)

Hannes

Very interesting! I like the second one of your first set of images most. First I thought it's a reference image.
The latter one looks kind of cool, but reminds me of molten styrofoam. As Oshyan said, it's maybe not the ideal reference image.
Anyway I'm looking forward to your progress!

blinkfrog

Quote from: Hannes on September 25, 2013, 10:26:20 am
Very interesting! I like the second one of your first set of images most. First I thought it's a reference image.
The latter one looks kind of cool, but reminds me of molten styrofoam. As Oshyan said, it's maybe not the ideal reference image.
Anyway I'm looking forward to your progress!

Thank you. Although the 20km view can't show the features of my engine because the sun is located in front of camera, and the first order scattering in the clouds is most prominent. I think the most renderers can render the clouds in this case similar to my picture.

The higher camera-sun angles are the cases when my engine starts to show its special features. Various renderers do various approaches to render these cases and so mine.

For example, in this case you can see various orders of scattering together.
I made two versions of image, one is colored with various colors for various scattering orders: red is first order scattering, green is second and blue are third+ orders of scattering. Also some gray-blue comes from skylight.

Edit: BTW I fixed the air shadowing bugs. And also rendering time of that was 17 minutes.

Hannes


AP

The lighting and scattering is very nice. I like what you are doing. It would be great to see this coded into Terragen.

AP

I know you are busy with the erosion plugin but might there be any more work on this because i still think certain aspects of the clouds are very nice and still shows much potential.

blinkfrog

I plan to return to my clouds shading experiments in the future (very likely in a form of plugin for Terragen).

Dune


AP

That is just great to hear. I still admire the internal light scattering of the lighting and certain fractal aspects of the clouds look rather interesting as well.

Hannes

Ah, I almost forgot that! Yes, please return to your clouds!!!! They look so great!

Tangled-Universe

Definitely a big +1.

I think Matt would be interested to see your approach on light scattering :)