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General => Terragen Discussion => Topic started by: Shigawire on December 20, 2015, 05:07:43 PM

Title: Arctic terrain - glittering snow shader
Post by: Shigawire on December 20, 2015, 05:07:43 PM
Hi. I've had TG3 for over a year now, but this is my first proper project that I have done with TG3.
The amazing Erosion plugin got me excited and made me jump back in. :)

So I made a simple mountain with some erosion.. then I put the muntain on hold as I started focusing on getting a "snow shader"
The thing I had the greatest trouble with was the glitter. I finally found a solution thanks to some good tips.

I used a "default shader", and plugged a power fractal into "reflectivity" - an inverted "voronoi ridges" noise (so they look like white dots). I didn't want too much of a distribution, so I increased color offset slightly, and put in a Color Adjust Shader to constrict the colors further. The trick to force the sparkles to come strongly through the blurry Anti-Aliasing was (as someone tipped me about on the facebook page) to increase the Specular value of the Default Shader to insane levels, as that apparently plays a role in the AA's priorities. Specular value changed to 50.

This is a very high res picture, 12.6 mb.

Let me know what you think.
https://www.dropbox.com/s/83brx1rcb94fgdx/Arctic_closeup_10.tif?dl=0
Title: Re: Arctic terrain - glittering snow shader
Post by: Kadri on December 20, 2015, 05:17:53 PM
Nice.
It is a 16 bit TIF kinda HD image.You can easily convert it to 8 bit and post it here as a JPG or PNG image.
Standard monitors can't show 16 bit images anyway.
Title: Re: Arctic terrain - glittering snow shader
Post by: Shigawire on December 20, 2015, 05:32:50 PM
Quote from: Kadri on December 20, 2015, 05:17:53 PM
Nice.
It is a 16 bit TIF kinda HD image.You can easily convert it to 8 bit and post it here as a JPG or PNG image.
Standard monitors can't show 16 bit images anyway.

Oh I didn't know that. :)

I will do an 8 bit next time.
Title: Re: Arctic terrain - glittering snow shader
Post by: dandelO on December 20, 2015, 06:04:45 PM
Hi, Shigawire, looks nice, I've battled with sparkles a bit and, if you don't mind, I'll add a few tips that I've found to be very effective for glittering up some snow...
You might find it more intuitive to keep the specular 'Reflectivity' value at '1' and use a higher 'Index Of Refraction' value, higher than the regular '1.5' in a Default Shader. Maybe 2 to 3, use small increments. That'll should give an outstanding highlight.
You'll however notice the band of sparkles to be very tight and only appearing near the direct light source of the Sun, you can loosen that up and spread it faaaaaaar and wiiiiiide across your surface by increasing 'Specular Roughness'. I've never went higher than a value of '1' for roughness since small increments here can also make a big difference in highlight spread. The slider limit is '0.8' but you can input higher values manually into the text field.
It's likely you'll now see an entirely glossy surface, visit the sparkle fractal's Colour tab and, if 'High Colour' is checked, reduce 'Colour Offset'(if Low Colour is checked, raise offset), to reduce your sparkles back down to little pin-pricks of light again.

To me, after a ton of experimentation, along with lots of tips and contribution with others here on this, among many other subjects on managing reflectivity, it really makes for a much more versatile, and easier to control, spread of highlights, from a tight band, to a full-screen scattering across the entire frame.  :)
Title: Re: Arctic terrain - glittering snow shader
Post by: bobbystahr on December 20, 2015, 07:38:52 PM
Quote from: dandelO on December 20, 2015, 06:04:45 PM

It's likely you'll now see an entirely glossy surface, visit the sparkle fractal's Colour tab and, if 'High Colour' is checked, reduce 'Colour Offset'(if Low Colour is checked, raise offset), to reduce your sparkles back down to little pin-pricks of light again.

To me, after a ton of experimentation, along with lots of tips and contribution with others here on this, among many other subjects on managing reflectivity, it really makes for a much more versatile, and easier to control, spread of highlights, from a tight band, to a full-screen scattering across the entire frame.  :)

cool, I sorta knew this but copied it to my technique folder anyhow...thanks for doing the leg work
Title: Re: Arctic terrain - glittering snow shader
Post by: WAS on December 20, 2015, 10:45:34 PM
You may also try to use DandelO's suggestion in two parts, using a Distance Shader plugged into your view point. This allows you to create nice close up speckles, with nice far (inverted distance shader as mask) speckles for a perfect balance.
Title: Re: Arctic terrain - glittering snow shader
Post by: Shigawire on December 20, 2015, 11:59:49 PM
New render up.

I am happier with this. But there is one thing bothering me. That's the dark dots in shaded areas. I am certain it's caused by the same reflection shader that makes the glitter... but unaware of how to fix it.
Title: Re: Arctic terrain - glittering snow shader
Post by: Dune on December 21, 2015, 03:20:15 AM
May have to do with the combination of (new) sparkles settings and translucency. Or you may have added something under the (translucency of the) default shader. The sparkles are also too evenly spaced, IMO.
Another idea may be to add some distance, tiny fake stone and PF masked default shader's reflectivity. The fake stone (5mm or so) will act as tiny dot, the PF for a more varied distribution.
Title: Re: Arctic terrain - glittering snow shader
Post by: Shigawire on December 21, 2015, 03:42:57 AM
Quote from: Dune on December 21, 2015, 03:20:15 AM
May have to do with the combination of (new) sparkles settings and translucency. Or you may have added something under the (translucency of the) default shader. The sparkles are also too evenly spaced, IMO.
Another idea may be to add some distance, tiny fake stone and PF masked default shader's reflectivity. The fake stone (5mm or so) will act as tiny dot, the PF for a more varied distribution.

So, you think it's best to make the distribution of sparkles less even, and more spread? I'll give it a try.
I haven't tried Fake Stones yet, but I might give it a go if it looks better.
Title: Re: Arctic terrain - glittering snow shader
Post by: Dune on December 21, 2015, 03:45:42 AM
Tiny fake stones smake very crisp, facetlike masked areas, almost like crystals (especially if you fractal-warp them, but that is overdoing it). No good for direct displacement, but good for reflections.
Title: Re: Arctic terrain - glittering snow shader
Post by: Shigawire on December 21, 2015, 08:17:52 AM
Quote from: Dune on December 21, 2015, 03:45:42 AM
Tiny fake stones smake very crisp, facetlike masked areas, almost like crystals (especially if you fractal-warp them, but that is overdoing it). No good for direct displacement, but good for reflections.

Just got home from work, might give that a go. I just want to figure out the dark spots first.
Title: Re: Arctic terrain - glittering snow shader
Post by: Shigawire on December 21, 2015, 08:26:56 AM
Quote from: Dune on December 21, 2015, 03:20:15 AM
May have to do with the combination of (new) sparkles settings and translucency. Or you may have added something under the (translucency of the) default shader. The sparkles are also too evenly spaced, IMO.

I figured out what did the dark spots. Having a crazy high reflectivity combined with high IOR (2 to 3) made the snow reflect the blue-sky in the shadow spots. To fix, I just drop IOR to water levels of 1.33 or simply turn reflectivity back to 1 as someone suggested. The reason why I pushed the reflectivity into very high levels is that the AA blurs the glitter too much. And overshooting the reflectivity levels confounds the AA and makes it not blur glitter too much.
Title: Re: Arctic terrain - glittering snow shader
Post by: Tangled-Universe on December 21, 2015, 08:31:58 AM
I noticed you're (probably) using Mitchell-Netravalli (MN) as AA-filter, is that correct?
Noticed dark circles surrounding your reflective highlights, which is an indicator for the negative lobe in the AA-model of MN.
If so and you'd like to prevent that I would suggest to use Catmull-Rom and a bit higher AA or just use the default cubic filter.
Title: Re: Arctic terrain - glittering snow shader
Post by: Shigawire on December 21, 2015, 08:35:02 AM
Quote from: Tangled-Universe on December 21, 2015, 08:31:58 AM
I noticed you're (probably) using Mitchell-Netravalli (MN) as AA-filter, is that correct?
Noticed dark circles surrounding your reflective highlights, which is an indicator for the negative lobe in the AA-model of MN.
If so and you'd like to prevent that I would suggest to use Catmull-Rom and a bit higher AA or just use the default cubic filter.

Correct sir. Couldn't expect Martin Huisman not to have a trained eye for this. ;) I wanted an AA filter that does sharpness, but I'm never content with any of the choices. I'll try some of the others, cheers.
Title: Re: Arctic terrain - glittering snow shader
Post by: Tangled-Universe on December 21, 2015, 08:40:27 AM
Ha ok, seems you know me better than the other way around ;)
Title: Re: Arctic terrain - glittering snow shader
Post by: bobbystahr on December 21, 2015, 09:22:20 AM
Quote from: Tangled-Universe on December 21, 2015, 08:40:27 AM
Ha ok, seems you know me better than the other way around ;)

a Dune the novel fan for sure....
Title: Re: Arctic terrain - glittering snow shader
Post by: Shigawire on December 21, 2015, 09:51:42 AM
Quote from: bobbystahr on December 21, 2015, 09:22:20 AM
Quote from: Tangled-Universe on December 21, 2015, 08:40:27 AM
Ha ok, seems you know me better than the other way around ;)

a Dune the novel fan for sure....

Guilty. :P
Title: Re: Arctic terrain - glittering snow shader
Post by: WAS on December 21, 2015, 02:52:19 PM
Quote from: bobbystahr on December 21, 2015, 09:22:20 AM
Quote from: Tangled-Universe on December 21, 2015, 08:40:27 AM
Ha ok, seems you know me better than the other way around ;)

a Dune the novel fan for sure....

We all know us fans tried to create Arrakis at some point...
Title: Re: Arctic terrain - glittering snow shader
Post by: Shigawire on December 21, 2015, 03:36:08 PM
Quote from: WASasquatch on December 21, 2015, 02:52:19 PM
Quote from: bobbystahr on December 21, 2015, 09:22:20 AM
Quote from: Tangled-Universe on December 21, 2015, 08:40:27 AM
Ha ok, seems you know me better than the other way around ;)

a Dune the novel fan for sure....

We all know us fans tried to create Arrakis at some point...

Yeah, alas only Wiwine got close to that. I did manage to make a decent desert scene in World Machine, but only the geometry, and nothing beats a full planet that you can zoom a camera from orbit to surface seamlessly. So I haven't given up on it. :)
Just need to learn a lot more stuff first!
Title: Re: Arctic terrain - glittering snow shader
Post by: WAS on December 21, 2015, 03:40:45 PM
My only attempt. Friend rendered it for me without a BG so I could edit in PS.

(http://s30.postimg.org/4deik4y9t/image.jpg)
Title: Re: Arctic terrain - glittering snow shader
Post by: Shigawire on December 21, 2015, 03:47:17 PM
That's awesome. Though the real trouble begins once you want to do the dunes close up. :) Parabolic dunes, star dunes, etc. And they need to have a maximum slope on the leeward and windward side. Wiwine really came pretty damn far with his stuff. I think I can learn more from his methods. But it's way above my head... (currently) - need to brush up and get some more in depth trigonometry understanding.
Title: Re: Arctic terrain - glittering snow shader
Post by: WAS on December 21, 2015, 04:11:00 PM
Quote from: Shigawire on December 21, 2015, 03:47:17 PM
That's awesome. Though the real trouble begins once you want to do the dunes close up. :) Parabolic dunes, star dunes, etc. And they need to have a maximum slope on the leeward and windward side. Wiwine really came pretty damn far with his stuff. I think I can learn more from his methods. But it's way above my head... (currently) - need to brush up and get some more in depth trigonometry understanding.

Yep, I can't get dunes, or snow drifts to look that great for both my sand shaders and snow shaders.
Title: Re: Arctic terrain - glittering snow shader
Post by: Shigawire on December 31, 2015, 12:57:30 AM
Is there a way to tell a specific reflection shader to only reflect the sunlight, but to ignore the bluesky environment?
Or, say, a falloff controller for the reflectivity, based on direct lighting. So that reflection would only be happening in surfaces hit by the direct light (sun-light or other).
I just need a simple answer.
Title: Re: Arctic terrain - glittering snow shader
Post by: TheBadger on December 31, 2015, 01:11:50 AM
nice snow :)
kinda rather like the large image of the first post better though. I like how you can scroll/zoom into it. Like that on cgsociety too. meh, just jabbering, cool image anyway.
Title: Re: Arctic terrain - glittering snow shader
Post by: Oshyan on December 31, 2015, 03:55:19 AM
No, you can't control reflection in those more complex ways.

- Oshyan
Title: Re: Arctic terrain - glittering snow shader
Post by: Dune on December 31, 2015, 03:59:43 AM
Unless you render out a mask from a hard-lit landscape, and project through render camera.
Title: Re: Arctic terrain - glittering snow shader
Post by: Shigawire on December 31, 2015, 04:31:48 AM
Thank you for the answer Oshyan. :)