Daydreaming on shadow catcher

Started by uuderzo, July 14, 2020, 08:36:32 am

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WAS

How interesting Kadri! Great thinking, thanks for sharing.

uuderzo

Quote from: Hetzen on July 15, 2020, 01:41:22 pmI suppose to make the effect more accurate, you could render a few shadow masks of the sun through it's arc of a day, add together, then divide by the number of images used. I guess that could simulate what would happen with temperatures.

But to be honest, the effect you've rendered looks like a fairly good representation of a snow drift. Using the Smoothing Effect in a Surface Layer, should knock out some of the lower octave noise.
I added more noise in the snow accumulation area (sorry I didn't know it is called drift) to add some detail and make it slightly different from the surroundings. Without, it looked weird to me.
My target was to simulate the snow accumulation brought by wind. This is the reason that made me initally think about shadows.

WAS

I had another thought, though I haven't attempted it yet, but it really leaves you with just one angle of approach, a vector export would give you sides, which than you could use as masks in PS etc. You could than "retain" the rock/object on a side, and then all others blur it out, and adjust intensity and would assentialy create soft buildup around the object leaving one side intact. You'd have to use the "one side" mask to mask the Y data and blur out the rest I'd imagine.

uuderzo

This is another approach for a single render result.

I decoupled the terrain by creating an heightfield then rendered it again shifted and smoothed. Looks like this is the only way to break the transformation chain up to the upper node. I still have some issues in the mixing part because the merger if set to "highest" seems to honour the highest displacement but color don't seem to follow the same logic, as you can see the white appears also on gray stones sometimes.

Dune

If you create your stones from a PF (or voronoi blue node setup), so you have soft white dots on black, and use a compute normal to blow them up laterally after initial displacement in Y, you could try using the initial (dot) masking, shifted half a meter or so by transform shader for snow pile-up mask. But you need one-size stones for that or the distance won't fit all.

Hetzen

I think the issue with the Merge Shader in this case, is that the colour mapping has to adjust to new polys being created.

A more expensive, but way crisper approach, would be to put your snow surface on a planet sized sphere and your stones on the planet (or vice versa). That way you would have proper intersection between the two texture/displacement surfaces.

WAS

Quote from: Hetzen on July 17, 2020, 09:46:21 amA more expensive, but way crisper approach, would be to put your snow surface on a planet sized sphere and your stones on the planet (or vice versa). That way you would have proper intersection between the two texture/displacement surfaces.

Yeah I mentioned that above, though with a plane. It would give you the best realistic result when coupled with SSS to if not for the totally broken shadows.

uuderzo

Quote from: WAS on July 17, 2020, 02:02:04 pm
Quote from: Hetzen on July 17, 2020, 09:46:21 amA more expensive, but way crisper approach, would be to put your snow surface on a planet sized sphere and your stones on the planet (or vice versa). That way you would have proper intersection between the two texture/displacement surfaces.

Yeah I mentioned that above, though with a plane. It would give you the best realistic result when coupled with SSS to if not for the totally broken shadows.
Sorry what stays for SSS?

WAS

Quote from: uuderzo on July 17, 2020, 02:50:06 pm
Quote from: WAS on July 17, 2020, 02:02:04 pm
Quote from: Hetzen on July 17, 2020, 09:46:21 amA more expensive, but way crisper approach, would be to put your snow surface on a planet sized sphere and your stones on the planet (or vice versa). That way you would have proper intersection between the two texture/displacement surfaces.

Yeah I mentioned that above, though with a plane. It would give you the best realistic result when coupled with SSS to if not for the totally broken shadows.
Sorry what stays for SSS?

Oh sorry, yeah SSS is kinda confusing cause we also use it for Simple Shape Shader, but I meant the Subsurface Scattering Effect of the Glass Shader under PT renderer. However similar settings can work under standard renderer. With the standard renderer and pseudo-subsurface effects, the shadows aren't broken.

Hetzen

I think planes makes things simpler certainly, you don't have to adapt to curvature in the projection.

WAS

July 17, 2020, 06:00:52 pm #25 Last Edit: July 17, 2020, 06:04:26 pm by WAS
Quote from: Hetzen on July 17, 2020, 05:43:29 pmI think planes makes things simpler certainly, you don't have to adapt to curvature in the projection.

It is, and I think I thought I was having issues with it but turns out it's just a issue with the glass shader in standard render. Corner of the renders, part of the glass would be very dark, almost look as though it wasn't there. I tried 360 degrees optimal crop but didn't seem to do anything, so not sure what was going on there.

In the mean time I switched back to the basic default shader snow, and played with some stuff.

Here we have buildup of terrain, and the fake PF based rocks. Notice more "untouched" snow from melt on the right/east (and towards camera; Translation 0.3, 0, -0.1) side following same result for rocks. The terrain snow buildup may look better with more extreme offsets. I'm also attempting to mask, and offset slopes as well though not positive it's working as desired.

Hetzen

July 17, 2020, 06:58:58 pm #26 Last Edit: July 17, 2020, 07:08:44 pm by Hetzen
Yeah that works great. It's tough to get a softened version to intersect well.

Maybe a Bias Scalar on your shadow displacement to curve out the black into the white a little more softly.

WAS

Quote from: Hetzen on July 17, 2020, 06:58:58 pmYeah that works great. It's tough to get a softened version to intersect well. Maybe a Bias Scalar on your shadow displacement to curve out the black into the white a little more softly.

I haven't tried but from how the layering of the meshes work I think the only real fix beyond "translucency" in default shader is subsurface scattering, whether pseudo or not. That way you can get that melt transmission a little better defined.

Seems the Default Shader even has it's issues too. At a distance the translucency effect becomes hard and noticeable. Wonder how that could be helped.

Hetzen

I was thinking more of the displacement of the snow layer. There's a hard line where the drift starts. It maybe softened out either with the gamma in the image map? Or possibly a Bias Scalar with a low value like 0.1 feeding the displacement?

WAS

Oh I see, yeah that's the floor of the rock shader, I think a soft clamp would fix that.