Card Shadows and God Rays

[WAS]

For some reason when I use a card to create shadows, there are zero god rays like if you use a cloud layer and image map.

I have the card hidden to camera, but visible to other rays, and cast shadows enabled. Is this just not possible without clouds?

[bobbystahr]

For some reason when I use a card to create shadows, there are zero god rays like if you use a cloud layer and image map.

I have the card hidden to camera, but visible to other rays, and cast shadows enabled. Is this just not possible without clouds?

you at very least need a thick atmo as it the reaction of the light with the atmo or cloud.

[WAS]

For some reason when I use a card to create shadows, there are zero god rays like if you use a cloud layer and image map.

I have the card hidden to camera, but visible to other rays, and cast shadows enabled. Is this just not possible without clouds?

you at very least need a thick atmo as it the reaction of the light with the atmo or cloud.

Oh, yeah. To clarify, I have a 0 falloff cloud layer matching the elevation of the card, with sharpness to 10, and played with all sorts of densities from 1 to 0.01 and just nothing shows. With a cloud layer, and same image map, or a PF, you'll get thick god rays with this sort of sharp edges atmosphere with even 0.05 density.

[Hannes]

I'm not sure if I get you right, Jordan. As far as I understood you're trying to create godrays by using a card with an image map or a PF.
I did a test. See images below. I tried the internal TG card object with an image map in the opacity slot, and as a comparison also an object with deleted faces to see if there's a difference between these two methods. Both objects create godrays.
Then I made the TG card invisible, and you can see clearly, that the godrays are still there. Of course they are less visible because there is a bright background.
Is this, what you're trying to achieve? Sorry, maybe a silly question, but did you check "receive shadows from surfaces" in the cloud's quality tab?

[Hannes]

A quick and dirty underwater setup (because this is what you want to achieve I assume?).
There's one TG card with a caustics image map in the opacity slot set to invisible that produces the caustics on the ground and the godrays. There's another card (cast shadows unchecked) with a reflective shader and a PF for displacement for the sea surface. The PF and the caustics don't match each other, but it's only for testing.

[bobbystahr]

A quick and dirty underwater setup (because this is what you want to achieve I assume?).
There's one TG card with a caustics image map in the opacity slot set to invisible that produces the caustics on the ground and the godrays. There's another card (cast shadows unchecked) with a reflective shader and a PF for displacement for the sea surface. The PF and the caustics don't match each other, but it's only for testing.

brilliant, what haven't I sussed this out...must be losing "little gray cells" heh heh heh

[WAS]

I'm mainly using procedural. I don't like fake image maps that don't match the actual waves, and generators are all but useless for a unique scene, and limit you to their vision of caustics, based on a swimming pool. Lol

And again, this setup doesn't produce god rays, so I'm confused. I a new water shader on this shadow card so it looks funny, need to redefine it.

[Hannes]

Sorry Jordan, actually I have no idea, what you want to do. Maybe you could describe your setup a little more detailed. The subject is, you can't create any godrays, right? So, what do you use as "godray maker"? A card with a procedural pattern? Above a localised cloud?

I just mapped a PF onto the card, and here they are. Godrays. I know, the PF doesn't look like caustics, but it's just to show, that it can be done procedural as well.

[WAS]

Not sure, than.

Like I already stated, it's the same approach done with my other underwater scenes, all with godways, utilizing a image map and clouds. If I swap that cloud for a card with my PF built off of water shader, there are no god rays. Even upping cloud edge sharpness to 200.

Usually I don't even use a density shader with the cloud for water volume, but even with one still no difference.

[Hannes]

Sorry, maybe a silly question, but did you check "receive shadows from surfaces" in the cloud's quality tab?

This is probably the first time, that I'm quoting myself . I just loaded your file, and what I wrote is exactly the thing you didn't do. Without checking this you'll never get godrays except by clouds themselves. So I activated it and additionally disconnected the density shader. I think it looks better without.

[WAS]

There it is. I thought I went in and checked that. Than again I was loading up 3 different projects and their subsequent incremental saves checking differences in a couple instances of TG.

Thanks for all the help. Feel rather stupid.

It's odd none of the god rays match the actual shadow cast on to the surface. They all seem slightly off center to their "highlights" on the surfaces. Unless god rays are actually only being seen right up against the camera, thus unable to see their highlighted patches.

[Dune]

Now add some color refraction by shifting the masks a bit and using different colors..

[WAS]

Now add some color refraction by shifting the masks a bit and using different colors..

Is there colour refraction underwater? I've never seen this. The surface of water lets through all frequencies of light. The rolls of the water simply refract all light in another direction, creating shadows.

Through water volume there may be different, with spectrum that scatter further, but considering what is let into earths atmosphere, it'd just be further blues and UV being scattered. Not sure that would be really noticeable without other light sources adding coloured light to the mix.

Also not sure what you mean by shift? I'm already having issues with TG's shadows appearing fake, and not matching any highlights on surfaces.

[WAS]

Additionally, do TG shadows not even grow? At 25 meters, the shadows scale with the height and stay tight, instead of cascading. IRL shadows would cascade out at a distance, grow larger, and more blurry. Especially off-center shadows the lightsource.

Also, I have visible to other rays disabled on both the surface, and the shadow map, but can't get the shadow map to stop projecting on the surface card. May be the transparency. Also can't seem to get any displacement to show with transparency and reflections. Even if I use just the reflection layer with the displacement shader, there seems to be no wave definition, even with disp at 20.

[Hannes]

I guess,  what Ulco means is the effect that you can see on underwater images that look somehow similar like chromatic aberration. Like white light refracted by a prism which shifts the base colors a bit.
Ulco did that before, but atm I don't know, how he did it.