Vertical water plane -> Waterfall (+animation)

Mohawk20 · February 04, 2009, 04:31:49 AM

Since the Ashundar Image of the Week contest theme is Crystal Clear, I was inspired to create a scene where the camera looks through a waterfall (from behind it of course). After the render completed I thought I made an obvious mistake thinking this would be possible, because the sky rendered black through the water (see first image below).

But then I did some post editing, and I found out the sky did render, it was just very dark (see second image below). This leads me to believe that if the Decay Distance is set higher than the slider's max (1000), the sky might become visible in the render without post work.
Did anyone else know about this?

JimB · February 04, 2009, 05:40:37 AM

Are the brighter white cloudy looking things actually clouds in the sky? If so, it seems odd that they'd render at almost expected brightness (probably half, but nowhere near as dark as the sky).

Are you sure it's not colour filtering through the water density causing the sky's atmospheric blue colour to darken, because of the greeny yellow default setting? Have you tried making the subsurface colour neutral grey?

PG · February 04, 2009, 06:02:30 AM

I didn't know you make the lake object vertical

Mohawk20 · February 04, 2009, 06:36:08 AM

The subsurface colour is a more blue tint than the default. But after rendering a few other tests I see that this effect might be some sort of reflection.

The sky does render though, if you set the distance high enough, but it doesn't look like this (yet).
I'll upload my next result when the render finishes.

Mohawk20 · February 04, 2009, 09:15:33 AM

Below images have very high Decay Distance. The first one has a value of 1e+008, the second one 1e+010.
The last one seems to do the trick.

So although the initial effect that lead me to this was probably only a reflection, it is actually possible with the right settings.
Now to get a more realistic shape to it...

old_blaggard · February 04, 2009, 10:54:27 AM

Cool!

Mohawk20 · February 04, 2009, 02:58:46 PM

Quote from: old_blaggard on February 04, 2009, 10:54:27 AM
Cool!

Yes, as it is natural mountain water

Below image has the plane resized a bit and I added a power fractal with billows noise, stretched to 10 on the y axis. It took 4,5 hours to render, but it actually does look pretty good... (sometimes the software still amazes me).
The Decay Distance in this one is 1e+009, which seems to be just as good as 1e+010.

So, everyone, get those waterfall scenes started!!

old_blaggard · February 04, 2009, 03:01:14 PM

Here's an idea - try feeding the water shader into the input port of a default shader, and then using a tweaked power fractal as an opacity function. You should be able to get trails of water suspended in space, which will look more realistic. You could also integrate some clouds to act as mist, and you would have an incredibly convincing setup.

Mohawk20 · February 04, 2009, 03:03:01 PM

Which is a very good idea. You should get started on it

I'll see what I can make of it...

Mohawk20 · February 05, 2009, 02:13:08 PM

Those clouds aren't a problem, but feeding the water shader through the default shader gave some problems, specially in combination with that opacity function.

It seems that the parts that stay opaque also stay black/dark in stead of clear/watery. And controlling the opacity is a lot harder than I hoped.

Are you having any luck with it OB?

Tangled-Universe · February 05, 2009, 02:22:31 PM

Cool work so far Mohawk

I guess you're using a plane-primitive with a watershader applied as surfaceshader?

The problem with the opacity might be due to TG2 still not being able to read grayscales from opacity. So its either fully opaque or fully transparent.
I can be mistaken, but I think this hasn't been fixed already.

Martin

old_blaggard · February 05, 2009, 03:06:00 PM

I haven't tried it yet and I probably won't have time to for quite a while.

Quote from: Tangled-Universe on February 05, 2009, 02:22:31 PM
Cool work so far Mohawk
I guess you're using a plane-primitive with a watershader applied as surfaceshader?

The problem with the opacity might be due to TG2 still not being able to read grayscales from opacity. So its either fully opaque or fully transparent.
I can be mistaken, but I think this hasn't been fixed already.

Martin

That's true, but all you need are black and white: black for no water, white for water. The problem is that is appears that the default shader is not allowing the transparency effect from the water shader to get through. I'm not exactly clear on how opacity is passed along the network, so perhaps feeding the default shader into the water shader instead of the other way around would preserve the transparency while allowing the opacity to do its thing.

Mohawk20 · February 05, 2009, 03:14:56 PM

I don't need grayscale, the black and white of a powerfractal can still make some pieces invisible while the rest stays visible (see below).
The problem is that using a default shader to apply the opacity effect kills the water effect, as you can see...

I'll try rearranging the nodes, (something I thought of before reading OB's post

If the transparency doesn't come through the opacity, let's hope it works the other way around.

If it does, we have a winner!
(I'll be waiting for that nobel prize

)

Tangled-Universe · February 05, 2009, 03:22:51 PM

Quote from: Mohawk20 on February 05, 2009, 03:14:56 PM
I don't need grayscale, the black and white of a powerfractal can still make some pieces invisible while the rest stays visible (see below).
The problem is that using a default shader to apply the opacity effect kills the water effect, as you can see...

Ok, you don't need grayscale, but since grayscales doesn't work it also implies that the opacity-function still isn't working properly and therefore could still be the reason of your problem.
You're probably right that it is something else but I would never rule it out though.

Quote from: Mohawk20 on February 05, 2009, 03:14:56 PM
I'll try rearranging the nodes, (something I thought of before reading OB's post
If the transparency doesn't come through the opacity, let's hope it works the other way around.

If it does, we have a winner!
(I'll be waiting for that nobel prize )

Can you show me how you set this up? I might be able to help?

Mohawk20 · February 05, 2009, 03:33:58 PM

It's pretty easy:
Create a plane, use settings: edge vector A= 0-1-0 , and Edge vector B= 1-0-1
Use any other size settings you like.

Go into the internal network and create a water shader and change Decay Distance to a value of 1e+009.
Plug the water shader into the plane's surface shader input
Create a powerfractal and plug it into the water shaders input.
Use a relatively small scale and perlin-billows as noise. Stretch the noise to 10 on the y-axis.

For opacity, use the already created default shader that came with the plane object. Copy the powerfractal and increase the size settings a bit. plug that into the opacity function input of the default shader.
Now, try to find out how to attach the default shader so everything works...