Ray Traced Shadows in clouds/atmosphere

[reck]

When do you need to turn on ray traced shadows in the atmosphere and clouds?

I read somewhere that you need it turned on in the atmosphere if you want terrain casting shadows onto clouds, but I would have thought it would need to be turned on on the clouds settings not the atmospheres.

What about clouds casting shadows onto clouds below, do you need rts for this?

[Tangled-Universe]

You ONLY need Raytraced Shadows when the terrains casts shadows into either the atmosphere or onto the clouds.

In some cases, when using quite extreme or complicated displacements for example, you'll need to switch on raytraced shadows in the atmosphere node.
When you're rendering low-level clouds, in a canyon for example, with terrain casting shadows on the clouds then you'll need to switch on raytraced shadows in the cloude node.

That's the rule of thumb more or less

Martin

[reck]

So if I have a high altitude mountain poking up over a sea of clouds I could turn ray traced shadows on for the cloud layer and the mountain would cast a shadow onto the clouds? So if I turned rts on in the atmosphere tab in this example what would it do? Would it create a shadow between the mountain and clouds where there is just open sky?

[PorcupineFloyd]

Or if you want to render a sun hidden behind a mountain for example. It will result in casting visible rays in the atmosphere and will effectively hide the sun behind the mountain.

[reck]

Or if you want to render a sun hidden behind a mountain for example. It will result in casting visible rays in the atmosphere and will effectively hide the sun behind the mountain.

You need rts turned on for this? I thought you could get sun rays without having to use rts.

[Tangled-Universe]

You're thinking too much in exceptions.

The way I said it, is the way it is.
And yes, if mountains are poking over a see of clouds you'll have to use rts in the cloud node, not in the atmosphere.
And Porcupine is right about his example.

You should also be able to get rays without rts, but when more accurate calculation/shadows is necessary then rts comes in for rts in atmosphere.

Martin

[reck]

OK thanks guys.

Things take A LOT longer to render with rts so I wanted to be clear when I should use them. Don't want to be waiting for days for something to render because I turned on rts and I didn't need to.

[Tangled-Universe]

OK thanks guys.

Things take A LOT longer to render with rts so I wanted to be clear when I should use them. Don't want to be waiting for days for something to render because I turned on rts and I didn't need to.

You're welcome

This also accounts for GI surface details. That function is also rarely needed and in many cases triples (or even worse) the rendertime.

[reck]

This also accounts for GI surface details. That function is also rarely needed and in many cases triples (or even worse) the rendertime.

..and this should be used when your camera is close to the ground right?

What difference does it make turning it on, when testing in the past I never noticed much difference with it on or off.

[PorcupineFloyd]

As far as I recall you really need some complicated displacement at a close range in order to have more detailed shadowing on those displacements.