Arnold Q&A

[cheeseburger]

Hi SantOs,
Do you have to apply it to a pass or something and then dial in the lights ?

[sant0s]

yea, add them to the "Volume Shaders"-Tab.
The fog shader does not need to be specified by a light source, but the Volume Scattering needs a light source (spot or quad, Skydome and Distance Light will not work).

[Draise]

Um.. I have a question (I'm a newbie, and after much thought, I think it's still worth while investing time and effort into SI for a while yet - with Arnold and Redshift, still competitive).

So...How do I get volumetric lights in Arnold?

I have been trying to add the pass Volume Scattering attribute with the lights with Volume activated, but I get an empty scene, no glowing lights. I've tried nearly all the lights - and I can't get it to work. I've tried modifying the Volume Scattering operator in the passes, but nope, density does nothing. What could I be doing wrong?

Can someone please explain to me a step by step process to get volumetric lights? Sorry for being a noob....

[Draise]

There we go, just don't mix Fog with Volumetrics, one will cancel the other. Then that pass won't work... till you make a new pass with one or the other.

[sant0s]

when rendering a tree/forest and the leaves are cut out by alpha, its rendering amazingly slow compared to use real geometry only.
is there a cheap trick or something to speed that up?
or is trancparency general very slow?
thx!

[sant0s]

quick answer to myself: change alpha map from .jpg to .tif (or another lossless format) and posterize that there are only 2 values, black and white. gave me up to 3 times faster renderings.
i should have known that, i know ;).
the white in the .jpg was not 100% white, so everything was a tiny bit transparent I guess, that was increasing rendertimes.

[Bullit]

Arnold-Multi ASS Exporter Softimage

[theboykidney]

Have ice emission with particle as blob type. Any special trick to get this working with Arnold? what kind of shaders should I be using?
cheers...

[Dwindleflip]

Does arnold have a way to displace geometry that is not a subdiv surface? It seems you cant use it for displacement on regular polygon models.

I'm finding it difficult to near to impossible to make something as simple as a brick wall with displacement due to subdiv texture warping and the lack of regular polygon displacement (non subdiv)

[Rork]

Doesn't "Subdivision Iterations" and "Autobump" do the trick?

Otherwise, post some examples.

oh... be sure to set a Arnold property on the object.

[sant0s]

do I have to add a vector_state with Normal Vector to the tangent of the sta_vector_displacement?
If I do not add the vector state, the displacement is becoming lean.

It works, but wonder if that is the normal way to add a dispalcement

Take a standard grid with no subD's, add the property with for example 8 iterations and add a noise shader to the color of the displacement.
the displace will be forced to a direction.
if I add the vector state with the normal vetor choosen, its pointing up... is that the correct way?

and like rork said, add the property to your object and increase the iterations, that does the trick.

[Rork]

you have 'normal' displacement https://support.solidangle.com/display/ ... splacement
and vector displacement https://support.solidangle.com/display/ ... splacement

There's still a sta_displacement node in SitoA, but that's for backwards compatibility only.

The sta_vector_displacement node has tangent built in.

There's the support portal guys https://support.solidangle.com/

Use it wisely ;-)

[sant0s]

you have 'normal' displacement

are you sure?

Use it wisely ;-)

yea, thats why I wonder about the Displacement.
I read on the SolidAngelSite, that it will be removed, the old displacement...

[Rork]

In previous versions of SitoA displacement was a node, like wit MR. This was changed later into a property that you add to the object.

The old node is stil there for older scenes that were built wit that version of SitoA.
Wit the new workflow there's no need for the displacement node anymore.

[sant0s]

okay, I understand - but, I do not get, how than to use the sta_vector_displacement correctly

I attached a picture to clearify what I mean.

greetings

[Rork]

I think you're misreading the info on the vector node.
In your example a simple displacement would be just fine, no need for the sta_vector_displacement node.

The node expects tangent space vectors, and I'm not sure converting noise data into color will just work like that.
What the node expects to get is data from sculpting apps like ZBrush, Mudbox and alike. With that information you can displace the geo more than just in height, like with basic displacement.
Unless you're after a specific type of effect that displacement can't give you?

Hope that helps,

rob