Rendering Fire got cut off

[thhvfx]

Hi,

We ran into a problem with rendering fire got cut off. At first we thought that's container resize but we did check by rendering locally and it works fine. Anyone here ran into the same problem?

Thanks,

[Svetlin.Nikolov]

Hey,

Do you mean the grid is shrinking and parts of the fire are getting cut, or is the rendering sequence interrupted?

Cheers,

[thhvfx]

I figure out the problem. So basically some of my fire doesn't have Alpha match with RGB and my Vray renders setting have Auto alpha reside on. I turn Alpha reside off and the problem goes away. Here is what I like to know, some of my fire has Alpha match perfectly with RGB and some of them are not. Any reason?

Cheers,

[Svetlin.Nikolov]

Hmm, would it be possible to show an image of the difference? Thanks!

[thhvfx]

Sure, I will upload images tomorrow when I get to work.

Thanks,

[thhvfx]

Hi Svetlin,

Here is the rgb and alpha channel. Please take a look. My other fire was fine except 2 of them have the similar problem.

Thanks

[Svetlin.Nikolov]

The images attached are quite small, but probably what you mean is related to the Fire Opacity Mode option in the Fire rendering settings of Phoenix: https://docs.chaosgroup.com/display/...nderFire-Color

Cheers!

[thhvfx]

It's weird cause I'm using the same preset for all fire. But some of them have perfect alpha and some of them just not match alpha with rgb.

[thhvfx]

Actually I may figure out why. Probably because some of my fire got smoke and that generate the alpha and the one that not match alpha with rgb are the one don't really have smoke. I also turn smoke opacity to 0 to get the fire look more like fire instead of over exposure fire.

I will let you know if I find something else.

Cheers,

[Svetlin.Nikolov]

Indeed, this is expected if the Fire Opacity Mode is Fully Visible - there the fire has only RGB and no Alpha. However, if you are in a different opacity mode, it's something that needs investigating.

[thhvfx]

Hi Svetlin,

I was in Fully Visible mode. The problem why my fire got cut off is in the Vray render setting I have Auto reside to where the alpha is to make the file small and comper will have an easy time in compositing process later on.

I uncheck the Auto reside alpha and everything just works fine.

Cheers,

[Svetlin.Nikolov]

Ahuum, so this was it indeed. Glad it's working now! We need to figure a way to make all fire opacity modes easy for comping.