[JorisMX]

Hey Guys,

long time no see !

The job I'm currently working on is a product render like we have seen here so often.
A bottle with liquid, lables a cap etc.

I have modeled the glas-fluid with the fluid inside a massive glass technique that has been discussed here several times. So far so good. Render looks just the way I expect and everything is great...

However... I have activated alpha and made sure not to tick opaque. Still the alpha channel is opaque.
There is an Emitter behind the bottle but it is hidden from cam and doesnt show up in the alpha. Still I dont see any transparency in the alpha.

It's been a while since I last used maxwell. I'm probably forgetting something very simple.

I found this thread btw thought that meant i wouldnt have any problems getting a different background behind my bottle renders using a correct alpha.

cheers
Joris

[Bubbaloo]

Can you turn off the emitter and run a quick alpha render?

[JorisMX]

yeah, still opaque alpha for the bottle

[JDHill]

Here are some quick tests that may shed some light on your scenario. First, with nothing hidden to camera:

• 

Next, with emitter hidden to camera:

• 

Next, with emitter hidden to camera, and hidden to reflections/refractions:

• 

[JorisMX]

Thx JDHill that looks like it makes sense.

I guess I will have to render an extra pass for the alpha then, because I am "using" the reflections the emitter makes and can't just turn them off for the main render. Will try this and let you know if that fixed it.

thanks!

[JorisMX]

Okay, yeah this isn't working.

I tried turning off the environment, turning off the emitter completely. Also tried turning off dispersion. No dice.
Looks like I cant get alpha from the material at all.

I will do a simple test over the weekend with a simplified scene.

[JDHill]

If you want to upload the MXM or the scene, we can take a look.

[Mihai]

What isn't working exactly? The alpha is still not transparent?

[JorisMX]

Yes Mihai. I'll post some materials on the weekend

[kami]

Did you try to hide the emitter with a BSDF?
Add a BSDF to your layer with opacity black, ND = 1 and roughtness = 0
Not sure if this would work though ...

[JorisMX]

what really put me off is. I deactivated all emitters and the environment.
So in my logic the issue can only lie within my materials or the meshes.

I'll post some soon. Gotta make Dinner now

[choo-chee]

first, JD - thanx for the test, it revealed a trick I needed long ago (hide emitter from glass !), thanx again.
Second - the problem may be that I found that some materials (old ones... like vividAGS if I'm not mistaken and other good old MXM gallery stuff)
render with opaque alpha, always. Don't know why. Or you have faces in the mesh that are still being shaded by another material.

[Mihai]

Those materials don't use Transmittance, hence the Hide to refractions won't work.

[JorisMX]

So I am getting proper alpha on the bottle now. Fluid still renders opaque and I have an idea why that might be.
I was using an overly bright emitter behind the bottle and had the attenuation set a bit strong.

I think the material editor just crashed on me in cinema after doing some wild tweaking :/
This is slowly starting to come together though. I'll come back with news once I worked on the fluid and its attenuation.

I'll see if I'm allowed to post some renders once the client is happy