VRay Light not renderable but to illuminate liquid in glass

[branskyj]

Hi all,

 

sorry for the "yet another such question" but I couldn't find a solution online.

 

I am modelling a bottle with rum inside and have gotten to the lighting stage. I have a VRay Camera pointed straight at the bottle with rum liquid inside and a VRay Light placed behind the bottle shooting at the bottle (and the camera). I do get a nice effect if the light is visible, if I make it invisible the liquid inside the bottle gets illuminated but in a more unpleasant way (it's a more uniform illumination which is not what I am after).

 

So my question is- can I keep the light visible but not renderable ( I don't want to see the bright rectangular in the render).

I wouldn't be asking if it was for a still image but the output should be video.

 

Cheers.

 

Cheers.

[Ismael]

http://help.chaosgroup.com/vray/help/150SP1/light_params.htm

 

"Invisible - this setting controls whether the shape of the VRayLight source is visible in the render result. When this option is turned off the source is rendered in the current light color. Otherwise it is not visible in the scene. Note that this option only affects the visibility of the light when seen directly by the camera or through refractions. The visibility of the light with respect to reflections is controlled by the Affect specular option."

[branskyj]

Thank you Ismael.

The more I think about it the more I realize I will have to achieve the result in post with a mask.

I like how I see the light through the glass and liquid inside but I don't like how the light is visible on the sides if the glass (it's a rectangular shape light).

I will use the wire color pass I guess and do it in post.

 

Cheers for the help, mate.

[Tommy L]

I have experience in this in both the real world and cgi.

Just so you know, the bottles you see in print ads are heavily retouched. They are also shot in multiple conditions, (one shot for the label, re-light for the glass, re-light for the cap etc).

The photographer will usually adhere a reflective surface, like aluminium foil, to the back of the bottle to get some action in the liquid.

In CGI you will need to have something happen both behind and in front of the bottle. The fluid itself is pretty much transparent, just a basic color. The glass is where the magic happens. Its going to be a balance of reflection of whats in front and refraction of whats behind, then some hot glancing angle light, lots of rimlight. You'll need a clear idea of what you are trying to acheive, or you'll run around in circles.

Without seeing your shot its hard to give specifics, but dont be afraid to have your lights visible. Using gradient ramps in visible lights is going to be a useful tool. Rendering a second pass to get your transparency will help you adjust stuff in post. I dont think you'll need to do condensation/ice particles for rum... thats the hardest part so you are getting off easy!

[branskyj]

These are all awesome ideas, Tom.

I am definitely going to try the gradient ramps in the lights idea and maybe even try attaching an "aluminium foil like" object behind the glass.

It's a shame I have to wait till Friday since they put me on a different project today. But I will post an image if I get permission from work.

 

Thanks mate and have a nice week.