Point light inside Bottle does not "illuminate"

[ddolezal]

Good morning,


I have a question concerning a Point light source:
Downloaded the beer Bottle from the WebLibrary, placed it and put a Point Light (Scaled down to 2cm, Radius 1cm) inside the Beer Bottle.
I assumed that the light should Illuminate the liquid and the glass from the inside out - but it does not.
It only illuminates the ground plane a little bit.


Same thing with a Spotlight which I place "behind" the beer Bottle:
Shouldn't it illuminate the Glass and the Liquid?
Why doesn't illuminat it the glass from behind?


Shadow Quality 1, Ray Bounces 20, GI on, Caustics on, Product mode.


Do I miss something or how do I make my Bottle liquid to "glow" from the inside?


Thanks and best regards,
Dieter

[newoldschool]

Hello, Did you find a solution?

[INNEO_MWo]

Try to use a ground plane

[ddolezal]

@INNEO_MWo As I see it, we do have a ground plane in the Setup, as a certain Point Light  inside the bottle does illuminate the Ground plane - but not  the bottle from within.


So, we do not have a solution yet.


Regards,


Dieter

[INNEO_MWo]

Hello Dieter.

It depends on the liquid material inside of the bottle. This material doesn't cause any scattering. So on one hand you can add a scattering medium as a label material with a some opacity, but I guess this might be an overkill and takes too long to res up.

So I decided to simulate this with an advanced material and then the scene goes a lil out of hand.

It was fun to play with this. The scene was saved in GPU mode!


Hope the result an the attached KeyShot 10 scene might help you?!?

CheerEO
Marco

[DMerz III]

Light-sources in our real world, are not infinitely small like a point light is. You'll find point lights to illuminate objects using materials with diffuse channels better than objects with out one - such as transmissive or transparent materials -- at least not directly. A trick I've used in the past is to bounce 'illumination from a point light off of a surface to turn that into a reflection ray and then use that to illuminate transparent objects.

Think of it like a bounce -card.

Also think about what you're asking the engine to do here, you're putting a light source INSIDE the volume - we don't see this ability in the real world, light shining through a glass of beer is coming from outside the glass and from behind or from the side of the beer, and actually in some cases, it's coming from in front of the beer and we're selling light scattered as it's transmitting through.

The engine sees the liquid body as a shell - and the ray-tracing is going from the camera to the object, back to the light-source (the opposite of how a light ray acts in reality). So you're giving the shell of the liquid body very little chance to find the light source when you hide it inside the body of the liquid.

[ddolezal]

Thanks a lot for your input, Marco - I will try your setup asap.
And thanks DMerz III. - all what you are saying ist quite logical, but we did put light sources in the liquid in the ,,analog" Photostudio a couple of times, and this was exactly the idea our Director of Photography suggested to implement in Keyshot as well.
When it does not work because the constraints you mentioned, we will try your suggestions, which are more than welcome! Thanks!


Best regards,
Dieter

[Anindo Ghosh]

"The engine sees the liquid body as a shell"

This point by DMerz III gave me an interesting clue to play with this problem.

I carved a spherical hole into the "liquid" object and placed a slightly smaller sphere within that hole. Applying the Area Light material on this inner spere gives a nice "light inside the liquid" effect.

"It depends on the liquid material inside of the bottle"

This observation by INNEO_MWo provided a second avenue of investigation: The "Liquid Beer Bubbles" and the "Cloudy Orange Soda Bubbles" materials resulted in two very different glow effects.

I've attached the KSP in case anyone wants to play with it.

[newoldschool]

Thanks Anindo for all those great ideas!