Vray GPU dispersion, when to use??

[luisgamino2]

Hi Nikoleta Garkova

When should i use this option, i already did some research and in real life in physics glass, water and air material have dispersión in refraction, i'm rendering an interior space, should i use this option in just a normal glass Window, or it is only for jewelry (diamonds) in vray next this option was very slow, right now in vray 5 is not that slow, it render faster, it justs take a little bit more time, but what kind of advantages do a i see when i enabled this option???, sometimes i see a better reflection on floors when dispersión is on, but should i keep this option on?? Is not a waste of time using this option in glass Windows???

Do You think maybe with dispersión can i get a better reflection and refraction in glass material??? At least make this Window more realistic

Thanks in advance Best regards

[Muhammed_Hamed]

i'm rendering an interior space, should i use this option in just a normal glass Window, or it is only for jewelry (diamonds)

Hey luisgamino2

Don't use dispersion on glass of your windows, there is no need for that
Role of thumb is only use dispersion where it makes a visual difference, so always work with reference images
Dispersion exists in real life everywhere but this doesn't mean turning it on for every glass material, because it is only noticeable on things like Diamonds or a glass Vase. This is more about art than being as physically accurate as possible
So if your camera is close to a glass cup filled with water for exmaple, this should be a good example to use dispersion and usually the effect shouldn't be strong (never work without references)

Here is an example I used dispersion, and without this effect the glass on the jar would look fake

Do You think maybe with dispersión can i get a better reflection and refraction in glass material??? At least make this Window more realistic

probably not, it is just not ideal as this can affect render times massively, keep in mind that Vray uses spectral rendering (assigns wavelength to rays) to calculate this effect, hence it always has an impact on performance
Some people exclude this windows glass from direct lighting and GI , and some people don't use glass at all on their windows(to avoid issues or slowdowns)
If you do some testing on that, I would love to see. I hope this is helpful and let me know if you have more questions.

right now in Vray 5 is not that slow, it render faster, it justs take a little bit more time, but what kind of advantages do a i see when i enabled this option???

Very good to hear it has been fast in your testing. Vray gives artists great flexibility and tools that can achieve variety of things, because of how it is used in many industries from Archvis to visual effects and product design. And with this flexibility comes a bit of responsibility, you don't need to use every slider at hand. You usually focus on the ones you need for a specific look you are after

Best,
Muhammed

[luisgamino2]

Hi Muhammed Hamed

Ohh i see!!! Is just for few details, like vases for flowers or with water, in your example i can see this efect on the jar, it gives a Nice efect, thanks for the clarification and the example Muhammed

Best regards