What realy is photon radiuss?

[bones_cg]

Can somebody tell me what is photon radiuss? :

[dalomar_cg]

Re: What realy is photon radiuss?

Where exactly are you looking? in the vray Sun?? Where matters because it could essentially describe a few different things.

Photons are essentially little particles of light that are shot out of lights. Years ago, Photons used to be a key component of high end rendering, but now they are really only used for caustic calculations.

[bones_cg]

Re: What realy is photon radiuss?

Ok, that is the part I undarstand,but in vray are option to change photons radius! Change photons radiuss with constant intensity? If one parameter is constant (intensity), what efect will give this radiuss change! Practicaly I don't see diferense! Mybe I do somthing wrong?

Thanks

[dalomar_cg]

Re: What realy is photon radiuss?

There are several different places where a radius will be used. I asked because it matters as there are differences between the various places where a radius is referenced.

I assume that you are asking about the value within the Sky dialog box, so will continue with that assumption. The photon radius will be the radius in which photons are emitted from the light itself (it has nothing to do with the size of the photons). This is used to control how much area will be used to generate the photons, and therefore how much of the scene the potential caustics effect can be seen as well as the density of photons.

There are two main reasons why this setting probably doesn't matter to you. First, its only going to affect your scene if you need photons, and the only reason you should need photons is caustic calculations. There are better, more efficient means of light calculation in V-Ray, so if you're using photons as a primary or secondary engine, then I would advise that you look into a few others. Secondly, there is no physical placement of a sun object since we are using just the default SU sun. This means that there's no exact way to determine where that radius will actually be generated from, which makes it practically impossible to determine the proper radius.

[bones_cg]

Re: What realy is photon radiuss?

Thanks, that is what I need to know!