Caustics making my scene darker

[Rob Burns]

I've recently started experimenting with caustics hoping they may add some subtle additional lighting effects. I was expecting them to only brighten the scene if anything, but to my surprise, when I enable caustics the rendering becomes darker in a lot of places, like the underside of balconies that are receiving only bounced light, and especially behind windows. I'm wondering if enabling caustics triggers some other part of vray's lighting to become disabled, like some portion of the GI calculations? Just trying to understand it better. Here are some examples.

Without caustics:


with caustics:

[Rob Burns]

Here is another quick example, note the lighting under the balconies is darker in the version with caustics.

without caustics:


with:

[Art48]

Did you set up your glass to not cast transparent shadows? AFAIK the caustics will do that part and oyu actually have to change your glass to get rid of the "fake" transparent shadowns since now the caustics do them.

[^Lele^]

If you turn caustics on, turn off "affect shadows" for transparent shaders.
Caustics will take care of that.

oh, as Art said above.

[Rob Burns]

Here is another version with 'affect shadows' off in all the transparent materials, it is still a lot dimmer behind the glass. I've set caustics subdivs are set to 6000 in both the sun and sky/dome light, and max photons is set to 6000 in vray, for a final rendering I'd set them higher. I'm wondering if this is more accurate than the fake transmitted light and I just have to adjust the glass transparency and scene lighting to get a better looking result? I'm looking for the most realistic way of rendering with v-ray (as close to an 'unbiased' renderer as possible), so I think caustics should be part of the image.

[Svetlozar Draganov]

Caustics are certainly more accurate than Affect Shadows but they requires additional tweaking and render time.
Affect Shadows in general produces a very nice result so most people doing arch-images prefer using it instead of Caustics and only use Caustics for effects that cannot be simulated with Affect Shadows like caustics of the water pool etc.

[Ihno]

Hi, dont know if this is the same but at least similar.
I've no refractive materials in the scene.
Domelight + 2 Vray Plane Lights. Vray 3.4.02
Am I doing something wrong?
Will send the scene to the support since the HDRI is too big for attachment.

Edit:Ticked ID is:#123825