Photons rule!

[Metin_7]

Hiya,

Just wanted to thank Vlado for the photons. I'm finally busy discovering one of the last VRay secrets for me: the power of using photons for secondary bounces. Looks great with the right settings: smooth, blotchless and very nice GI shadows and color bleeding.

I also want to thank Goncalo for his valuable tips, answers and settings in various topics around this forum. I learned a lot from that, together with Vlado's basic guide to photons. Goncalo, you definitely are the Photon King! Soon in a theatre near you: "Lord of the Ray part 3: Return of the Photon King", featuring Goncalo.

Cheers guys,

Metin

[J_Bug]

hear hear

--Jon

[Metin_7]

I also learned a lot from MetroBerlin's additional feedback on top of Goncalo's info.

Cheers,

M7

[GoncaloP]

[metroberlin]

[Metin_7]

[Psy]

Anyone willing to take what they have said and condense it down into something more readable and understandable for us non-engineer people?

Not trying to be rude, but I can't make heads or tails of what GoncaloP has said in settings vs. what MetroBerlin says and does.

[GoncaloP]

Hey I m not an engenier either, I m an architect

Photon map is not easy to explain, and there are a lot of ways to achive good results with it...

I will try to resume it in a simple way I hope...

Max density - Define a grid or mesh where Vray will look for photons;
Search dist - it blur the photon in a portion of the scene, a good number is 2 - 5 times bigger than max density.

(This settings are scene and unit dependent, you will need to define it acordingly to your model units.)

Max photons - this number will estimate an aditional number of photons, from the already traced photons, if you want... a kind of interpolations in irradinace map.

Retrace treshold - this number defines a portion of the scene that will be computed by direct computation in secondary bounces, the reason of this is that is difficult to reach good detail in corners with photon map.

Retrace bounces - when the retrace threshold is used, this difines the number of bounces to be considered, it should be the same as the photon map bounces in orther to match well.

Hope this helps a little more

Gonçalo

[Metin_7]

Perfect! This is one thread I'm going to save for future reference. Thanks Photon King!

Some additional info from my fresh experience:

The amount of cast photons (amount of photon GI detail) can be refined by increasing the Diffuse Subdivisions of any light in your scene. You can open the window from the System rollout in the VRay render dialog.

Cheers,

M7

[Metin_7]

I saved this thread as a HTML file with the filename "Goncalo on Photons".

[GoncaloP]

a better and detailed explanation will come soon

Gonçalo

[Psy]

Thank you GoncaloP! Even what you have said simply has helped a lot, I will try tonight on an interior to get it to work.

Here is a quick question, is it necessary to render out a photon map (1st bounce) and have it set to save as irradiance map once and then re-render with it set as irradiance using that photon map?

[GoncaloP]

no it is not neccessary...

[jedisalf]

a better and detailed explanation will come soon

Gonçalo

where?...and when?

[GoncaloP]

Photon map tutorial from Vlado!

Gonçalo