What is GI in MentalRay after all???

[creativeway]

When does Global illumination turns into action?

 

I'm setting up the ligh in an exterior scene, with MentalRay as render.

I have a mr Area Spot and a Sky dome to light up the scene.

But if I turn on GI it makes no diference in the render!!

 

Why?

 

ty

[Thiago de Andrade]

Is Final Gather turned on? Try turning it off and then you'll notice the photons in action. It helps if you add some ground so the photons can bounce. Also set the radius of photons so you can choose the right amount of them and the level of details. Final Gather must then be turned on to touch it up and unify and correct the whole scene.

[AJLynn]

What shaders sre you using for materials, and how is your light set up?

[creativeway]

I'm using normal shaders for intance. The "blin" shader.

[AJLynn]

It looks like there's some bounced light in your no GI render that wouldn't be there with no GI at all. Are you using Final Gather? That's not explicitly labelled GI but it is a form of GI lighting that can handle the lighting from a sky. Depending on your lighting, levels of the spot light vs the sky light and photon settings, the sun might be making so small a contribution compared to the sky that using the GI photons for the extra bounces from the sun light has a negligible effect. I think that's what happened here - notice that there is almost no sun shadow, which would be there if you had a realistically strong sun.

 

It's also not a great scene for photon GI, being a large scale exterior space with a lot of surfaces where you'll need a lot of photons to get a good result, but I think that if you put a floor in, cranked the sun up, killed the sky and turned off FG (this is just for demonstration purposes) and zoomed in on areas that need bounced light, and tried it with and without GI, you'd see the effect.

[Thiago de Andrade]

Exactly Andrew,

 

I agree, the GI is on but seems to show no or little effect. Keep us posted Ty, with the ground on and the FG off.

[creativeway]

Here is the scene with no Final Gather and Global Illumination ON

 

Scene is too big to join as ZIP file so I made a print screen of the render and material settings.

 

Ty all