"visible to GI" what is this 4?

[skogzort]

Can anyone tell me what the check box "visible to GI" under Vray Object Properties does, and how it relates to "recieve GI" and "generate GI"? I can't find this info in the documentation.

Thanks much for the help

[RErender]

It sets whether or not the object is included in the GI solution. For instance if it were uncheked on a sky dome it would not block the skylight.

[Morbid Angel]

eric is right, visible to gi is like include/exclude option in 3ds max lights.
If object is not visible to gi if will not recieve or cast gi, thus gi rays will pass throught it. Generate gi on its own can force object to send out gi rays based on the intesity of its material. Recieve gi will force object to recieve gi rays thus making it illuminated by gi, but will disable bounce of gi from this object.

[dlparisi]

So is unchecking"visible to GI" the same as unchecking both "receive GI" and "Generate GI"? It seems like it should do more than just that.

[Morbid Angel]

i think visible to gi is like override materials in globals switches. controls globally and the other two are local control.

[R2J2]

(funny I was just about to ask the same question)

-I've just noticed today that unchecking Visible to GI doesn't seem to work untill I uncheck receive & generate GI.
So unless this is just my scene, what is the deal/diferance with it?

Max 7 & VRay 1.47.03

[Da_elf]

an object can recieve GI and generate it yet not block GI from hitting another object

[Da_elf]

in the tutorial i wrote in the tutorial setion of www.elfpro3d.com i discuss the use of that switch in my dont cry over spilt ink tutorial

[skogzort]

Thank you for the explanations. They make sense. The only thing that is still a little confusing to me is the application of the check boxes – I have 2 questions:

Does “visible to GI” act as nothing more then an “on/off” switch for “receive GI” and “generate GI” – so that if both receive and generate are left un-checked and visible is checked, then the object still won’t participate in GI?

or

Does “visible to GI” act as an “override” switch for “receive GI” and “generate GI” – so that if both receive and generate are left un-checked and visible is checked, then that object still will participate in GI?

thanks again for the help

[RErender]

Even with both generate and recieve unchecked the object will block GI rays until visible to GI is unchecked.

[Da_elf]

a good example of GI is skylight (environment light) its pure GI so basically if you had a teapot with with a plane under it and a quad patch grid over it these will be your results if you play with the settings on the grid.

A: RGI on, GGI on VGI on ::: looks normal :::
B: RGI off GGI on VGI on ::: grid will be dark since its not recieving any light :::
C: RGI on GGI off VGI on :::grid will be lit however since light under the grid might be needed to bounce off it to help with lighting, under grid might be a bit darker than A:
D: RGI on GGI on VGI on ::grid is lit. however grid doesnt block GI so teapot looks like its lit as though grid isn't there. since the ground is now brighter. more GI should be hitting the under side of grid.
E: all off ::::looks like a mess ::: hehehe

[R2J2]

Yeah, thanks. should have read your tut Da_Elf

[dlparisi]

It seems like the "Visible to GI" checkbox should be renamed "Cast GI Shadows" or something like that. Although it also appears to turn off "Generate GI" in my tests. I just can't get an unchecked "Visible to GI" object to contribute to the GI, but I can get it to receive it.