Re-using a saved IR map ?

[Hussam_CG]

Hi there renderers !
I'm kinda bigginner using Vray ,so...the questions about it are growing in my mind everyday !
here I want to ask you about re-using a previous saved irradiance map ...I know it's a great way to reduce the render time,
but what I want to know is :
what is the settings or scene
render parameters that we shoud NOT change when Re-using a saved IR map ?!
and what is the settings or scene
render parameters that we CAN change cos it's not related in IR map calculations ?!
here's some points that I'm wonbvdering about :
-changing the size of the output image ?
-changing the lights parameters in the scene ?
-changing the materials settings?
-changing the color mapping settings-type ?
-changing the Image sampler (AA) type parameters ?

and please I also want to know about all the other settings that we can or can't change,
waiting for replies,
greetings !
Hussam

[travistlo]

-changing the size of the output image ?

The saved imaps are sizes specific. You can change the size as long as it stay propotional. Of course if you make the image 2 times larger than the saved imap, the new image gi will be less detailed.

-changing the lights parameters in the scene ?

This is sort of an optional time to rerender the imap. If you are still testing your scence, and the light changes will have a minimal impact on the gi solution, then you do not need to rerender the gi, atleast not until final render, or until the light changes are significant.

-changing the materials settings?

This is sort of the same thing as the lights. As long as the material change dont impact the gi too much (like change the color from green to red) then you dont have to worry about it till final render.

-changing the color mapping settings-type?
-changing the Image sampler (AA) type parameters ?

I believe the color mapping and the aa is a post effect. you can change this all you want, you do not have to re-calc the gi

[travistlo]

You can change alot without recalculation. As long as you do not move objects, or add new things, a lot of rendering parameters can b changed.

Obviously if you try to change any of the imap settings, and are using a saved map, then the changes wont happen, then you will have to recalc the solution.

[Hussam_CG]

thank you travistlo !
that was so helpful
I'll ask again when I got questions later on