Saving Irradiance Map and Light Cache Question

[short cirkuit]

Hi guys

I have a question regarding saving irradience maps and light caches for final rendering.... so i learn along my journey that you could do a low res render and then save out the irradience map and light cache files and then load them in for a final render. So what i normally do is, set low values such as the below for a low res render just so save these files out:


IM=very low (50/20)
LC = 400
min max sub divs set to 1/24 and
noise threshold set to .01
resolution 1000x600.

Then i render (usually 1-2 mins) save out the IM and LC and then set up the below HIGH settings for final render.
IM= medium (90/30)
LC = 2000
min max sub divs set to 1/60 and
noise threshold set to .015
PS I got the min/max and noise threshold from Grant Warwicks recent sampling tutorial.
Resoltion set to 4000x3000.

Now Im just wondering, is there anything wrong with this technique? I mean saving out the LC and IM on low settings? Should there be a minium setting/resolution that I should adhere to in order to save out a decent enough IM and LC?
The renders tend to come out pretty clear but just triple checking im not missing something or I should be doing something more?

Hoping i make sense.

Thanks and looking forward to your responses

[svetlozar.draganov]

Here are some notes:

IM=very low (50/20)
LC = 400
min max sub divs set to 1/24 and - Image Samples settings are not taken into account during the GI pre-calculation, this step is not necessary.
noise threshold set to .01 - The same thing applies for this step as well.
resolution 1000x600.

Then i render (usually 1-2 mins) save out the IM and LC and then set up the below HIGH settings for final render.
IM= medium (90/30) - Changing IM subdivisions doesn't affect anything when IM is loaded from file. Interpolation Samples however are taken into account.
LC = 2000 - Changing LC subdivisions doesn't affect anything when LC is loaded from file.
min max sub divs set to 1/60 and
noise threshold set to .015
PS I got the min/max and noise threshold from Grant Warwicks recent sampling tutorial. Min/Max Samples and Noise Threshold values are unique for every scene, taking them from any tutorial or good looking scene will not guarantee that those are the best settings for your scene.
Resoltion set to 4000x3000.

Should there be a minium setting/resolution that I should adhere to in order to save out a decent enough IM and LC?
There is no minimum resolution rule, it is up to you to find the most optimized resolution for the scene.
Please note that the LC is not resolution dependent in general, you will notice a difference in the LC only if the scene contains dynamic geometry like Displacement, Subdivisions, Hair&Fur.

[short cirkuit]

Thanks for the info. But what i get confused with the MIN/MAX shading rate is that the tutorials you guys do it on and others online, are based on an unrealistic scene (ie a torus/teapot). For archviz and heavier scenes where were doing renderings at 4k+, how do you test this out?
I mean, for us to tweak and test with the MIN/MAX shading rate to get it just right will still take quiet a bit of time as how would you test it with such high settings and high resolutions?
I believe we were told there was going to be an indepth tutorial on it, hoping this is still in the pipeline?

Here are some notes:

IM=very low (50/20)
LC = 400
min max sub divs set to 1/24 and - Image Samples settings are not taken into account during the GI pre-calculation, this step is not necessary.
noise threshold set to .01 - The same thing applies for this step as well.
resolution 1000x600.

Then i render (usually 1-2 mins) save out the IM and LC and then set up the below HIGH settings for final render.
IM= medium (90/30) - Changing IM subdivisions doesn't affect anything when IM is loaded from file. Interpolation Samples however are taken into account.
LC = 2000 - Changing LC subdivisions doesn't affect anything when LC is loaded from file.
min max sub divs set to 1/60 and
noise threshold set to .015
PS I got the min/max and noise threshold from Grant Warwicks recent sampling tutorial. Min/Max Samples and Noise Threshold values are unique for every scene, taking them from any tutorial or good looking scene will not guarantee that those are the best settings for your scene.
Resoltion set to 4000x3000.

Should there be a minium setting/resolution that I should adhere to in order to save out a decent enough IM and LC?
There is no minimum resolution rule, it is up to you to find the most optimized resolution for the scene.
Please note that the LC is not resolution dependent in general, you will notice a difference in the LC only if the scene contains dynamic geometry like Displacement, Subdivisions, Hair&Fur.

[Zdravko.Keremidchiev]

Unfortunately there is no fast way to determine the right min/max values for the particular scene, especially on a huge resolution. I would suggest using render regions on the more problematic spots and check the render elements sampler info, lighting, reflection, refraction, GI etc. to get reference for a good sampling correction.