PDA

View Full Version : Info about GI

Pavlov
06-03-2013, 01:40 PM
Hi all,
if i render 1500x750 test pictures and GI is ok with pixel settings 2 min and 100 max... to keep exactly same result, which setting should i use if i step to 6000x3000 ?
Since resolution scales of x4, i set 8 and 400, is this conceptually ok ?
I never really understood what min and max pixel mean. Is this a square-side measure ? i.e. 4 means a square o 4x4 pixels, so 16 pixels, or 4 means a 2x2 pixel square ?

thanks
paolo

Nicolas Jordan
06-03-2013, 01:46 PM
If you want to maintain the same GI quality at a higher resolution just set the "Multiplier" setting to %400 instead of %100 and you should get the result you are looking for.

Pavlov
06-03-2013, 01:49 PM
hmmm i think it's the opposite: if i keep same settings and set 400%, GI will be calculated on a 24000 x 12000 pixel pic with mps 2/100, resulting in infinite time. Maybe you want to say 25% instead ?

Paolo

Nicolas Jordan
06-03-2013, 02:06 PM
hmmm i think it's the opposite: if i keep same settings and set 400%, GI will be calculated on a 24000 x 12000 pixel pic with mps 2/100, resulting in infinite time. Maybe you want to say 25% instead ?

Paolo

Your right it's the opposite of what I was saying. %25 is the way to go.

MSherak
06-03-2013, 03:29 PM
Hi all,
if i render 1500x750 test pictures and GI is ok with pixel settings 2 min and 100 max... to keep exactly same result, which setting should i use if i step to 6000x3000 ?
Since resolution scales of x4, i set 8 and 400, is this conceptually ok ?
I never really understood what min and max pixel mean. Is this a square-side measure ? i.e. 4 means a square o 4x4 pixels, so 16 pixels, or 4 means a 2x2 pixel square ?

thanks
paolo

The multiplier is where you would want to go if you up the rez 400% and use the GI at 100% .

1500x750 = 100% image rez : Multiplier = 100%
6000x3000 = 400% image rez : Mulitplier = 25%

On your large image when you render the 6000x3000 it will do 1500x750 for the GI and upscale. Saves time that way. If you do 100% at the 6000x3000 then the GI is at that rez which you know would take a long time and if cached i would be huge.

The problem with Min and Max is that they say pixel which everyone relates to the image or screen. It should be called Min/Max Sample Spacing since pixels is really not the right term. Your Rays shoot off of these samples (RPE) into the world and how many bounces is what happens if/and when it hits another sample. When it does it shoots off rays (SBR) again until it does not hit a sample or hits the number assigned in secondary bounce rays. Once one starts playing with this and visually seeing it, one will know why settings like the GI per object are awesome and helpful for fine tuning your GI for speed. This is all in interpolated mode. Non-Interp is brute force and these options go away.

I have placed up some content with a couple scenes that you can quickly play with.. So thinking 3D spacing not 2D pixels for min/max and it makes things easier. Fun things to try, Set the GI really low and play with the GI at the object level. Turn on Use Gradients and you will see why you get sploches with it.. ;)

-M

Nicolas Jordan
06-03-2013, 03:48 PM
I set my min pixel spacing on some projects to .1 so that the GI detail is calculated even more accurately within each pixel. I usually leave the max pixel spacing at 100.

MSherak
06-03-2013, 05:15 PM
I have been sitting lately on 2 bounce, 24 RPE, 12 SBR with Min .001 Max 10-20. Nice thing is the more bounces the smaller the RPE and SBR. Speeds things up.

Nicolas Jordan
06-03-2013, 05:51 PM
I have been sitting lately on 2 bounce, 24 RPE, 12 SBR with Min .001 Max 10-20. Nice thing is the more bounces the smaller the RPE and SBR. Speeds things up.

I never thought of trying that yet. I will have to try those setting on some of my projects to see what kind of results I get.

probiner
06-04-2013, 05:05 AM
I have been sitting lately on 2 bounce, 24 RPE, 12 SBR with Min .001 Max 10-20. Nice thing is the more bounces the smaller the RPE and SBR. Speeds things up.

I thought Min under 1 did nothing... and just get internally clamped to 1

Cheers

MSherak
06-04-2013, 05:36 AM
I thought Min under 1 did nothing... and just get internally clamped to 1

Cheers

Since it's not an integer input it is taken into account since it really sample spacing. The word pixel is so confusing there on min and max which would be integer for a pixel input. Thought I do know that anything under 10 on the angle tolerance is clamped back to 10 which might be set like that for calculating speed. If you want it under 10 just set to brute force. (interp off)