Rendertimes topic

[J_Bug]

Why?

Because it's called Glossy not Blurry So full Glossy would be 100% (or 1) and no Glossy (or Blurry) would be 0% (or 0).

--Jon

[Sebastiaan]

Sebastiaan:

That should have been directed at TOBTHREEDEE.

--Jon

I misunderstood.....sorry

Seb.

[J_Bug]

no, it's my bad

--Jon

[TOBTHREEDEE]

????????

yeh, let´s try to help Sebastiaan.

[Da_elf]

correct me if im wrong. but arnt glossy reflections blurry reflections. thus glossy = 0 and non glossy =1?

[Sebastiaan]

Also, the GI presets are designed to be used for image sizes around 640x480. So the low setting is actually a very high setting for an image the size you a rendering.

Well...we're rendering images at 4500 pixels with preset LOW..
So as I understand that's very high for such a resolution?!

So what should you use at such resolutions? I've been reading some things about it on vray.info site, but I don't fully understand.
And I understand that it's better to calculate the irradiance map at a smaller resolution and use it for the bigger resolution one?

Could someone please explain it step by step in simple english
I'm pretty confused now.

Thanks,
Sebastiaan.

[J_Bug]

TOBTHREEDEE:
I was just trying to be informative. It seemed that you were confused to why the Glossy values went one way instead of the other.

Elf: Please go look up the word Glossy :P Glossy is the opposite of Blurry in our case

Well...we're rendering images at 4500 pixels with preset LOW..
So as I understand that's very high for such a resolution?!

No, Low would be even lower on a higher resolution such as 4500 px

So what should you use at such resolutions? I've been reading some things about it on vray.info site, but I don't fully understand.
And I understand that it's better to calculate the irradiance map at a smaller resolution and use it for the bigger resolution one?

Yes, this is better in terms of lowering render times.

Could someone please explain it step by step in simple english
I'm pretty confused now.

Thanks,
Sebastiaan.

Assuming you're rendering a still image with the newest build of VRay Advanced...

1)First you find that golden set of parameters that make the GI look good. Set the Advanced irradiance map parameters to Single frame and "On render end" "Don't delete", "Auto save...", "Switch to Saved map" should all be turned on. Understand this because subsiquent renders will use this saved map until you turn off "From file"

2)Next you should go to the Global switches and check on "Don't render final image (only compute GI maps)"

3)Render your image at half or quarter the resolution keeping the same aspect ratio.

4)Now just set the proper resolution and render again but this time with turn off step 2.

Sorry for any confusion.

--Jon

[Sebastiaan]

No, Low would be even lower on a higher resolution such as 4500 px

Ok..so what DanielBrew is saying is wrong ("Also, the GI presets are designed to be used for image sizes around 640x480. So the low setting is actually a very high setting for an image the size you a rendering.")
That is what confused me....cause it seems more reasonable that on a higher resolution you need higher settings.

Assuming you're rendering a still image with the newest build of VRay Advanced...

1)First you find that golden set of parameters that make the GI look good. Set the Advanced irradiance map parameters to Single frame and "On render end" "Don't delete", "Auto save...", "Switch to Saved map" should all be turned on. Understand this because subsiquent renders will use this saved map until you turn off "From file"

2)Next you should go to the Global switches and check on "Don't render final image (only compute GI maps)"

3)Render your image at half or quarter the resolution keeping the same aspect ratio.

4)Now just set the proper resolution and render again but this time with turn off step 2.

Yes...I just did precisely that at my work before I went home. So I'm curious if the render is finished tomorrow morning

DanielBrew...I tried using your settings for interpolating...but with your settings in my test scene it rendered longer than without interpolation..
So I tweaked a bit with the interpolation settings but I couldn't get it to render faster...maybe just a few seconds faster. I tested it on a low resolution though...dunno if that matters. Or maybe I'm doing something wrong.. But it didn't work

Thanks again all for your help so far!! I'm getting there

Sebastiaan.

[J_Bug]

I didn't say DanielBrew was wrong. I think you may have just understood it wrong.

--Jon

[flipside]

1. I'm also using the word glossy in the sense of blurry, I thought it was the same! Never looked up that word in a dictionnary...


2. Your going the wrong way with your GI settings man!!! A higher resolution needs LOWER min max settings! (for example: -3 is lower than -2, to avoid any confusion here...)

The min max settings do exactly what this whole saving and reusing on bigger resolution does. The min/max settings are resolution dependant. You only need to save your IR map for animations or for quick tests of materials etc so you don't need to recalculate the IR map again. Note that every change you make to any object or material has an effect on the IR map, so reusing a map on a scene where you changed something can give strange results.

min/max= -3/-1 on an image of 800*600 for example means that the irradiance map is calculated in 3 passes:
pass1: GI info is calculated at a resolution of [800/2/2/2]*[600/2/2/2]=100*75
pass2: GI info is calculated at a resolution of [800/2/2]*[600/2/2]=200*150
But in this pass, vray already has some GI info gathered from the first pass, so it knows now where more or less detail in the scene is. Vray uses this info of the first pass to further calculate the GI on the 100*75 resolution image. More 'samples' are used in areas where more detail is needed, no more samples are added in undetailed areas like celings or walls.
pass3: GI info is calculated at a resolution of [800/2]*[600/2]=400*300
Again the info of previous passes is used to place more samples in appropriate places.

So what you did actually is using the GI info of pass 3, which is the GI info for the 400*300 image, on an 800*600 image.

If you now would want to render a 1600*1200 render with same IR map calculation time, you need to use LOWER min max settings, otherwise IR map calculation will take lot longer!
-4/-2 on 1600*1200 gives you this:
pass1: GI info is calculated at a resolution of [1600/2/2/2/2]*[1200/2/2/2/2]=100*75
pass2: GI info is calculated at a resolution of [1600/2/2/2]*[1200/2/2/2]=200*150
pass3: GI info is calculated at a resolution of [1600/2/2]*[1200/2/2]=400*300

As you see, you have again your GI info of a 400*300 image.

If you would first render an 800*600 image on -3/-1, then save this map and reuse it on a 1600*1200 image, this would be exactly the same as just rendering the 1600*1200 image in -4/-2

You can see for yourself what the effect would be if ou would use higher IR settings on higher resolutions (-2,0 on that 1600*1200 image would calculate pass1:400*300; pass2:800*600 and pass3 1600*1200!!! The GI would be very detailed)
If you would use same IR settings for 800*600 res for a 1600*1200 image, your GI details will look better but your IR calculation time will be lot slower!

All this is on vray.info too:
http://www.vray.info/entry.asp?entryID=101

Hope you understand my explanation



Then, to improve on render speed, glossy materials slow down rendering a lot. Use low subdivs for the glossy effect to speed up rendering. using interpolation speeds it up too but usually looks worse.

Another very important factor is area shadows. Also use low subdivs here. In other words, everything that is blurry will slow down rendering, wether it is materials or shadows or whatever.

flipside

[Sebastiaan]

There was a lot of confusion, but it's getting all clear to me now. I'll be doing some more testing today!
Thanks flipside!! And to everybody by the way!!!!

Sebastiaan.

[Gijs]

Hi Sebastiaan

Have you played with QMC settings yet? Try increasing the noise from 0.005 (default) to something like 0.1 Then if the noise level is too high, decrease it by 50% until you have found the best quality/speed ratio.


Gijs

[Sebastiaan]

Hi Sebastiaan

Have you played with QMC settings yet? Try increasing the noise from 0.005 (default) to something like 0.1 Then if the noise level is too high, decrease it by 50% until you have found the best quality/speed ratio.


Gijs

No...never used that option before. But it's hard testing scenes at big resolutions...
If you test that option on a low resolution, do you get a good example of what it will look like on high resolution?

Thanks!!!


btw. I've put all my renders in the queue with the new settings for the irradiance map...So I'm very curious if the renders are finished tomorrow morning... I'll let you guys know

Sebastiaan.

[DanielBrew]

Hi Sebastiaan,

Sorry my settings for interpolated glossies didn't speed things up .

The Min Max values for interpolated reflections work in the same way as those for the irradiance map. So to speed things up you simply use lower values, for example Min -6 Max -4. If your rendered image becomes noisy increase the 'Interpolation Samples' from the defalt 20. I'm not exactly sure what values will work for you as I don't render images as large as yours.

You could find out how much of your render time is due to glossies by re-saving your scene and setting the glossiness to 1 for ALL materials. Then re-render. If it is still slow then, as Flipside said, it is probably down to lighting.

Best of luck,

Dan

[Sebastiaan]

Sorry my settings for interpolated glossies didn't speed things up .

Well thanks a lot any way for the effort!!

The Min Max values for interpolated reflections work in the same way as those for the irradiance map. So to speed things up you simply use lower values, for example Min -6 Max -4. If your rendered image becomes noisy increase the 'Interpolation Samples' from the defalt 20. I'm not exactly sure what values will work for you as I don't render images as large as yours.

I used those exact values for my high-rez render..so I'm pretty curious how long it will render!

You could find out how much of your render time is due to glossies by re-saving your scene and setting the glossiness to 1 for ALL materials. Then re-render. If it is still slow then, as Flipside said, it is probably down to lighting.

ok, I'll look into that!

Thanks!
Sebastiaan.