Brute force Test Very slow :(

[william.morris]

I tested Brute force and LC settings from another thread on a static scene with camera movement only, that I am currently working on.

Below video has been rendered by precalculating the IR and LC. The frame times were roughly 30-60mins deepening on sequence.

But I thought I would test same sequences using brute force and LC method and render times we 4x slower and more noise

Dont know if this is normal, or I am doing something wrong

[iancamarillo]

can u upload the BF version too?

[coolhand78]

nice animation.

are you using vray 3.4/3.5?

post up your settings.

[rikou]

I often have to deal with IR+LC when I have some interior to do... Frequently, I can't have a good ratio between render time/quality when I try to use BF+LC.
However, I would love to definitively avoid IR !

I will try with vray 3.5 ASAP.
Anyway, I am interested in any information about it

[william.morris]

Thank You!

I rendered the whole animation in 3.4, but I have been testing stills in 3.5.

I rendered a region of this still to demonstrate.



With 'Brute force' the region took '30 minutes' and with 'irradiance map' it took 13 minutes. As you can see from example below brute force took twice as long and has clearly a lot more noise.



The Brute force settings I used were as below: all I did when I rendered the irradiance map version, was to swap brute force for irradiance map and set to medium and 60/40.



I wanted to render/animate the doors opening perhaps sun change direction, but as the precalc takes so long with animation pres pass. I wanted to look at the brute force method. But from tests frames times are 2/3/4 times slower and a lot noisier.

I rendered this a couple of years ago with animation pre-pass and brute force and that seemed to work well, but again the precalc took ages to complete.

https://vimeo.com/willmorris/3dhouse

If I am doing something wrong It would be great if someone could let me know? or if this is usual when using brute force and light cache.

Thanks again

Will

[coolhand78]

the only thing i notice is that you have the Noise Threshold set quite high for the image sampler...
i'd reduce that to at least 0.01, i'd also increase the Max Subdivs to say 24 and reduce the bucket the width to 16...

might be worth rendering a sample rate pass as it will give you a bit more information as to whats going on...

[william.morris]

Thank you for your reply.

I tried dropping the clr threshold to 0.01 but render times increased (1h 30mins), so i kept it at 0.02 and I upped the subdivs to 40. changing bucket width has helped.

I know i shouldn't but i switched on subpixel mapping and clampout and that made the render a lot lot quicker.

I got the frame times down to roughly 1 hour at 1920x1080, which is a balance with a little bit of noise. there is a lot of reflection, grass and trees. I am rendering a small 150 frame camera pan with the glass doors opening

I have no idea if that is reasonable? or still excessive? but it seems to be the best balance.

the noise is fine everywhere else except on the white walls and ceiling any ideas why that is?

[Jiri.Matys]

May I ask what HDRI you are using? Or what color workflow (gamma, color settings). Interesting interior has almost same brightness as exterior.

[william.morris]

Hello,

I am using two of Peter Guthries HDRI's 1044(overcast) & 1853(low sun). Settings are fairly default IR+LC. Gamma 2.2. Reinhard 0.1.

The interiors I used the overcast hdri, hence why there may not be a lot of contrast between inside and out. Do you think it looks incorrect?

[Alex_M]

Another guess - is your image properly exposed through the camera and without applying any adjustments in VFB/post? If it's underexposed and you boost the brightness artificially in VFB or post, you're boosting the noise too.

[Morne]

In your BF + LC version you have AO switched on under GI. This increases the render times. BF is already accurate and works out correct contacts and there's no need to add additional AO

[coolhand78]

In your BF + LC version you have AO switched on under GI. This increases the render times. BF is already accurate and works out correct contacts and there's no need to add additional AO

yep def switch that off - i missed that..!

[william.morris]

Thanks for your replies.

Your right my image is a little under exposed which I was going to boost in post, which i not going to help with the noise. Will tweak camera settings.

Oh yes didnt think to turn off AO, your right that is probably is affecting my render times. I will do a few tests.

I rendered these few frames last night with previous settings, its fairly clean with no flickering. I do love the fact there is no fussing with any precalc. BF+LC.....render.

Frame times 1 hour per frame on my Dual Xeon (32 threads) and 3 HOURS on (8 thread) render farm machines

[william.morris]

Just did a quick test and I also just found out dropping the shading rate from 6 to 3 has also made a huge difference to render times. tbh....not to sure why.

[Morne]

What GPU's do you have? Might be worth giving RT GPU a try if you have something modern