www.kraytracing.com

Hi,

My latest exterior work. This time I tried PathTracing with recurse 5. Render times between 1-2h on i7 4770 with 16Gb memory. I should upgrade to 32Gb soon, this scene contains 6.9 million polys + instances and it consumes 14Gb ram while rendering in 1500x1000 resolution. With this amount os polygons loaded, it's very-very slow to switch between Layout and modeler. Does anyone know any tricks to prevent this?

more images...

Very good job! Finally somebody starts use PT!

Here my tips:
- 5 recurse , very good! (over too slow, lower too dangerous for glass - this last will be fixed in K3 by special shader) . But is problem with recurse 5...too less bounce light. This make render similar to LW native render...very bad effect. But it is solution for that - not perfect but better then nothing - is enough to raise up Global Power in Kray menu. So for that I think the best is Power 1.5. It will simulate recurse 5x1.5=7.5 and this will be enough.

- lower Sun with desaturate command - will give warm and soft light.

- I think the best FG for Path Tracing is 100/500 - this is minimum (of course FG has different meaning when you switch to PT in Kray - it is not Final Gathering) . For Hi Res images this value is very good and can be even smaller (FG 100/300).

- I am not sure what you add on the leafs. If this is QMC shader then very bad. QMC needs photons map to be calculate. Better is set up ZERO photons in Kray (Path Tracing doesn`t need photons!) ...and that`s it. So no shaders for leafs, grass. The big positive thing is that: render starts immediately, no errors, no problems, no splotches, no light leaks. You can increase speed of render for plants by smaller value of Path Tracing - for example for grass FG 50/100)

- RULES NUMBER ONE for PT: no extra sources of light in exteriors! If you have ONLY Physky + Sun then speed of render is crazy. But do not try add extra lights, lamps, lumi, physical lights, etc! The amount of calculation for samples will start rapidly growing, also noise. This is explanation, why Octane, Maxwell render fast and we think they are fast. There is nothing magic in these software. One source of light - fast render. Two sources of light - slow render. Three - forget about it. But real problems starts with extra light or interiors scenes - then starts be really slow - is just too big amount of data to calculate.
In exteriors many photons after one bounce just "die" - and this increase time speed render.

- noise from render can be reduce by Denoiser II in AE (very good software)

I would like to see original render to check how Denoiser will reduce noise from renders.

Hi,

Janusz, thanks for your comments and advices!
My setup is not Phsky+Phsun, so as I read your advices, I was very happy to hear about rendertime boosting otions
I made some test:


01 - 8:08 (488sec)

I removed all the vegetation, the original setup is the same:
- PathTracing fg 100/1600
- Global Photon Power: 1.5 (Yes, like Janusz said - I also realized this)
- Photons: 0 - ONLY PathTracing, surface shaders also use only PT
- Light setup: GI dome (200% lumi sphere 7000K, unseen by cam, no shadows) + Sun (LW Area, 1km distance, 100%, 6500K), NO other light or lumi poly


- tone mapping: Gamma 1.0/1.0 (I want high contrast. maybe I could rise it to 1.2 or 1.4, but it's OK for me) - this results the native LW render look , Limit DR Before Tonemap
- walls surface shader: force PathTracing with fg 1000/2000 (to remove the noise from the most visible surface)
- leaves (removed from this test, but: surface shader: force PathTracing with fg 0/0) - I know it results noise, but the deadlines....
- AA high (for this test I changed the grid size from 3 to 2 - The original images were made with grid 3)



02 - 3:45 (225sec) - this will be the new base image

To speed up test renders, I modified some parameters:
- global fg down to 100/500
- surface shaders removed fro walls

Now the speed is ok, but the noise is not - but now I dont't care about noise, I want to test as fast as I can.



03 - 2:28 (148sec)

- GI dome (200% lumi dome 7000K, unseen by cam, no shadows) turned off
- Sky (ball with spherical image, unseen by Rad., no shadows) turned off
- Tree images (images on planes, unseen by Rad., no shadows)
- Sun (LW Area, 1km 100%, 6500K) turned off

The only lightsource was the white LW background - The boosted renderspeed is obvious




04 - 3:26 (206sec)

- Phsky with sun turned on (sun position almost matches the original)

Conclusion in terms of rendertimes: If I use Phsky + Phsun instead GI dome + LW Area I gain 10% on render times, but the noise level is the same

05 - 3:25 (205sec)

- Phsky sun turned off & original LW Area turned on (I want to controll the position of the sun on each frame!!!

Conclusion in terms of rendertimes: Phsky Sun = LW Area (image 04 & 05)



06 - 3:50 (230sec)

- I need realistic reflections, so I turn on Sky & Tree planes

Conclusion: hmmmm turning on theese planes resulted 10% increase in rendertimes.... same as switching from GIdome+LWarea to Phsky+Phsun. Let's chek this:




07 - 3:51 (231sec)

- Phsky turned off
- GI dome turned on


My overall conclusions at this point:
- Phsky+Phsun is equal with Gidome+LWarea setup, no difference in rendertimes
- Also no difference in noise - the only way is to rise up global fg max and use the shader with high fg max values on very noisy surfaces (in this test: white walls)
- FOR ME: using my original setup gives me more flexibility - Using



But Let's try one more thing: GI resolution!

08 - 3:52 (23sec)

- GI resolution 600mm instead of 300mm
- OK, I'm a LAME... Sorry, but this parameter does not affect PathTracing renders


Currently I have no more time to play with this scene, but I see, that PT setup is far the best I1ve ever tested.
BUT more testing is needed becouse of the noise:
- my global fg 100/1600 is not ok
- leaves with fg 0/0 is also not ok. I should find a good fg max value for leaves & noisy walls

And here are some original renders.

- House: 1500x1000 - http://total3d.hu/transfer/kray_01.hdr
- Lake: 3000x2000 - http://total3d.hu/transfer/kray_02.hdr

Exactly the same setup&parameters

Thx!

I suggest use only Physky + Sun from Kray. It is very important to receive realistic color and good GI.

Also materials for plants need a lot improve - in progress my Nodes for grass and leafs. Is very important to make them more random but not with shape, with color.

I sugest use just Gamma tone mapping - You can test my setup from here

My test:

Thanks for your answer, Janusz!

I'll test your scene as soon as I'll have some free time.
I like your image, but this client likes the oversaturated look. Might not the most realistic, but his word is the final word

I'm waiting for the grass & leaf materials.

Is there any way to position manually the Phsun? And animate it? Maybe in K3?

Only in K3 will be all those functions (animate, connection with spot light for positioning)

small update:

New higher resolution render, less noise, more PS

here my poste ofcourse only photoshop cs4. thnx for raw render man .

Now is really good. This Instance system from LW is the best system from all!
Grass looks better and water also, I think you used DPkit Node or Rmann - there is really nice Node for water and can be easy connect with subpatch displacement.

Btw
I noticed: when FG for Path Tracing is 1000/0 - is better quality (less noise) than FG 0/1000, time render is the same. Second parameter is not important and can be zero.