Some test

[S0nny]

Hi, today I set up a very simple scene just to test some materials and experiment with Kray.
There are some settings I don't understand well, this is my first attempt because I always used the default lw engine.

Here are the 2 super basic raw renders, no post production, no tone mapping, just the two jpgs saved from the image viewer. Keep in mind that this is not a comparison, just a test to help me understand how the engine works.
So, this are my questions/observations:

- besides the tone mapping (lw render is srgb color space, which I like a lot because is fine with just a little pp), I see a different rendition in materials that I don't undestand: i.e. the wood, the floor and the curtains, I mean not just the colors.
The plexy seems a bit different in reflection also, look at the bottom of the transparent chair. Are the difference because of the tonemap or other settings?

- It seems strange how AA works, what's the best algoritm? I tryied quadratic 0.5, 1.0 and 2.0 Radius to see what's change, but with greater radius i get a really soft image, and with small value I get moirè on wood and fabric without a clean result. Coming from lw which is easy with unified sampling I'm a bit lost with this settings...

- What's the problem with the noise under the transparent chair? Is it because of the AA or the shadow/lights sampling? What's the equivalent of lights/shadow sampling in kray?

- Another big problem: if I save images as png32 for composiiting (just for the background) I lost all the transparent objects. See the third image. How does the alpha for transparency works?

That's it for now, many thanks in advance!

update: added the kray tonemapped, I still see a strange behaviour in wood and the curtains...

[Janusz Biela]

Hi, today I set up a very simple scene just to test some materials and experiment with Kray.
There are some settings I don't understand well, this is my first attempt because I always used the default lw engine.

I will try help but last time I used LW engine native render 9 years ago.

- besides the tone mapping (lw render is srgb color space, which I like a lot because is fine with just a little pp), I see a different rendition in materials that I don't undestand: i.e. the wood, the floor and the curtains, I mean not just the colors.
The plexy seems a bit different in reflection also, look at the bottom of the transparent chair. Are the difference because of the tonemap or other settings?

Tone Map has nothing to do with this. If You want compare tone maps then simply turn in LW to LINEAR and in Kray also LINEAR.
Differences comes from a bit different way rendering of bump map, reflection blur, etc. But it should be big differences. Remember Kray use full bounce light system so having 12 bounce light in Kray is more richer then in LW with 3-6 bounce light (of course you can setup same as in Kray but I am not sure about speed render in LW and transport of light - it can be difference. For Kray is doesn`t matter 10, 20 and more recurce - speed is the same. More recurse brings more light in scene but I think 10-12 is optimal)

- It seems strange how AA works, what's the best algoritm? I tryied quadratic 0.5, 1.0 and 2.0 Radius to see what's change, but with greater radius i get a really soft image, and with small value I get moirè on wood and fabric without a clean result. Coming from lw which is easy with unified sampling I'm a bit lost with this settings...

Best settings: FSAA G3 Quadratic 1.0
To reduce moirè effect you need more passes G4 or G5 but I do not recommend. Better is to use Bum Drop Off. Soon will show how.

- What's the problem with the noise under the transparent chair? Is it because of the AA or the shadow/lights sampling? What's the equivalent of lights/shadow sampling in kray?

It is too small min/max blur - but I doubt. Value 200/500 is enough.Blur noise comes from strong luminescence or from not supported Node. Hard to say from only image without surfaces setting or Kray settings.

- Another big problem: if I save images as png32 for composiiting (just for the background) I lost all the transparent objects. See the third image. How does the alpha for transparency works?

That's it for now, many thanks in advance!

Hmm I have to check it. I do not use png32.

update: added the kray tonemapped, I still see a strange behaviour in wood and the curtains...

This is from differences in transparency/blur/bump levels between Kray and LW. You are used by LW settings.
Blur under transparent chair comes from too strong light from outside.

If I missed something please write or share test scenes.

[S0nny]

Remember Kray use full bounce light system so having 12 bounce light in Kray is more richer then in LW with 3-6 bounce light (of course you can setup same as in Kray but I am not sure about speed render in LW and transport of light - it can be difference. For Kray is doesn`t matter 10, 20 and more recurce - speed is the same. More recurse brings more light in scene but I think 10-12 is optimal)

In lw global illumination settings in this scene is 12 Indirect bounces, and 12 Ray Recursion Limit, but I don't know if this are the settings we are talking about: is there a settings for bounce in kray or kray does read the global gi settings in lw? I can't find it in kray options, maybe under another name?

Best settings: FSAA G3 Quadratic 1.0
To reduce moirè effect you need more passes G4 or G5 but I do not recommend. Better is to use Bum Drop Off. Soon will show how.

Ok, to my eyes FSAA G3 quadratic 1 is too soft, maybe it's me but I like a stronger AA (the new image at the bottom is FSAA G3 quad 1.0)

It is too small min/max blur - but I doubt. Value 200/500 is enough.Blur noise comes from strong luminescence or from not supported Node. Hard to say from only image without surfaces setting or Kray settings.

Ok the node is just a simple dielectric with some super light bump

Hmm I have to check it. I do not use png32.

Ok, because I use png/tga with alpha lot when I need to do small compositing (simple stuff like this, backdrops for windows etc)

This is from differences in transparency/blur/bump levels between Kray and LW. You are used by LW settings.
Blur under transparent chair comes from too strong light from outside.

If I missed something please write or share test scenes.

Thank you Janusz, here are a new image, I changed some settings (like in blind, since I don't know precisely what I am doing with some parameters ). The AA seems to soft for me. Anyway, also an image of all the settings and the wood surface.

[S0nny]

Ok maybe I found the problem with the wood: the reflection map for blur is simply too strong, and since behave very different from lw is better to resurface if coming from lw. The reflected red is a bit punchy btw, it's like coming from a luminious surface...

[Janusz Biela]

In lw global illumination settings in this scene is 12 Indirect bounces, and 12 Ray Recursion Limit, but I don't know if this are the settings we are talking about: is there a settings for bounce in kray or kray does read the global gi settings in lw? I can't find it in kray options, maybe under another name?

simply in cmd line (last misc tab) put:

Code: Select all

recurse 12

It means 12 bounce light.
MAximum limit for Kray is 1000.

Ok, to my eyes FSAA G3 quadratic 1 is too soft, maybe it's me but I like a stronger AA (the new image at the bottom is FSAA G3 quad 1.0)

It is for Hi Res renders. Smaller images need a bit sharper filter (for example Quadratic 0.6)

Ok the node is just a simple dielectric with some super light bump

Dielectric has bug it makes hot pixels in renders (G. told me it is problem on Dielectric side not Kray)

Ok, because I use png/tga with alpha lot when I need to do small compositing (simple stuff like this, backdrops for windows etc)

Actually I do not use this. Try maybe simple planar background with ray tracing flags OFF in LW setup.

In set up tabs:

GENERAL: gamma 1.0 means Linear. Better switch to Linear and use Kray Tone Map Blending

PHOTONS: make Precache Distance 100%

FINAL GATHERING
- make 2 passes
- spatial is too high (it reduce samplings) 0.07 starts good value
- Path Passes must be 1.0 / 75% (It is very important function)

QUALITY
- I suspected weak blur - 200/500 minimum

[S0nny]

Dielectric has bug it makes hot pixels in renders (G. told me it is problem on Dielectric side not Kray)

Ouch, so is it better to avoid dielectric? I use this node a lot because I can set the absorption to get colored glass and also a good looking in the thick side of the objects. Is there a way to manage absorption without using the dielectric node?

Anyway, in this case I sorted out the problem with the noise under the transparent objects: there were no space between the chairs and the floor, so I just moved the objects 1mm on Y to detach them from the floor. Probably transparent material need some 'tolerance' when in contact with other polygons, even if they are in another layer. I can see the splotches on the wall back the chairs (chairs are under direct ies lights), is this the light leaks bug node? It's similar to a very bad caustic calculation.

Actually I do not use this. Try maybe simple planar background with ray tracing flags OFF in LW setup.

I can't do this because often my client wants to replace or change the background in pp...

In set up tabs:

GENERAL: gamma 1.0 means Linear. Better switch to Linear and use Kray Tone Map Blending

PHOTONS: make Precache Distance 100%

FINAL GATHERING
- make 2 passes
- spatial is too high (it reduce samplings) 0.07 starts good value
- Path Passes must be 1.0 / 75% (It is very important function)

QUALITY
- I suspected weak blur - 200/500 minimum

Sorry, where is this blur setting?
Here's the new raw render with a new cfg file and the new settings... It's a bit heavy, almost 1 hour on a i7 6core/12thread @4ghz, Is it right or slow?
I'm slowly starting to understand how to change my materials for kray, I'll probably miss the vpr, but I need to test more. Anyway is a good looking result for a first setup test.

[Janusz Biela]

Instead of Dielectric Try Colour Filter in LW. It can happen with glass that problem when materials are on stick - it is normal. You get Hot Photons behind chair because of Dielectric (Caustic in Kray.cfg is OFF)
The time render should be smaller but You used curtains with refraction blur (I am not sure) This is very slow (It will be faster in K3 with new engine)
VPR is in K3 now.
Try this setting, I think the best for Final Gathering now (it doesn`t mean fast!)

I think you get very well with Kray

[S0nny]

Instead of Dielectric Try Colour Filter in LW. It can happen with glass that problem when materials are on stick - it is normal. You get Hot Photons behind chair because of Dielectric (Caustic in Kray.cfg is OFF)

Ok, so you are suggesting a fresnel glass with color filter applied, I'll give it a try.

The time render should be smaller but You used curtains with refraction blur (I am not sure) This is very slow (It will be faster in K3 with new engine)
VPR is in K3 now.
Try this setting, I think the best for Final Gathering now (it doesn`t mean fast!)

Ok, I'll give it a try in the next days because right now unfortunately I'm a bit busy, I'll keep you updated after the weekend!

I think you get very well with Kray

Wow, thank you so much!