Kray QLWF vs. LW sRGB

[medzo]

Hi, everybody!

I have encountered on a small problem. I was doing some studio interior tests. For lights I used lightwave's area lights for better shadow contact because lumi polygons just dont give nice contact shadows. I had to use Trace Direct Light Reflections option because if not there are no specular highlights. But there i ran into this problem. Reflection blurring with standard Kray's QLWF produced just too much noise even when settings were very high. Than just for ''fun'' I have disabled Kray's QLWF plugin and activated Lightwave's sRGB colorspace. There were some minor color differences between renders but the reflection blurring was perfect..like it should be. I also experimented with Dpont's lights, which produced just too much highlights.

I am attaching two renders so you can see for yourself.

The method with sRGB is more time consumig (which I dont understand why) and another thing... kray's QLWF makes renders much more saturated, does anyone know why?

[Janusz Biela]

I have encountered on a small problem. I was doing some studio interior tests. For lights I used lightwave's area lights for better shadow contact because lumi polygons just dont give nice contact shadows. I had to use Trace Direct Light Reflections option because if not there are no specular highlights.

Remember Area Lights are raytracing physical lights so there is no interpolation..why they render slow with ideal shadows. Lumi poly has same behavior but to see good shadows You need very strong setup or UNCACHE render (which means no interpolation). Generally are no big difference between Area and Lumi if You will use no interpolation render, called UNCACHE.
I suggest not to use specular because is complicate, hard to control and make artificial effects (personally I do not use specular).
Better NOT to use TRACE DIRECT LIGHT REFLECTION from Kray...make noise in reflection.
...so the best solution (and only one imho) are Lumi Panels turned to raytracing without shadows under LW setup object. Light You will create from Area lights.

But there i ran into this problem. Reflection blurring with standard Kray's QLWF produced just too much noise even when settings were very high. Than just for ''fun'' I have disabled Kray's QLWF plugin and activated Lightwave's sRGB colorspace. There were some minor color differences between renders but the reflection blurring was perfect..like it should be. I also experimented with Dpont's lights, which produced just too much highlights.

Perhaps noise was from TRACE DIRECT LIGHT REFLECTION. With Lumi blur is very fast and without noise.
About LW Gamma...You have no choice . This is only one way to render correct. But I suggest to add small percent of Exponential (for reducing bloom effects near light) but not strong because Exponential make false colors and too much "bend" light behavior .

The method with sRGB is more time consumig (which I dont understand why) and another thing... kray's QLWF makes renders much more saturated, does anyone know why?

different tone mappings make different time of render (but is not big deal) some tone mappings need a bit more calculations (there is also implicated AA phase - WHY when we setup pure Exponential and Catmull pixel filter - render is not that sharp as should be because Exponential is very strong tone mapping). About LWF make too much saturated renders: there is problem with textures, perhaps they are too saturated originally or scene has bad light. I use almost pure LWF and everything is ok (Of course almost all textures need a bit tweak because they are too bright, too dark, too saturated etc)

[medzo]

tnx for clarification. so if i use strong setup what would that be? 3 FG passes + spatial tolerance under 0.05 + maybe path tracing passes? i am trying this settings, i can see nice contact shadows but render times are realy high... what would you recommend?

One more thing. If you dont use specular and glossines input - how do you produce specular highlights?

[jure]

Hi, everybody!

I have encountered on a small problem. I was doing some studio interior tests. For lights I used lightwave's area lights for better shadow contact because lumi polygons just dont give nice contact shadows. I had to use Trace Direct Light Reflections option because if not there are no specular highlights. But there i ran into this problem. Reflection blurring with standard Kray's QLWF produced just too much noise even when settings were very high. Than just for ''fun'' I have disabled Kray's QLWF plugin and activated Lightwave's sRGB colorspace. There were some minor color differences between renders but the reflection blurring was perfect..like it should be. I also experimented with Dpont's lights, which produced just too much highlights.

I am attaching two renders so you can see for yourself.

01- krays QLWF.png

02-lightwaves sRGB colorspace.png

The method with sRGB is more time consumig (which I dont understand why) and another thing... kray's QLWF makes renders much more saturated, does anyone know why?

I cannot replicate your findings but it must be because when you use LW tonemapping Kray is sampling blur in linear space which will identify contrast between blur samples more easily. You can try if you get the same effect with using importancegammamultiplier 0.5 command.

On the other hand I never found trace direct lights too useful. I use specularity and glossiness to get the same effect much faster.

[Janusz Biela]

tnx for clarification. so if i use strong setup what would that be? 3 FG passes + spatial tolerance under 0.05 + maybe path tracing passes? i am trying this settings, i can see nice contact shadows but render times are realy high... what would you recommend?

If You have light everywhere is hard to see shadows Also You need setup correct Kray for that. try this one:
http://www.kraytracing.com/joomla/forum ... &mode=view

One more thing. If you dont use specular and glossines input - how do you produce specular highlights?

I do not I just render with real behavior of reflection+blurr. Specular is old fake engine for simulate reflection with blur and it was create in time when computers was very slow (and still they are)...so in real world specular does`t exist
Kray is enough fast to forget about this and use real reflection/specular combination which in my opinion is much better then specular but need training - need observation how looks real material around You.

[medzo]

Thanks for the input guys! I appreciate it, but I am still strugling...

So I am attaching the scene. It is set to sRGB, krays QLWF is disabled, Lw's Area lights are on, Trace direct light reflections is also on... so if you open the scene and just press render, you get the effect that is, for me, ok.

Now to the problem(s).

1. After reading previous comments, I don't think it is a good idea to use lw's sRGB, it wold be better to just use kray's QLWF
2. If I swithch to kray's QLWF I get noise in reflections because of Trace direct light reflections, so I disable it and get a flat surface with no highlights.
3. Even if i disable lw's area lights and replace it with lumi polygons the noise is still there and highlights are looking very bad.

So how can I use kray's QLWF + area lights (or even lumi polygons) with no trace direct light reflections on to get nice highlights on plastic chair.

I am attaching the scene, so you can check materials, lights and scene setup... i am probably doing something wrong...

[Janusz Biela]

Here Your scene with setup (You can use it for interiors also)
In scene You have a couple of boxes (for testing contact shadow) and also plastic chair with high blur. Setup for blur is huge but remember high luminosity value need high setup of blur ...why I use Area lights + blur with small luminosity value.
In scene You have Area lights which are switched to Lumi poly in Kray menu.
Tone mapping : LWF Gamma with small amount of Exponential.

[medzo]

janusz could you share the scene, please?

[Janusz Biela]

janusz could you share the scene, please?

Ahhh freak...I forgot attach zip ...sorry!

[medzo]

Thanks Janusz , you are the man!!!