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correct Workflow: IBL + mia physical sky!!!


thorsten hartmann
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hi

 

it give some reasons to use IBL. the normal mr_sun is a direct area light + sun shader. This is not 100% correct because...

 

- at the FG-Prepass Rendering is the mr_sun shadow sharp, and not smooth, this do the FG calculating not 100% correct.

- you need to many FG Rays from the environment (mr_sky) to have the same quality as the IBL environment.

- shadow in the evening have sometime colorbleeding overbrights on the smooth shadow edge. This can simulate IBL much better as a Direct aera light + sun shader.

 

mfg

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it was really helpful .. I am wondering if you could show us a correct workflow for MR + Vue in 3ds max ? I saw some cool images you've rendered....and the results looked amazing..somehow I have not been able to achieve like yours..

 

thx in advance

 

Meher

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Hi MrCad,

 

thanks for the nice comment. About VUE, i have at this time only a old Version 7.2 and this is not state of the art. *smile* I have test for some week the 9.5 Version by my client, and that had looks very good. A cool VUE Tutorial is here: http://www.imakeu.com/Tutorials/Vue/

Edited by thorsten hartmann
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Very interesting stuff indeed. The shadows looks much different. softer, but more defined where in areas of little or none ambient light. What about render times??

Does this IBL setup have any impact on interior renders??

 

Btw. the ground looks much brighter in the IBL renders. why is that? is the ambient light distrubeted better compared to the standard Sun & sky??

Edited by Braiz
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Hi Braiz,

 

the big different is, that if we use IBL, is the hole environment map a Raytracing Light. If we use the 3dsmax daylight system, is the Light splittet in two algorithm: in FG Rays (Environment), and Direct-Area Raytracing Light (Sun). This make problems between Sun and Environment Light.

 

look at the rendersummery:

 

- 12 am look the ground bright, because the Sun have a real energy. And important is, the ground looks white, and not blue/gray.

 

- 3pm to 5 pm looks the Reflection of 3dsmax daylight to bright. The IBL Reflection looks correct to the environment light.

 

- all IBL Renderings have more contrast in the tiny areas of the Camera, because the IBL generate real Raytrace Shadows and not FG-Rays.

 

- the Shadow of 3dsmax daylight system can you tweak with smooth Function. In IBL Mode Mode must we use sun_glow and sun_scale, at the mia physical sky shader.

 

 

comming soon... I create a Workflow of "IBL generate Photons" (GI + Caustics) and present it tomorrow at the same blog.

 

Yes! IBL is slower as 3dsmax daylightsystem, but if you have a indoor Scene, with many Windows (portal lights), is IBL faster and you can deactivate all "Environment Fake Light" (Daylightsystem + portal Light)

Edited by thorsten hartmann
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I see.. It makes perfect sence.

So I should disable my portal lights for an interior scene, and only use IBL, am I right??

 

Another thing... I know that the arch & design material doesn't support IBL. I remember you had a work around for that??

 

One last thing.. Should one be using IBL + FG or IBL by it self?

Edited by Braiz
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- yes for indoors can you deactivate portal light, because IBL + Portal Light are Raytracing Lights.

 

- i have a work around. I convert with Shader Utilities (Free Version can do that) all A&D Materials to a TH-Generic and set under Light-Properties the Light Mode Value to "all+IBL". look here: http://www.infinity-vision.de/page/ibl_mode#ibl_mode

 

- IBL is only a Raytracing Light, that create only indirect light if you use photons. FG can read IBL-Photon and use it for the FG-Map.

 

I use...

 

- outdoor: IBL + FG

- indoor: IBL + Photon + FG

 

if i need selfillum materials...

- outdoor: IBL + Importon + FG

- indoor: IBL + Importon + FG

Edited by thorsten hartmann
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Alright... I see you have some extra settings for your mia physical sky (sky_luminance_mode, diff._horizontal_luminance, zenith_luminance) compared to the one used in your tutorial (the screenshot shows less options compared to the downloaded one). What does these settings do, are they simular to the CIE/perez sky model??

Edited by Braiz
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  • 1 month later...

Hi Thorsten.. Is there a way to enable photon emition from the environment, without having to use IBL?? I get severe noise in my images when using IBL + Photons + FG for interior shots.

 

But the fact that I don't have to use portal lights is amazing. Plus the light gets distributed nicely. In fact, when using photons with your solution, it seems to give better results then using GI + FG together with the standard daylight system & portal lights.

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Hi Braiz,

 

yes you can emitted Photon from the Environment. But you need two Render steps.

 

Step 1: Render only the Photon Map.

- set the IBL-Quality to 10 - 20. The formular is: 5000 (fix) x IBL_Quality_Value. for Example 5000x20=100.000 Photons.

 

Step2:

- set the IBL-Quality normal Value 0.5 - 2. Create now Final Gather and use the Photonmap.

 

This Work for GI + Caustics.

 

mfg

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