Best Lights (realistic) : how to in Mantra?

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Hello,
( This is a 3 part post i couldn't post more than one image in a message)

I'm trying to find out the best way to lightning as real as possible.
I have some questions with houdini Mantra lights.

So i already did some testing with a simple scene



and i have a few questions regarding those coming Renderview screenshots.
Edited by arnold_FR - April 1, 2019 02:26:47

Attachments:
intro.JPG (66.9 KB)

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This is a geo light, it takes a geometry object as reference, in this case it's the geometry of a light,
i added a link to a 32bit linear texture in the Texture map file chooser.

Attachments:
geolight.JPG (27.3 KB)

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This is shader emissive light, a geometry object which imports the geo of the light + a principled shader is applied to it,
the principled shader is blk and has no reflection or so, only it's an emmisive mat with a texture in emissive channel /
this is the exact same 32bit texture as the previous example.






Why are those renders so different ?
same texture applied, same intensity.
Are the textures from geo lights interpreted as srgb > not linear as default ?
or is there a gamma difference at default ?
the render looks washed out.
To me the shader applied to geometry with emmissive texture is the realistic one (highlights & shadows are defined),
and it feels more close to what i get in studio, but whatever i tried, i cannot get to similar result using the geo light :
geo light has samples parameter but shader light don't this is why i'd prefer to use geo light.
Edited by arnold_FR - March 31, 2019 13:20:14

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shaderLight.JPG (197.6 KB)

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I've noticed i can't apply kelvin colors to the lights (non sense) so i tried a workaround,
tell me if it's okay to do like that or if there's something more simple




In fact i've shot most of my studio flash light modelers as 32bit linear textures for the purpose of getting similar results from studio to 3d scene : what is the best process for this inside Mantra ?
what is the best process to get real lights inside houdini ?


Thanks a lot for your help,
++
Edited by arnold_FR - March 31, 2019 13:22:17

Attachments:
kelvin-to-rgb.JPG (62.9 KB)

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