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Author Topic: Reflectance question  (Read 3606 times)

M7

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Reflectance question
« on: August 07, 2014, 10:34:26 am »

I'm trying to make sense of the reflectance map. So on this cube, i used an albedo, roughness and a reflectance map.

So what i can observe is that  reflectance map from 0.0 to 0.43 seems to be the full range of a regular specular map. (Im still confused as to how other 3d program call a reflectance map)

 Then over  about 0.43 , it's something else. It becomes a flat value where the albedo is back at 100% and the mirror effect stay full (as it pick up no shadows)

I'm asking cause i want to use specular maps from programs like Ddo (quixel suite). So for these to work as expected, i would have to set the F0 to 0.43 ? I'm sure i'm still missing something...

« Last Edit: August 07, 2014, 11:30:36 am by M7 »
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2eyed

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Re: Reflectance question
« Reply #1 on: August 07, 2014, 10:48:49 am »

There is need  for someone doing documentation and updates therefor.
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angrypig

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Re: Reflectance question
« Reply #2 on: August 08, 2014, 11:04:57 am »

I made update to our wiki page i hope it will help you.

http://xtrac.outerraworld.com/trac.fcgi/wiki/material
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M7

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Re: Reflectance question
« Reply #3 on: August 08, 2014, 12:03:08 pm »

Thanks Angrypig for the wiki update. It doesnt quite clarify the logic of reflectance (especially the break in the value at 0.43)  but just by asking the question, i  got a more clear idea of what i can do with that it. So i'll experiment so more.
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angrypig

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Re: Reflectance question
« Reply #4 on: August 08, 2014, 12:07:51 pm »

There is condition if "f0 > 0.45" then the material is metallic. It will change in the future there will be additional value in the material definition "metallicity".
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ddenn

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Re: Reflectance question
« Reply #5 on: August 08, 2014, 12:35:58 pm »

Maybe better to add additional texture to set "f0"? That way we can combine plastic/metallic parts in one material

P.s. Sorry, just read the wiki. Is reflectance map working already? I missed that somehow
P.p.s Yep, already working. Sorry )
« Last Edit: August 08, 2014, 01:04:43 pm by ddenn »
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M7

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Re: Reflectance question
« Reply #6 on: August 08, 2014, 03:02:52 pm »

So yeah in order to use a reflectance map with tonal values, the F0 have to be set at 0.45 or lower

Here i tried to get some dirt on a chrome surface. Now if i set the F0 to 0.46 , the chrome start to turn  black like on the buttom right image.

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