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Blackbody emission and one poligon face issue

Posted: Fri Jan 23, 2015 10:02 pm
by dotcommer
Check the screenshots.

I've noticed that if I have an emission from an alpha channel, it looks correct but only from one side. If I were to flip that single polygon face over, I can see the cutout of the alpha, but no blackbody emission. Why is that? Notice in the renders that the surface below the UI is very reflective, so we should be seeing a reflection, but in the first image, you can't. In the second, I've flipped the image over 180˚, and now you can see a reflection, but notice the "top" (was the bottom of this polygon face) is very dim. Is there something I'm not doing correctly in my emission texture?

Using Octane v2.04.1 / C4D R15
Screen Shot 2015-01-23 at 1.48.21 PM.png
Screen Shot 2015-01-23 at 1.48.45 PM.png
Screen Shot 2015-01-23 at 1.54.41 PM.png
Screen Shot 2015-01-23 at 1.55.05 PM.png

Re: Blackbody emission and one poligon face issue

Posted: Fri Jan 23, 2015 11:03 pm
by aoktar
yes, it casts the illumination from front side

Re: Blackbody emission and one poligon face issue

Posted: Fri Jan 23, 2015 11:27 pm
by dotcommer
Is there a way to cast from both sides? My only work-around has been to duplicated the layer, flip it 180˚ and put it slightly below the original.

Re: Blackbody emission and one poligon face issue

Posted: Fri Jan 23, 2015 11:49 pm
by shawnfrueh
dotcommer wrote:Is there a way to cast from both sides? My only work-around has been to duplicated the layer, flip it 180˚ and put it slightly below the original.
Try using a mix material, put the emission material in both slots and use 'side' as the mix. This should add the material to the front and back of the polygons.

Re: Blackbody emission and one poligon face issue

Posted: Sat Jan 24, 2015 12:00 am
by dotcommer
shawnfrueh wrote:use 'side' as the mix. This should add the material to the front and back of the polygons.
What do you mean? I'm not seeing anything like that in the mix material. Just two slots for two materials, and the amount is set to a floatTexture.

Re: Blackbody emission and one poligon face issue

Posted: Sat Jan 24, 2015 12:26 am
by aoktar
This is how the work Octane. Use a thin box rather than plane. You and all guys should look to standalone topics at least sometimes.

Re: Blackbody emission and one poligon face issue

Posted: Sat Jan 24, 2015 12:35 am
by dotcommer
Ah, thank you ahmet. The thin box works perfectly.