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Iray Emission question.

AndroolAndrool Posts: 85
in Technical Help (nuts n bolts)

Is it possible to make an emiter who is invisible in the render but still emit light?

I used to make my floors lightly emiting in blender to fasten the render but not becoming brilliant themself. I'm wondering if you can do it with Iray

Comments

  • IsaacNewtonIsaacNewton Posts: 1,300

    That would be a useful little trick, but I suspect as Iray mimics real light behaviour the only way to have an invisible emitter is to have it out of shot. Maybe someone knows how to get around this? 

  • mjc1016mjc1016 Posts: 15,001

    For photometric lights, there is, in their parameters, an option to 'Render emitter'.  Turning this off will not render the light, but still cast the light.

  • AndroolAndrool Posts: 85
    edited November 2016

    Thanks, I'll try to find the switch. ^^

    Edit: I don't see it in the emmission category.

    I only have *two sided light* with an on off option

    Edit 2: ok photometric light are light we can add I guess. so I canot exactly do the same but I can add unvisible photometric lights. Well no clue how these light will work the same. The base idea in blender was since the floor is very large, even with a low emmitance it will reduce the grain everywere a bit, living nothing in hard shadow. Since what I try to do right now has more to do with having a back light without having burning points in my scene atracting the eyes I guess photometric light will be perfect.

    Post edited by Androol on
  • mjc1016mjc1016 Posts: 15,001

    You can adjust the size of the photometric light and give it a 'shape' too...using a point light set to rectangle and more than a meter in size (the units are cm, so that would be greater than 100 x 100) would be perfect for that...just make sure it's pointing the right direction (you'll probably need to play around with the orientation once you make it a rectangle).

  • JD_MortalJD_Mortal Posts: 760
    edited November 2016

    Turn a surface into an IRAY "Emissive" surface, then set the "Cutout Opacity" to a value of "0.0000001" (It can go lower... but it will show as 0, but it is not "0"... ("0.00000000001" is the lowest non-zero value you can use. Iray accepts larger floating-point values than Daz3D likes to display.)

    Also, if it gives you trouble... (These defaults are non-zero for emissive surfaces.)

    Glossy Layered Weight = 0.0

    Glossy Reflectivity = 0.0

    Refraction Index = 1.0 (1 is the lowest)

     

    The light will be essentially invisible, but emittance will be 100%.

    Emissive-1.0.jpg
    764 x 600 - 138K
    Post edited by JD_Mortal on
  • nonesuch00nonesuch00 Posts: 18,120

    Oh, it looks like I can use that 0.00000000001 to solve a different problem I wanted to do for my render.

  • nonesuch00nonesuch00 Posts: 18,120

    WooWoo...that and a duplication in place of the models I am using allowed my to create the ghost effect I wanted. Thanks very much.

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