Loading...
> >

Emissive Surfaces in Canvasses?

evilded777evilded777 Posts: 2,482
in The Commons

So how does one light with emissive surfaces, or just use emissive surfaces properly when rendering to canvases?

Comments

  • Oso3DOso3D Posts: 15,087

    Which kind of canvas? Beauty pass is just like regular image...

     

  • evilded777evilded777 Posts: 2,482

    In general, Will.

     

    I remember reading something by tobor (I think) that mentioned something about emissives being difficult.  And well... its seems so.  They seem to cast light in all my canvasses, not just the emissive one.  Which seems like odd behavior....

  • evilded777evilded777 Posts: 2,482
    evilded777 said:

    In general, Will.

     

    I remember reading something by tobor (I think) that mentioned something about emissives being difficult.  And well... its seems so.  They seem to cast light in all my canvasses, not just the emissive one.  Which seems like odd behavior....

    That's not actually the behavior...something is odd.  Try using Render Studio for Iray...you get no light on your emissive canvas.

     

    so I am obviously missing something.

  • KhoryKhory Posts: 3,854

    I think that the emissive layer simply shows the emissive. Not as light but as color. The canvas to get the emissive light itself seems to be light group.

  • evilded777evilded777 Posts: 2,482
    Khory said:

    I think that the emissive layer simply shows the emissive. Not as light but as color. The canvas to get the emissive light itself seems to be light group.

    Really? The simple answer? So obvious, one would not have thought of it?

     

    Thanks, Khory! I'll give that a try

  • ToborTobor Posts: 2,300

    The Emission canvas works backwards to what many people expect. From the nVidia docs:

    Color canvas that contains the emission contribution from directly visible light sources and emitting surfaces in the rendered image.

    What gets displayed is the effect of the emissive, not the emissive itself. If you use nodes to specify the object(s) you want to render, you need to select the scene objects, not the emission surface that casts the light. Otherwise, you can just set None, and you'll get the lit objects, but not the emissive itself.

    Do note that the Light Group canvas provides a finer granularity, as you can define the group, and also renders the light source if it's an emissive if you've selected it in the Nodes list. From the docs:

    All direct and indirect light contribution coming from the key light group, which are all lights in the scene with the handle attribute set to key.

    where key is the light group you wish to work with. See Esemwy's tutorial on it here: http://www.daz3d.com/forums/discussion/62101/relighting-with-iray-canvases/p1

    Note: Be sure to use Photoreal. Emissives won't light objects in Interactive mode.

     

  • evilded777evilded777 Posts: 2,482
    Tobor said:

    The Emission canvas works backwards to what many people expect. From the nVidia docs:

    Color canvas that contains the emission contribution from directly visible light sources and emitting surfaces in the rendered image.

    What gets displayed is the effect of the emissive, not the emissive itself. If you use nodes to specify the object(s) you want to render, you need to select the scene objects, not the emission surface that casts the light. Otherwise, you can just set None, and you'll get the lit objects, but not the emissive itself.

    Do note that the Light Group canvas provides a finer granularity, as you can define the group, and also renders the light source if it's an emissive if you've selected it in the Nodes list. From the docs:

    All direct and indirect light contribution coming from the key light group, which are all lights in the scene with the handle attribute set to key.

    where key is the light group you wish to work with. See Esemwy's tutorial on it here: http://www.daz3d.com/forums/discussion/62101/relighting-with-iray-canvases/p1

    Note: Be sure to use Photoreal. Emissives won't light objects in Interactive mode.

     

    Not getting something here...

    "What gets displayed is the effect of the emissive, not the emissive itself. If you use nodes to specify the object(s) you want to render, you need to select the scene objects, not the emission surface that casts the light. Otherwise, you can just set None, and you'll get the lit objects, but not the emissive itself."

    That part makes my head hurt.

    Using a Light Group Canvas seems to do the trick, but I would like to understand the Emissive Canvas better.  I need to experiment with this new information

Sign In or Register to comment.