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Unwanted light geometry showing up in render

RacerDCRacerDC Posts: 50
in Technical Help (nuts n bolts)

Hi all,

I have a problem with the render on photoreal.  I'm using a simple photometric spot rim, Lumin 75000, Temp 7500, Render Emitter Off, Two-Sided Off.  And every time I render, the light source comes up as a disc (because I selected Light Geometry as disc, or rectangle or sphere.)  I killed the light, then created another at the same intensity and position and again it happened.  With the Render Emitter in Off position, only the light should appear but not the geometry.  So what gives?  Any suggestions?

Just can't get that sphere/disc/rectangle to disappear.  Never happened before til now.  Please see attached.

 

Test.png
1661 x 1328 - 5M

Comments

  • Richard HaseltineRichard Haseltine Posts: 102,797

    Render Emitter Off hides the light from direct view, but ti will still show in reflections and viewed through a surface - in this case, I assume there's mesh in the window and that's what is triggering the light to show. Using an emissive surface on a model and setting the Cutout Opacity to a very low, but non-zero, value may be the answer - butt hen the light will also fail to contribute to specular effects as it isn't reflecting. The other option is to move the light so it's either hidden by the wall or is inside the model (but not behnd the hair, which will have the same issue).

  • RacerDCRacerDC Posts: 50

    Thanks, Richard, always the simplest option is best.  I'll move the light.  Or maybe use a distant light with very very low photometric intensity.  

  • PaintboxPaintbox Posts: 1,633
    edited August 2018

    You could consider using the ghost light kit. Its always invisible.

    https://www.daz3d.com/iray-ghost-light-kit

    Post edited by Paintbox on
  • JonnyRayJonnyRay Posts: 1,744

    Another thing you could do with that render is just remove the glass surface (set opacity to zero). It isn't really serving any purpose in that render and you can keep the lighting just the way you have it now.

  • RacerDCRacerDC Posts: 50

    Thanks all, I have ghost lights, just didn't occur to me to use it.  That's what happens when you buy too many products and forgot what you have.  Will try.  And I'll try setting the glass surface opacity to zero too.  Good options, everyone.  Thanks 

  • PaintboxPaintbox Posts: 1,633
    RacerDC said:

    Thanks all, I have ghost lights, just didn't occur to me to use it.  That's what happens when you buy too many products and forgot what you have.  Will try.  And I'll try setting the glass surface opacity to zero too.  Good options, everyone.  Thanks

    Pretty cool shot / scene btw you've created, very creative

     

  • RacerDCRacerDC Posts: 50

    Appreciate the thumbs up Paint.  I hope to have the final-final render out on the Gallery soon -- my first.

  • ToborTobor Posts: 2,300

    I would also simply remove the glass and use the spotlight, which is providing some nice specular effects. You'll lose that with a mesh light, as Richard notes, unless you add an IES profile. (They're free from various light manufacturers; try a few someday when you get the chance.)

    Avoid the distant light unless you're okay with the heavy shadow. The distant light is a pinpoint at an infinite distance away, so its rays are parallel, and therefore create sharp shadow outlines. Which is great for some things, but not for others.

  • y3kmany3kman Posts: 802

    Speaking of spotlights, is there an easy way (script?) of converting them to emissive planes?

  • fastbike1fastbike1 Posts: 4,078

    However, as Richard said, "the light will also fail to contribute to specular effects as it isn't reflecting"

    Paintbox said:

    You could consider using the ghost light kit. Its always invisible.

    https://www.daz3d.com/iray-ghost-light-kit

     

  • RacerDCRacerDC Posts: 50

    Agreed Tobor, the distant light had marginal effects if the intensity is set too low, and harsh shadows if too high.  Sure you could take it off photometric and mess around with it for a while.  I tried to reduce the glass to 0 opacity also and it still didn't work.  The best and simplest solution from Richard was to move the light.  I pitched it below the car door and tilted it up at an angle, had to z-rotate the rig a little for the best angle.  But there it is -- a 5 cent worth solution to a head scratcher -- move the damn light.  Thank Richard.

  • ToborTobor Posts: 2,300
    RacerDC said:

     Sure you could take it off photometric 

    FWIW Dept: Photometric only relates to the color perception related to human vision. Rather than treating the full spectrum equally, the apparent intensity of the light varies based on our human vision where green/yellow-green appears brightest. Some folks think it alters other physical aspects of the light, such as falloff, but this not the case. For distant light there is no falloff, and . It's treated as an infinite source, like the sun. There's only a few settings you can make with the infinite light anyway, and fewer still if you turn Photometric off.

    None of this has anything to do with why you see the emitter when the light passes through geometry, even if the geometry is invisible. I think that like reflections, it's an intentional feature of Iray. It would be great if we could have a second option that says Render Emitter No Matter What, and chose On or Off for that.

    y3kman said:

    Speaking of spotlights, is there an easy way (script?) of converting them to emissive planes?

    Maybe someone has written such a script for the general orientation of the mesh in relation to the direction of the spotlight, but the light from a mesh source won't be anything like the original spotlight.  

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