Dumb question time: Turn an existing object into an area light?



  • Say I have a purchased scene with a lamp, separate light bulb modeled in the lamp. Can I turn the light bulb into an area light and how would I do that?



  • @Glitterati3D turn up ambience in the material and that will turn the light bulb model into a mesh light. You can experiment with different ambience settings for brighter lights.



  • @ghostship OK, thanks. These lights had ambience turned up, but I wasn't sure if that was the way it should be handled. The scene was not created for and was released before Superfly.

    I just EZDome and one spot light in this render in Superfly.

    0_1479840385088_EZDomeInteriorSuperfly.jpg



  • for a more natural look you would turn off any Poser lights like the one casting that sideways shadow in your image. Just let the mesh lights light up the scene along with the skydome or background picture you are using for behind the window.



  • @ghostship Yeah, I meant to delete the spotlight and forgot. But, that shadow is coming from a window behind the couch. There's a kitchen window back there emitting light from the EZDome (winter scene).



  • @Glitterati3D that sharp shadow is not coming from a mesh light. (the sky dome is a giant mesh light). I'd love to see a render with the spot light off.


  • Poser Ambassadors

    Turning up the ambient produces a white-hot object but only casts light weakly.

    The trick is to get the apparent brightness of the object to match the strength of the light cast.

    Give me a bit to whip up a demonstrator.



  • @ghostship said in Dumb question time: Turn an existing object into an area light?:

    @Glitterati3D that sharp shadow is not coming from a mesh light. (the sky dome is a giant mesh light). I'd love to see a render with the spot light off.

    Rendering it now, but it's gonna take a while - it's very noisy.



  • @seachnasaigh said in Dumb question time: Turn an existing object into an area light?:

    Turning up the ambient produces a white-hot object but only casts light weakly.

    The trick is to get the apparent brightness of the object to match the strength of the light cast.

    Give me a bit to whip up a demonstrator.

    Thank you, seachnasaigh! I would appreciate you doing so.



  • @ghostship Here it is at the same samples as the one with the spot light. As you can see it's very noisy and dark. Which is why I wanted to know how to turn those bulbs into mesh lights.

    This is just EZDome and the ambient turned up on the lights.

    0_1479851400150_EZDomeInteriorSuperfly2.jpg



  • @seachnasaigh said in Dumb question time: Turn an existing object into an area light?:

    Turning up the ambient produces a white-hot object but only casts light weakly.

    The trick is to get the apparent brightness of the object to match the strength of the light cast.

    Yes, that's exactly what I discovered. The object (a lamp shade for instance) burns so brightly that you lose all form, but it is still not powerful enough to naturally illuminate a scene. I would usually put a point light inside a lamp shade, AND add low level transparency to the shade but then the unrealistic construction of the shade will cast undesirable shadows.



  • @Glitterati3D dark as it may be I think it looks 100x better without the Pose light. We'll get some answers from @seachnasaigh or maybe @piersyf will chime in.



  • @ghostship I can't tell, honestly. It's too dark and too grainy to come to any conclusion.

    And the light bulbs just look stupid - not at all realistic.



  • The one problem I see is that unless it's night outside, the light coming in through the window is very weak and diffused. Walls, floors and ceilings will also reflect the light in a room.



  • Another massive problem with using the ambient light type - no control over the light falloff model!


  • Poser Ambassadors

    This Superfly prop is two-piece; place the mount base against the ceiling, then select the lamp and Y-translate it up/down to fit the scene.

    Superfly lightcaster lamp

    In the Superfly render settings, set mesh light samples to 15. Use a couple of subsurface samples for the shade.

    Here is the material for the lamp bulb, a soft pink light. Adjust strength of lightcasting by lightening or darkening the color box indicated. Light grey will give modest boost; dark grey will cast strong light. The lampshade can be separately adjusted, but it should respond to the mesh light.
    0_1479854726543_demo lamp bulb mat.PNG

    For your situation, with a modest number of lamps, I recommend using both a point light within the bulb and the mesh light technique; just make the point light weaker and lessen the mesh light boost (lighten the color box). The combination looks better than either method used alone.
    Be forewarned that the more you must rely on meshlighting, the more mesh light samples -and therefore more render time- will be needed.

    For scenes with a lot of lights (Atlantis, Lothlorien) use only the mesh lighting.

    P.S. The light falloff for a mesh light will be inverse square.


  • Poser Team

    Keep in mind that Superfly is a reverse path tracer. The render engine needs to find light on as many ray casts as possible.

    I would add a plane to it, just outside the window. Set it to be invisible, and turn up the ambient so the engine finds light from that source.
    There are two advantages to this, you can select the color light you want, and the amount cast.

    You can do the same thing with the lamps as well. Set the ambient on the bulb where the bulb looks right, then do a lightpath setup on the shade where it casts light without blowing it out. You end up with far more light being cast, without blowing things out.

    Here is a very simple Poser scene to demo a hidden emitter. 0_1479855313113_hidden emitter.zip.txt Rename and extract.

    As far as controlling the fall off rate of these lights, that can easily be done in any scene with a cube and a volume absorption node.


  • Poser Ambassadors

    Oh, more user info...

    Adjust the brightness of the lamp itself with the root node's ambient_value.

    That color block in the bulb material is for adjusting the ratio of apparent brightness to lightcasting strength.

    For light coming in through the windows, I have lightcaster materials for the P11 "construct" skydome.

    P11 construct material sampler


  • Poser Ambassadors

    Rough render test, mesh light only for the lamp (no point light inside).
    0_1479857830398_demo lamp rough test.png



  • @seachnasaigh

    Interesting solution!
    Till now, I was using a mat setting created by Bagginsbill with two spots by lamp, to avoid the too luminous point below the lamp.
    Furthermore, I cannot set the mesh light samples as I render most of the time with the GPU.
    With two spots per lamp + one big area lamp near the ceiling, oriented towards the ground, to control the overall light of the room, that gives this:

    alt text

    In case someone is interested in BB's lamp shade setup:
    alt text
    Downloadable here.


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