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Point lights shining through objects?

SnowSultanSnowSultan Posts: 3,773
in Blender Discussion

Can someone tell me if this is normal behavior for point lights? I have a tiny one (1 watt, 5 cm) on the wick of this candle and yet it's lighting the top outer edges of the lamp that should be blocked by the upper border. Using Cycles, don't think I have anything else weird going on here. Thanks for any information.

Comments

  • PadonePadone Posts: 4,001
    edited August 2021

    Because light bounces and crawls. That is, cycles is photoreal, not a classic raytrace engine with no global illumination. If the top of the lamp gets a separate geometry with some space for the light to pass then it will. Also there's GI.

    Post edited by Padone on
  • SnowSultanSnowSultan Posts: 3,773

    There is virtually no GI in that scene, everything outside of that point light is black. I don't know offhand if there is a break in that geometry at the top, but I've used this before in Studio and never had this sort of issue.

  • FishtalesFishtales Posts: 6,209

    Try raising the light higher on the wick. It looks like it is low enough to shine under the top border rather than the top border causing shadow. Raising the light should cause the light to shine on the border and cause it to shadow on the lip. I should also add it doesn't look wrong to me as, depending on the length of the candle inside the lantern, the light from a real lantern would look similar.

  • TheMysteryIsThePointTheMysteryIsThePoint Posts: 3,220

    It looks like the point light might be reflecting off of the bottom of the inside of the lamp and impinging on the top outer edges. I can't think of a case where I second-guessed cycles and I turned out to be right and cycles wrong.

  • SnowSultanSnowSultan Posts: 3,773

    Sorry for the delay, I didn't have a chance to test that scene again until just now. Nothing I've tried has any effect, and while I also won't second guess Cycles, I think there might be something weird with the geometry or elsewhere. I turned roughness all the way up and moved the light around inside the lamp and that top is as bright as ever. I'm not going to worry about it now, if I needed to render this, I'd do it in two passes and just paint away the light where I don't want it. Tired of trying to get everything right in 3D programs anyway.

    Thanks for the suggestions.

  • stem_athomestem_athome Posts: 526

    SnowSultan said:

    There is virtually no GI in that scene, everything outside of that point light is black. I don't know offhand if there is a break in that geometry at the top, but I've used this before in Studio and never had this sort of issue.

    It looks like you have glass/transparent walls on the prop. What materials are you using for that in DS and Blender? 

  • TheMysteryIsThePointTheMysteryIsThePoint Posts: 3,220

    Are you sure no normals are flipped?

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