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static lighting won't illuminate translucent material

after light bake, the translucent object is completely black. i have translucent rings for a star. these won't be illuminated. i tried a static light and all meshes are also static.

object has lightmap uv's (correctly routed), is set to cast shadows, material is set to default lit and TLM surface point light is set to "cast translucent shadows"

what do i oversee?

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asked Oct 08 '14 at 03:15 PM in Rendering

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[PB]Aphexx
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hi eric thx for your help! yesterday i found the reason. it was the scene scale. since i use a point light and the planet is about 5km away, the point light refuses to work properly at these distances (attenuation set to 6km, falloff turned off, 15 intensity) when i put the planet only 1km away, then the lighting will appear as also the shadows. but flying away with the cam will remove the lighting from the translucent object. so i think i have to switch to a directional light that is placed at 0,0,0 and that will follow the ships/camera location. this way i might have no scale issues as also access to the cascaded shadow map parameters.

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answered Oct 15 '14 at 02:46 PM

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[PB]Aphexx
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Hey [PB]Aphexx -

Translucent objects should only be visible based on what is reflecting and refracting upon their surface. So, you will want to look at your refraction settings and ensure they are what you want (typically a good range is a LERP between 1 and 1.4 based on a Fresnel input, with a normal if you are using one). You will also want to make sure that your have a roughness of 0 and a metallic of 0, this ensures that the object will get the appropriate physically-based material settings for a translucent object. Finally you want to make sure your scene can accept reflections correctly. You will want to add a Sphere Reflection Capture Actor and increase its bounds to encompass the reflect-able environment. In addition, you will want to go to the World Settings and under Lightmass and the advanced drop down, change the Environment color to something besides black. Even if you are doing a space scene in which the background is black, the reflections need a value besides 0,0,0 to correctly display the reflections. For Example, for a space scene I might start out with a 0.5,0.5,0.5 grey color and work downward until I get the look I am after.

Hopefully this helps you out, but if you are still having problems please let me know -

Thank You

Eric Ketchum

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answered Oct 09 '14 at 02:22 PM

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Lovecraft_K ♦♦ STAFF
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avatar image [PB]Aphexx Oct 09 '14 at 02:43 PM

thank you very much eric! i'll try this and will post if it worked!

avatar image [PB]Aphexx Oct 09 '14 at 11:04 PM

hi eric, i tried all this, but the planet rings won't even be lit the slightest bit. they are only lit when i set the material to masked, but that is not suitable for this object. i did all of the above. perhaps there is still something wrong. i can make the rings emissive, but then they won't receive shadows, or is this possible?

avatar image [PB]Aphexx Oct 09 '14 at 11:05 PM

alt text

here is a picture of the planet

i also tried to set "Translucency Directional Lighting Intensity to 10" but that didn't work either.

avatar image Lovecraft_K ♦♦ STAFF Oct 14 '14 at 07:25 PM

Hey [PB]Aphexx -

Can you upload a screenshot of the ring's material? I want to try to test this, but I want to start from the same place you are.

Thank You

Eric Ketchum

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