glass seemingly not transmitting light

dmn · Post by **dmn** » Sat Feb 10, 2007 4:43 pm

When I export a model from blender to Indigo 0.7t4, the glass appears black and does not transmit any light. Even after transferring the exact settings from the 'ior_test.xml' for the glass medium and material, I still get the same result. This makes no sense to me as it works fine in the test scene. I only have sky light for illumination. Do I need a light source other than the sky? Are there other settings that effect the material/medium settings?

zsouthboy · Post by **zsouthboy** » Sat Feb 10, 2007 5:23 pm

Make sure normals are pointed outwards on the glass.

Make sure your sky has a sun in it.

CTZn · Post by **CTZn** » Sat Feb 10, 2007 9:52 pm

Are there other settings that effect the material/medium settings?

Yes, if the glass material has absorption the scale does matter; if your object is 10x bigger you will have one tenth of the light transmitted through, compared with the smaller object.

The doc wrote:absorption_coefficient_spectrum

Controls the rate at which light is absorbed as it passes through the medium.

The thicker the medium, the less light passes through.

scattering_coefficient_spectrum also can cause black materials if it is set too high

dmn · Post by **dmn** » Mon Feb 12, 2007 6:00 am

sorry I disappeared there. End of week distractions.
It appears that when I imported into blender the normals of every object were reversed

The glass is 1/8" and I set the absorption to 0, so it shouldn't effect anything.

dmn · Post by **dmn** » Mon Feb 12, 2007 6:06 am

I ended up going back into my modelling program and exporting with normals export disabled, and now the blend file is correct. With normals all pointing outward, Indigo is rendering the glass as transparent. I think, really, I need to figure out Blender's modelling system so I don't have to go back and forth

Thx for the help.

don't suppose anyone knows of a command in blender to 'recalc normals outside' while in object mode with all objects selected?

Lord of the Rings Junkie · Post by **Lord of the Rings Junkie** » Sat Feb 24, 2007 5:36 pm

CTZn wrote:
Are there other settings that effect the material/medium settings?
Yes, if the glass material has absorption the scale does matter; if your object is 10x bigger you will have one tenth of the light transmitted through, compared with the smaller object.

Any tips on how to scale things in Blender to get them right in Indigo? (i.e. 1 BU = _____ real world units)

zsouthboy · Post by **zsouthboy** » Sun Feb 25, 2007 2:07 pm

1 BU = 1 m in Indigo
per current exporters

glass seemingly not transmitting light

glass seemingly not transmitting light

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