Dichroic filters - Can they be created in any Thea Render engine?

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nigec
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Sun Mar 08, 2020 10:37 am

ok, you are using Sketchup yes?

there's actually a procedural , that could be used as a mask
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DavePSB
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Sun Mar 08, 2020 11:55 am

Don’t know if it’s supported in 2.2, but here are some screen shots from an old 1.5 manual that looks very promising..
C7C0E1F2-EDE2-46A0-921A-154472FC630E.png
72AE158B-2EE9-45BC-B5DB-DC906E5B2475.png
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DavePSB
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Sun Mar 08, 2020 12:49 pm

Here's a working solution, but done with SU2015 and Thea 1.5 (using Mat Lab).

Use a glossy material

Render in AMC (Presto gives odd colors). TR1 or TR2 would probably work.

I found by trial and error that an extinction coefficient of 2 gave a nice effect

You can soften the transition between colors by smoothing out the step in the fresnel curve

I couldn't find the screenshot I posted earlier from the manual (ie, I don't find the RGB curves option etc), so maybe that was an earlier or later manual. But this is working.

I think the black glass is a matter of increasing tracing steps somewhere.

Had to video at low res and frame rate to get board to allow upload.

This looks like it will be fun to play with.
DichroicSmaller.mp4
(2.54 MiB) Downloaded 23 times
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Sun Mar 08, 2020 12:51 pm

Here's the 2015 SU file I used for above video.
DichroicTest.skp
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pbacot
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Sun Mar 08, 2020 4:52 pm

I get some interesting effects by decreasing the abbe number. It really bogs down my computer and I'll probably never see clear image. Thank you! It was worth a try and I learned something about Thea materials.
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Sun Mar 08, 2020 4:57 pm

DavePSB wrote:
Sun Mar 08, 2020 12:49 pm
Here's a working solution, but done with SU2015 and Thea 1.5 (using Mat Lab).

Use a glossy material

Render in AMC (Presto gives odd colors). TR1 or TR2 would probably work.

I found by trial and error that an extinction coefficient of 2 gave a nice effect

You can soften the transition between colors by smoothing out the step in the fresnel curve

I couldn't find the screenshot I posted earlier from the manual (ie, I don't find the RGB curves option etc), so maybe that was an earlier or later manual. But this is working.

I think the black glass is a matter of increasing tracing steps somewhere.

Had to video at low res and frame rate to get board to allow upload.

This looks like it will be fun to play with.

DichroicSmaller.mp4
Thank you, that looks really cool. I'll see what I can do in 2.2.
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Mon Mar 09, 2020 2:30 pm

Here is a working Dichroic glass in SU2017 with Thea2.2 and PrestoMC:
DichroicRedBlue_SU17_TheaV2.skp
(530.35 KiB) Downloaded 22 times
DichroicRedBlue_SU17_TheaV2.jpg
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Tomasz (Mon Mar 09, 2020 3:17 pm) • nigec (Mon Mar 09, 2020 4:53 pm) • Hieru (Wed Mar 11, 2020 2:27 pm)
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nigec
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Mon Mar 09, 2020 4:52 pm

With the Worley Noise you can get a similar look to the reference picture, you also get the similar shadows if its illuminated inside (AMC/TR1/2)
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Tue Mar 10, 2020 10:37 pm

One more. Fun stuff.

A single material (one glass layer) with fresnel RGB curves used for both transmittance and reflectance.

SU2017, Thea v2.2x
DichroicOrangeYellow_SU17_TheaV2.png
DichroicOrangeYellow_SU17_TheaV2.zip
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Win 10
i7-9700K,3.6GHz,32Gb,
RTX2060Super, 8Gb, 442.19
SUMake2015 (15.3.331)
TheaForSU (1.5.09.547.1462)
Thea Studio (1.5.09.1462)
SUMake 2017 (17.2.2555)
TheaForSU (2.2.954.1860)
Blender 2.79, Plugin 1.5.8.760.1455
Blender 2.8x
Revised 14 Feb 2020
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