Author Topic: ComplexFresnel Texmap  (Read 37456 times)

2015-04-27, 03:02:50

Siger

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Beta version released. Quick presets test (used same glossiness value for all materials (exl. Chromium) only for testing purpose).
Tested with V-Ray 2.x.x, 3.x.x, Corona Renderer 1.x.x, Default Scanline

Based on OSL shader code by Vlado (Chaos Group): http://docs.chaosgroup.com/display/OSLShaders/Complex+Fresnel+shader#

Installation instructions included.

2015-04-27, 03:27:32
Reply #1

oncire

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thanks!

2015-04-27, 17:27:26
Reply #2

steyin

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I assume this is like Grant's method of adjusting the colormap graph, but instead you can insert the exact values for RGB based off the wavelength charts?

2015-04-27, 23:47:59
Reply #3

Siger

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Texmap calculate own fresnel for each wavelength. If you put texmap in the Corona material reflection color slot - don't forget disable material fresnel calculations (enter 999) :)

2015-04-28, 09:52:03
Reply #4

romullus

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Hi Regimantas, is it possible to add ability to save own presets or we have to go with map / material library route?

Didn't have much time to play with it, but i find results rather strange. But of course more tests is needed to draw some conclussions.
I'm not Corona Team member. Everything i say, is my personal opinion only.

2015-04-28, 17:02:10
Reply #5

gabyanz

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Any chanche to have it for max 2012?

I'd like to play with.... since I've read the Viscorbel article...


tnx
Gaby

2015-04-28, 20:45:02
Reply #6

fco3d

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So... how do I use this?
If I go to that website link I only get one value for n and k, I can't find anything that tell me the RGB parts,
also if I compare the presets values with the info in that website, they look different.

Any ideas?
Thanks.

2015-04-28, 21:42:57
Reply #7

steyin

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So... how do I use this?
If I go to that website link I only get one value for n and k, I can't find anything that tell me the RGB parts,
also if I compare the presets values with the info in that website, they look different.

Any ideas?
Thanks.

The RGB wavelength values are taken as the median of their ranges typically. If you look up red on wikipedia for example, its range is 620-740, so the 650 value used in the map is an approximation of its average. You would then find that number for each color, and input it into the wavelength box on the refractive index page.

For example (the copper values), inputting the R value of .65 gives you an n=.27105 and k=3.6092, hence the .271 and 3.609 in the map. Inputting the same RGB wavelength values under a different material from the index pull down will give you the corresponding n and k values for that material (ie: for aluminum, R value of .65, n=1.3424, k=7.4737, which aligns with the values on the fresnel map)

These are estimated numbers of course, not exact values.

2015-04-29, 01:08:50
Reply #8

Siger

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Another experiment ;)
I try to develop a Texmap plug-in which reproduces the effect of thin film interference on a surface.
It is based on code: http://www.gamedev.net/page/resources/_/technical/graphics-programming-and-theory/thin-film-interference-for-computer-graphics-r2962
Plugin will be free and compatible with Corona Renderer.

2015-04-29, 01:21:57
Reply #9

fco3d

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So... how do I use this?
If I go to that website link I only get one value for n and k, I can't find anything that tell me the RGB parts,
also if I compare the presets values with the info in that website, they look different.

Any ideas?
Thanks.

The RGB wavelength values are taken as the median of their ranges typically. If you look up red on wikipedia for example, its range is 620-740, so the 650 value used in the map is an approximation of its average. You would then find that number for each color, and input it into the wavelength box on the refractive index page.

For example (the copper values), inputting the R value of .65 gives you an n=.27105 and k=3.6092, hence the .271 and 3.609 in the map. Inputting the same RGB wavelength values under a different material from the index pull down will give you the corresponding n and k values for that material (ie: for aluminum, R value of .65, n=1.3424, k=7.4737, which aligns with the values on the fresnel map)

These are estimated numbers of course, not exact values.

Thank you for the explanation, now it make sense.

2015-04-29, 10:14:13
Reply #10

Siger

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Any chanche to have it for max 2012?

I'd like to play with.... since I've read the Viscorbel article...

tnx
Gaby

Unfortunately, lower than 2013 it isn't planned.

2015-04-30, 01:57:17
Reply #11

Siger

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Small ThinFilm texmap test.
Works perfectly for Corona Interactive - it is possible to experiment up to infinity... :D

2015-04-30, 10:57:50
Reply #12

maru

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2015-04-30, 12:09:52
Reply #13

pokoy

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The thin film tests look good!

2015-04-30, 12:26:26
Reply #14

dubcat

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Small ThinFilm texmap test.
Works perfectly for Corona Interactive - it is possible to experiment up to infinity... :D

Love it !
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