Author Topic: Glossy Paper material with reflectivity for dark ink  (Read 1436 times)

2018-04-17, 13:16:59

mccuskerj

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Hi,

I'm trying to make an ultra-realistic glossy paper material shader to use for a preview of an open printed book. I'd like there to be higher reflectivity for printed dark ink heavy areas – which tends to be the case in reality if you look closely.

I've been using the Corona Layered shader with a grayscale texture map of the dark ink areas in the Reflectivity channel of one shader  – which would then be plugged into a layered shader along with the image of the printed book page loaded into the diffuse channel of a bottom level shader – but am unable to get much happening.

Any ideas out there? – seems relatively straightforward.

Thanks!

2018-04-17, 13:22:35
Reply #1

tomislavn

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Could you give us some example of an effect you are trying to achieve?
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2018-04-17, 14:06:28
Reply #2

mccuskerj

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Maybe these two images show what I'm trying to describe. Basically the ink is reflective and the paper is actually quite matte. So where there is less ink you get the matte of the paper coming through.

Would love to figure out how to get the kind of iridescent shine on the ink along with a bit of fibrous paper texture – maybe a car paint shader to start with?

2018-04-17, 15:07:27
Reply #3

tomislavn

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Hmm, maybe using Thin Film in reflection slot of Corona material with multiply over standard reflection color could work. You would have to play a little bit with thin film thickness and IOR to get the desired effect.

Here is a quick test with normal texture in diffuse, reflection white with glossiness 0.8 and added thin film into reflection texture slot (multiply 0.8) Thin film thickness at 350nm and IOR 1.5

Tweaking IOR and thickness through interactive render gives you various amount of results that you can check until you find what you need :)

Lightning is a single HDR only.

Also, you can use Corona Layered material and have one mat for the reflection and another one for the base if you prefer (I have set it up like that in my test scene that I have posted in last post).
« Last Edit: 2018-04-17, 15:29:55 by tomislavn »
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2018-04-17, 15:20:23
Reply #4

mccuskerj

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Looks pretty dern good, thanks! Now I just have to switch from C4d to 3ds Max... maybe it's time to learn both.

2018-04-17, 15:22:38
Reply #5

tomislavn

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Looks pretty dern good, thanks! Now I just have to switch from C4d to 3ds Max... maybe it's time to learn both.

No, no, no :) This is Corona for C4D! If you like it I can send you the scene that you can play with (it's C4D R19 though). You can use C4D's native Thin Film texture, it's working great with Corona.
« Last Edit: 2018-04-17, 15:33:50 by tomislavn »
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2018-04-17, 15:23:47
Reply #6

mccuskerj

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Nice! Would be much appeciated!

2018-04-17, 15:28:17
Reply #7

tomislavn

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Nice! Would be much appeciated!

There, a simple scene that I used for testing. You will have to plug some HDR map into light material for the sky since I didn't send you mine (was around 150mb). Updated the scene with Corona Layered material (1 base, 1 reflection mat) for easier management.
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2018-04-17, 16:52:54
Reply #8

sprayer

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do not forget to add small bump

2018-04-17, 20:25:09
Reply #9

mccuskerj

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Thanks, this is perfect. I'll share results once I get there :)

2018-04-17, 21:01:41
Reply #10

Njen

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Just a note that for physically accurate materials, all dielectric materials should always have 100% white reflectivity. It all comes down to adjusting the glossiness and bump. If you have set reflectiveness to anything other than white, then you are effectively telling the shader to reflect back less energy (light) than it is receiving, which goes against the theory of energy conservation where a surface should not reflect more or less energy than it receives.
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2018-04-17, 22:02:08
Reply #11

tomislavn

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Just a note that for physically accurate materials, all dielectric materials should always have 100% white reflectivity. It all comes down to adjusting the glossiness and bump. If you have set reflectiveness to anything other than white, then you are effectively telling the shader to reflect back less energy (light) than it is receiving, which goes against the theory of energy conservation where a surface should not reflect more or less energy than it receives.

Exactly :) That's why I added white reflection material with 75-80% multiplied thin film texture over it to simulate the effect. Anyway, glad that we got this sorted out :)
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2018-04-18, 00:50:22
Reply #12

beanzvision

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