How To Create A SEMI Transparent Material? (Frosted Ice)

[Pires]

Hi,

Im trying to create a good ice material for my project. There are a few ice materials available from the LiveDB but they are very transparent. For my scene I need it to be cloudy and semi transparent so it shows up well against the background.

Fair enough I thought, Ill just reduce the 'Opacity' slider so it will become more opaque, but that value seemingly has no impact (can only make it MORE transparent). So then I thought I'd add a diffuse layer, but it appears you cant have both diffuse and transparency layers together?! The 'Roughness' slider helps to some degree, but I have to set it so high to get the desired opacity that it looks really grainy even at high render settings.

Unfortunately setting up materials in Octane seems pretty unintuitive and is becoming frustrating! Would someone be able to point me in the right direction or possibly share a good ice material.

Many Thanks.

[prehabitat]

Ice" material:
reflection 0.930
transmission 1.000
ior 1.299
coefficient dispersion 0.003

From viewtopic.php?f=6&t=51838&p=260103&hili ... cs#p260103

[Pires]

Thanks for the quick reply. I followed your suggested settings (ignoring the coefficient dispersion as it looks weird to me) and got this:




This is unfortunately the opposite of what I wanted - its practically see through and looks more like glass! Imagine when you get an ice cube out of the freezer, its frosty and you cant see straight through it, that is the look I am trying to achieve. Sorry if I didnt make it clearer.

[aoktar]

Unfortunately setting up materials in Octane seems pretty unintuitive and is becoming frustrating! Would someone be able to point me in the right direction or possibly share a good ice material.

This is physical based pathtracer. So you should act to materials as in real world. There is no opacity in world. Also you can't get good looking materials without putting any environment and well modelled/textured objects. Forget opacity, use tranmission/roughness,index,reflection on specular materials. Also try mediums.

Always put some sample images to figure what you want. Good results require some nice details and some tricks.

viewtopic.php?f=5&t=51605&hilit=ice+material
viewtopic.php?f=5&t=50670&p=252204&hili ... al#p252204
https://dl.dropboxusercontent.com/u/674 ... Octane.jpg
viewtopic.php?f=9&t=35487&hilit=ice+material

[Pires]

This is physical based pathtracer. So you should act to materials as in real world. There is no opacity in world. Also you can't get good looking materials without putting any environment and well modelled/textured objects. Forget opacity, use tranmission/roughness,index,reflection on specular materials. Also try mediums.

Hi aoktar. Thanks for the suggestions but I still dont seem to be having any luck unfortunately. When I try adding roughness or dispersion it just makes it look terrible:



It seems like its either transparent and looks good, or semi-transparent and looks awful! I would like it be frosted white and barely transparent so it shows up well against the background.

In my actual scene its one I downloaded from the internet and using 3,000 samples, 6 diffuse and specular depth. Ive included a copy of the project file in the attachment if anyone wants to look (using alpha version 3).

[aoktar]

Any images for your target material?

[Pires]

Any images for your target material?

Sure, just frosted ice like this:








To ultimately get some text like this (not sure about the blue tint, but that can be sorted later):




If anyone could help me achieve a material like that it would be great

[brasco]

To an extent, you have to treat octane materials like real world materials so you need to analyse the photos and work out what's going on physically.

With Ice you have a transparent base that at it's purest form is clear. That can be seen as a basic Specular material here (Refraction / Reflection at it's most basic level).
The volume is clear but the surface can have bumps and also condensation that can look rough, so you'll need bump and a roughness map.

That gives something like this:



Then there's the cloudiness (volumetric). This is caused by impurities in the water that end up clustering together (as the ice crystalizes it traps them in the center). This scatters the light giving you the cloudiness. So you'll need to create a duplicate piece of geometry with a simple scattering medium (diffuse / specular with no index)

Here's the geo flat shaded - Cloudy / Impurities geo (L), Main geo (R):



Combining the impurities with the base gives this:



It will increase the render time a lot since it has to scatter. You can compensate a bit for the loss of energy by having the scatter emit a tiny amount too.
It also means you lose some detail overall since you scatter any contrast in the background, so you may just want to use the surface roughness.


cheers
brasc

[Pires]

Many thanks Brasco, that looks awesome!

Ive sent you a PM

[prehabitat]

Any chance you'll share?