Author Topic: Blur effect behind glass  (Read 1894 times)

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Offline freaky6

Blur effect behind glass
« on: June 07, 2019, 08:48:47 am »
Hi everyone,

this is my first posting here and I have a question.
Is it somehow possible to create a material (glass) which makes everything behind the glass looking blurry?
Please look at the attached photo for an example. I did this with photoshop, but I want to do it with Keyshot.

Thank you.

Offline andy.engelkemier

Re: Blur effect behind glass
« Reply #1 on: June 07, 2019, 01:03:23 pm »
Yeah, not sure why they wouldn't have built this one in one of the easier shaders.

Change to advanced material.
Diffuse = black
Specular = close to white, try RGB 229
Roughness is your Outside roughness. If you don't change that, it will render faster (slightly) but usually looks odd if something is clearly rendering.. Try something like .001-.002 if needed.
Change specular Transmission to white for 100 transparent. If it's truly glass, just go with that. This material won't be physically correct so that's fine.
Here's the important one. Roughness Transmission. Start with .01. Scale matters, but it looks like that'll be pretty close to what you've got. Theses are Small numbers. So start with that.
Leave Fresnel turned on, or...well, you'll see. You need that on.

Samples. If you're using real-time render, this won't do anything. But if you're using custom control (usually faster) then if this material is the Only material that seems noisy, you'll control that here. The samples under the render settings is global. If this one is higher than the global setting, then it'll override that. If you have to go over something like 128 then there's Likely something else causing the issue.

Now, you're Likely to encounter one more issue, if this is your scene. Keyshot isn't great at looking through glass when it comes to shadows or global illumination. Caustics are great, but you Really don't want to have to calculate caustics through a flat piece of glass to get a decent render.

You can turn the shadow Off for that material using one of the experimental features. Use the forum to find out how to turn those on.
Go into the material graph.
Right click > Utilities > Ray Mask. Plug that into opacity.
Disable Visible Shadow and Visible GI. Those things can ignore it.
You'll notice the inside of your box brighten Right back up, as if it weren't there.

Offline DMerz III

Re: Blur effect behind glass
« Reply #2 on: June 07, 2019, 01:26:41 pm »
 :) The Dielectric shader is the other option it works very similar to the solid/glass and gem shaders but has the option for roughness transmission, which will keep the outer surface 'glossy' and internal bounces (within the 'glass') will be 'scattered'.
You will need to have a 'thickness' modeled into your pane though, should be a solid not just a single surface.
See screenshots.

« Last Edit: June 07, 2019, 01:30:39 pm by DMerz III »

Offline freaky6

Re: Blur effect behind glass
« Reply #3 on: June 07, 2019, 02:18:31 pm »
I can not thank you enough. I tried both methods and they are working very well.
I should have asked earlier... was trying by myself since 2 days and did not make it.

btw: the tip to disable the visible shadow and GI in the experimental settings was also great!

Thank you so much for your effort!

Offline andy.engelkemier

Re: Blur effect behind glass
« Reply #4 on: June 10, 2019, 05:56:17 am »
Yeah, keyshot leaning toward the "easy" side of things, I'd hope they would have that on be default if caustics isn't enabled.

I guess it's tricky though. Something like a stream of water should cast some shadow. But a window should not.
So maybe they should just add a checkbox saying something is a window

I had an empty coffee pot, and Boy that feature was useful. When I was using Vray, the material override was indispensable. I would love keyshot to add just a bit more in that tool. Complex materials are already time consuming to render. But in most cases, only the camera needs to see the material in a complex way. So if you're thinking something like boat paint with that heavy flakes, noise, glossy And rough reflections...Well, GI doesn't really need to see all that, and Usually reflections/refractions also. So in Vray, I'd make a simplified version of the shaders to keep the rest of the scene rendering faster. For larger renders (large being over 5k in at least one side) optimization can save an hour per image.