blur behind the glass?

[JeffPatton]

It's important to list what renderer your using, because each has a different solution for this effect.

Brazil R/S = Enable glossy refraction on a Brazil glass or Brazil advanced material.
VRay = You can blur the refraction on a VRay material.
Mental Ray = glass(lume) shader has a blur transparancy option.

I've never used FinalRender, but I'd bet it can blur refractions as well.

[peakyfreak80]

Yeah, here's what the FinalRender option looks like:

[sundialsvc4]

You can also approach such a problem, probably with much more finesse and therefore control, by thinking in terms of "layers" or "passes." In other words, first you render what's behind the glass. Then, on top of that, maybe you add the blur, using a map to control how much blur occurs in what area. On top of that you overlay the frame of the building and the basic characteristics of the glass. Finally, a specular layer locks-in the reflectiveness of the glass.

When you have completed all of these, you can now "tweak" them in your compositing tool, achieving exactly the effect you want without re-rendering. Furthermore, each one of the steps that you used to generate each one of the layers is computationally simple; therefore fast.

The problem with "brute force" methods is that the computer grinds away for hours, days, or weeks ... produces a result that is not quite what you want ... and the only option is to have it grind away once again for the same amount of time with equally-uncertain results. Most projects cannot afford that. Get to know compositing and integrate it into your workflow everywhere you can. It may be the most powerful tool in your entire arsenal, because it gives you options, speed, and control.

[jedrzej]

using MENTAL RAY...and i couldn't find where this option is ...for me too many options...could you give please a short walkthrough ?...

[JeffPatton]

Sure can.

1) Start with a new Mental Ray material.
2) Add a Glass(lume) shader to the surface slot
3) Open the Glass(lume) shader and enable the Blur Transparency option (put check by On)
The spread amount controls how much the glass is blurred...the samples control how smooth the blur is.
4) To change the color of the glass you can either use the surface material, diffuse or use the "use color" in the transparancy tint section. (It defaults to use the diffuse color).

4.1) If you want transparent shadows without caustics, drag the shader you just made down to the shadow map slot of the MR material.

Hope that helps. :thumbsup:

[jedrzej]

Thank YOU!
It works....probablly i will have some q. in future..but for now ...thx....once more...

[herbert west]

For quick and dirty frosted glass:

1. Go to your glass object's properties, and set G-Buffer Object channel to 1 (or any number different than all your other objects).

2. On the top menu go to "Rendering>Effects..." and add a "Blur" effect to the list.

3. Click on "Blur" on the list and select the type of blur you want in the "Blur Type" tab that appears, then go to the "Pixel Selections" tab.

4. On the "Pixel Selections" tab, uncheck "Whole Image" and check "Object ID". Type in the ID number of your glass object then click "Add". Set "F. Radius" (feather radius) to 0 or 0.1, so the blur effect doesn't bleed.

When you render, your glass wall (or whatever object you have set at that ID) will render blurred. You can also change settings and just hit "Update Effect" at the top. This will update the blur without having to re-render your image.

[herbert west]

Or, combine Lume Glass with the blur render effect...

Here's the scene file: http://home.comcast.net/~ian_kirkley/blur_glass.zip
http://home.comcast.net/~ian_kirkley/blurglass.jpg

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