I have been using this technique to create frosted glass for as long as I can remember. The workflow is incredibly simple. Most rendering programs can generate frosted glass, but the setup can often be tricky. In the case of Kerkythea, these settings dramatically increase the rendering time. As with everything that I do, I prefer to use Photoshop because I have more control over the final outcome and I can quickly make adjustments to get the look I am going for vs. rerendering the entire scene.



The workflow can be broken down into 3 basic steps.




Above, the base image that I will be working off of.


1. Blur:


 I first copied the part of the rendering that I wanted to be frosted glass and applied the Gaussian blur filter. The glass was rendered clear, therefore everything that is seen through the glass such as columns, walls, and lights should be blurred. It’s even make sure to blur the mullions outside of the glass.

2. Lighten


To get that “Steven Holl” frosted glass look, there are some concepts to consider. The overall brightness of the surfaces should be much lighter than standard clear glass. In the video, this is where I adjust the levels and use the dodge tool to brighten the copied layer.
Also, as objects get close to the frosted glass, their shadows become darker, and less blurred. That is why I darkened the diagonal columns and shadow under the mullions in the video.

3. Sharp Mullions


The final step is to add sharp mullions over the blurred glass layer. There are a couple of ways that I could have done this, but in this video I used sketchup linework for the mullions. Another path that I could have taken would have been to select the mullions from the original rendering using the “polygonal” tool, copy them to there own layer, and then move them above the frosted glass layer.