Archive for the ‘glass’ Category

Today I’m discussing using bump maps for reflections in glass. I usually see glass reflections in 3D having perfect reflections. You never really see this in reality though. There is always some bend and distortion in the glass. There are others that do use a bump map to have the reflection act more realistic. Often though, a noise map is used in the bump slot, and I haven’t seen this done properly.

In reality each pane of glass has air pressure on it, forcing it to bow in or out. The frames or mullions keep the edges in place though. There is nothing wrong with using a noise map for the bump, it’s how it’s distributed throughout the glass between the glass frames. Often I see the same noise map passing from one pane of glass to another. That is incorrect.

The trick to getting the same map on every face is using the UVW modifier on your glass and selecting Face for the Mapping type.
Today’s write-up is simple. Just glass. MR makes it very easy to create realistic glass with the A&D shader. I start with a fresh A&D shader, and all I change is the reflection to 1.0 and the refraction to 1.0….that’s it! Here’s what it looks like:

Color in the refraction is a light green

Note that to get glass to work like the image above, the glass must be a solid (there’s a thickness to the glass). If you were to render the same glass above onto a thin plane this is what it would look like:

Notice that the refraction color gets lost

Obviously this image is incorrect and defies much of physics. The question is how do you create glass with a plane? You have to change the Advanced Transparency Options from “Solid” to “Thin-walled”. Now when the thin plane renders it looks like this:

This is a great solution for thin planes, but the only way to achieve truly realistic glass is by giving it a thickness (think about the shell modifier).

I probably should have titled this Image Maps in 3D, but I’m demonstrating one particular example of frosted glass. Before I get into this example, I do want to explain image maps.

All images are the same in 3D. They have different intensity values in different locations across the image. It’s all about intensity. Once you understand this concept in any 3d software program, you can master materials. Essentially 3ds max reads black as being 0% and white being 100%. Everything grey is in between depending on how grey they are. This works for any slot in your material that allows a map to be read for it’s value. By default they have numerical values, but that will apply to the entire material. If there is a pattern that you want the values to follow…well that’s when you use an image map.

If this image were plugged into the opacity slot, then it would be an opacity map. All of the black areas would be 0% opaque, and all of the white areas would be 100% opaque. If it were plugged into the reflection slot then it would be a reflection map, and all of the black areas would be 0% reflective and all of the white areas would be….you get the idea.

In this example for frosted glass, I had to ask “what is it that makes the glass look frosted?” The major difference between frosted glass and regular glass is that you can’t see through frosted glass like you can regular. Why can’t you see through the frosted glass if it’s made out of the same material? That’s because light scatters differently. In the A&D material, refraction is what controls the transparency, and glossiness is what controls how refraction is scattered. So that’s where I plugged my map into.

Sometimes you can plug the map in straight. But in this case to get the most control of your colors, I used a Mix map, then plugged my image into the mix amount. This way I can make sure that the only intensity values used for glossiness will be white and black.

If you created your image map, and screwed up by reversing the black and whites, this is also a good way to switch the blacks with the whites.

So now my whites have a glossiness of 1.0 (pure refraction), and black has a glossiness of 0.0 (no refraction), and it gives me that frosted glass look!