Dirty steel plate

[R Reynolds]

The latest addition to my railroad needs long sheets of diamond pattern steel plate. I wanted these plates to look well used, slightly rusty and to have varying amounts of dried dirt on them. I wasn't looking forward to building the material because while it's relatively easy to build show-room new surface finishes, I had never been happy with any of my attempts at old steel and procedural dirt looked too much like soft edged clouds. I thought the only way I could get hard edged dirt would be a decal. However after much experimentation I've got a material that's more than adequate.

At this distance it's fairly convincing. The diamond pattern is a tiled normal decal.

And it almost holds up at arm's length.

The best part is that since it's procedural you can have a lot of dirt.

Or just a few random patches.

The materials (one for colours and one for textures) use a combination of native A:M and Enhance:AM combiners.  If anyone's interested, I can post a schematic of the materials showing how they work.

 

[itsjustme]

Looks fantastic, Rodger!

[Fuchur]

Great looking material – please let us know about how you did it :).

Best regarts
*Fuchur*

[R Reynolds]

As you can see, it's all based on my favorite Enhance_AM combiner; AM_Dirt. My only problem with it is the way the blend percentages work. I had assumed that if you wanted an equal distribution of six evenly distributed grey levels (0, 51, 102, 153, 204, 255) then the blends should be five bands with the same limiting percentages. A look at a histogram of the resulting material showed this wasn't true. So after some trial and error I found the blends shown that produced a reasonably even histogram and I use these consistently with colour choices that are subtly different so they combine well to my eye. Using AM_dirt, I make the basic surfaces, steel and dirt (light and dark). CellTurb is used to combine a layer of light dirt with distinct dark spots scattered throughout. I also let the dark dirt slightly bleed through the light for even more variation. AM_Bozo is the combiner used to make regions of steel and dirt. The key variable here is the Gain of 99.99% which makes the dirt have hard edges. The AM_Dirt Bump variable is cranked up for both dirts but set to 0 for steel as I preferred the look of a separate texture material not based on colour variation. 

Both the steel and dirt texture are variations of the Dented plugin from Alibi with the steel texture being small craters and the dirt texture being larger bumps. These are combined using AM_Bozo again with its variables the same as the colours so they match regions.

[Fuchur]

Amazing, thank you very much!