Dirt Maps

[leigh]

Dirt maps in what sense? Are you talking about grunge mapping techniques when painting textures?

[soulburn3d]

Which software? In general dirt maps are just ambient occlusion maps that are used to place dirt instead of in lighting. How simple it is to make them depends on the software. Or are you referring to a different effect?

- Neil

[flatsurface]

Sorry - should have been more specific... altho I'm not sure the extent of their uses.

This would be for application with 3DS Max 2009

In my particular case I'm referring to the black/white images called for as masks generally. I received several as part of a Total Textures collection. I'm attaching one here for reference. I'm not at my "Max" PC so I had to use one found on the web.

It looks as if they could be made easily in PS but I'm not sure if there are channels/alpha layers needed.

If there are other uses or other maps also known or called dirt maps I would like to learn about them as well.

ta

[leigh]

Oh yeah, grunge maps. Well, they're usually called grunge maps, in my experience. Those are made simply from editing photos. Generally you start by finding a nice detailed photo, removing the colour and then crunching the levels to get an extremely contrasted image. You can then use those to make grunge maps or even grunge brushes to work with.

[sundialsvc4]

I hear 'em called noise maps, too. A "map" in general is some array of data which can be used to modify some (visual) characteristic of some surface, or (as in heat-haze) the image as a whole. Different maps at different sizes, affecting different things (especially spec), are what "makes it." With a modern-day node based renderer you can affect anything you want, with anything else you want, in any way you want.

[flatsurface]

From photographs?? What would the subject matter of the photos be? Most of the dirt or grunge maps I have seen do not look like they originated as a photo - not that I doubt you - so I'm curious now as to how to select photos for this processing. :)

Thanks for any additional info.

ta

[leigh]

Any photos that have interesting details. Just play around with any that you find. Obviously ones that have contrasty details are the easiest to use, but any detailed image can be turned into a grunge map or used as a base for making grunge brushes.

[soulburn3d]

From photographs?? What would the subject matter of the photos be? Most of the dirt or grunge maps I have seen do not look like they originated as a photo - not that I doubt you - so I'm curious now as to how to select photos for this processing.

Well, find an old dumpster. Find some interesting rust patterns. Take a photo. Then bring it into photoshop. Use the magic wand to select areas that are brown (as opposed to the color the dumpster is), make a new layer, and fill that with black. Then fill the background with white. And voila. or if the color of the dumpster is way lighter than the rust or dirt, just make it grayscale, and then use the contrast or levels tools to produce an image like that. Another favorite way of mine to make dirt is to take a white sheet of paper, and rub it in actual dirt, then scan the paper. You can get some neat effects that way.

- Neil

[flatsurface]

I think I get it now - sounds like a fun project! ;)

Thanks so much for the info!

ta

[bonestructure]

I enjoy dirt/grunge maps. I rarely make a texure without them. But I'm unsure what exactly you're asking.

You have several options for doing this.

Generally, I make a nice lean texture in Photoshop, and then I add grunge and dirt by using layer blends. What I most often do is find a good photo of something dirty, like a decayed wall, add that in a new layer and then play with blending options, multiply mode, overlay, soft light, hard light, opacity percentage, experimenting with whatever looks good. If you use a black and white grunge map, the same options apply.

Or, I use a blend material. In one slot I put a basically clean material, and in the other slot I use whatever I want my dirty areas to look like, then I use a black and white grunge map as the blend mask. This is more complex than you might suspect at first, but the blend material is a truly wonderful material option. (I use Max, I can't speak for other software). I use the blend material applied on a 2500 X 2500 plane filling the window and rendered out at that size to make photo textures. Some days playing and making blended textures is all I do. It goes deeper. Each slot in the blend material can be filled with other blend materials. It can get very very complex and the tree hard to keep track of. But it's great fun.

Vray has quite a nice dirt material that I often use in the blend, though it doesn't play well with displacement, at least on my computer.

I'm a booger about grunge and dirt and such. It's extremely important. A few years ago when i was just starting to learn, Max 3 at the time, there was a very good CG guy, whose name I can't recall (sorry) who had a site on the net that I recall being called Level of Detail. His software and mine weren't the same, and he was a Mac guy and I'm a PC. But his knowledge was quite wonderful. Mostly what I was learning from his was that NOTHING is clean. Everything wears and scratches and gets dirty and stained and soiled and ages. He went through the process of making dirty textures, of having the bump maps follow those textures, of setting the specularity to follow the dirty textures. I've been insanely picky about making textures since then. And texturing is such a deep and complex subject that even after many years, I'm still working to learn and experiment and improve. I have gigs of textures I've made and collected. I'm still working to learn how to unwrap UVs well. Whatever you do, just make sure you enjoy it. Don't let it become tedious work. It can be a great deal of fun. At least it has been for me, and continues to be. Even when it's for a job, making the textures is still one of the most enjoyable parts of the process. For personal works, the textures are the first things I make, and I've taken up to a month to make textures I'm satisfied with. In fact I'm doing exactly that at the moment, have been working on textures for a week and have modeled exactly two minor objects so far, and did those two only because I needed to check the texturing lol.

Sorry for the long winded reply. Some days are just like that.

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