How to texture a dirty glass(Maya software)

Arluse

Hi everyone,i am wondering how do i texture a dirty glass in maya??Is for my school homeowork...

I know how to make a glass but i dont really know how to texture it.
Can anyone tell me what should i have,like example what map should i need prepare?
And those smudges and scratches,where do i put them??Diffuse map?Transperency map?
I dont really know...
If u know the answer,hope u can answer it as simple as u can.

fatihG_

Think in layers.

Base is your clean glass. It will have its own diffuse/albedo, Specular ,gloss/roughness and transparency.
Next is your layer of dirt, what kind of dirt?
Mud? Then you want your transparency to be full opaque where the mud is on your textures and give it a shiny look if i is wet.
Dust? you probably want it to be semi transparent, more opaque than your glass, and rougher as well/less shiny, etc.
Finger prints? Probably want to keep it fairly transparent, but perhaps less glossier.

Basically figure out how each individual layer needs to be made (what are the properties of mud? properties of dust/ etc.) and then actually layer them on top of each other.

Eric Chadwick

You could put Maya in your topic title, that would attract people who know that software.
http://polycount.com/discussion/63361/information-about-polycount-new-member-introductions/p1#use

Also, what have you tried so far? It helps to post images of your attempts, screenshots of your materials, what photos you're using for reference. 
http://polycount.com/discussion/63361/information-about-polycount-new-member-introductions/p1#asking

Arluse

This is how my glass look like,the clean version(ignore the render quality)
I use mia material x,the preset is glass physical replace


This is the basic setting


I have already done my scratches texture,where do i put them?
When i put it in diffuse,i  cant see the scratches.When i lower the transperncy,i still cant my scratches.

Eric Chadwick

Thanks for the images, helps a ton!

Think about how dirt works in real life. It reduces the transparency (so you put dark gray dirt on black background, in transparency map, if black = clear). It also affects the glossiness, dirt makes the reflection less sharp more blurry (so you put dark dirt in your mostly-bright glossiness map). Dirt can also reduce the reflection if there's enough of it, think of dried mud splatters on a glossy car finish. There might also be a little bumpiness to the dirt. Etc. Glossiness will have the biggest effect though.