Gloss map information/resources?

snow

Hey guys,

I'm looking for some information on how gloss maps actually work, and how to create decent looking ones for my renders. Can anyone give a general explanation of how they may create one/how they work. Be good to have more added to the polycount wiki section.

Thanks

cryrid

I'm guessing gloss is the same as specular exponent/ specular power, where it basically controls how wide the highlight is.

The Phong exponent defines the "tightness" of the highlight. A higher exponent results in a smaller, tighter highlight while a lower exponent results in a broader flatter one.
Different materials will exhibit highlights (tighter or broader) based upon their physical properties. A harder, smoother material such as a pool ball may have a very tight highlight while a softer, rougher material like a rubber tire may have a very broad specular highlight. In the Phong lighting equation, there is an exponent which mathematically controls the shape of the resulting highlight (tight or broad), hence the naming.

Quote/pic from http://developer.valvesoftware.com/wiki/Phong_materials

snow

Thanks Cryrid thats helped a lot.

Edit: if anyone has an example gloss map they can show me that would be great, but I understand it now.

sampson

gloss maps is kind of more material definition, for wood and concrete you would give it a very broad gloss, whereas plastic/metal you keep it tighter.

So in gloss maps i cant remember which way it is but black = tight, white = broad spec it could be the otherway around depending

jocose

I might be tottally wrong here so somone else please chime in if you know better, but its my understanding that gloss maps are just another way to simmulate the reflectivity of a surface.


This is one of the better images I have found describing this:


To be clear I DID NOT MAKE THAT IMAGE, its part of a great art tutorial you can find here:
http://www.itchstudios.com/psg/art_tut.htm#the_onion

Basically not all materials are just shiny, some of them have part of the surface that reflect things one way and another part that reflects things another way. The result is the need for two different maps: one each to describe the two different aspects of the surface.

killingpeople

jocose: That's not exactly right. That is a 2d art tutorial.
In 3d:
Specular maps define the brightness/color of a highlight.
Gloss maps define the size of a highlight.

eld

killingpeople wrote: »

jocose: That's not exactly right. That is a 2d art tutorial.
In 3d:
Specular maps define the brightness/color of a highlight.
Gloss maps define the size of a highlight.

Well, if we're only talking about using gloss without knowing how materials work, but if one wants to understand how materials and surfaces work (with specular/gloss), then that image goes a long way.

Neo_God

I'm actually quite curious as to which game engines incorporate gloss mapping. This might be irrelevant to the original poster's intent, but this is a game art forum so I thought I'd ask. I've been out of the game dev loop for awhile.

r_fletch_r

just to clarify something:
Glossyness is a measure of how much light is scattered when it bounces off a surface.
Super smooth things like polished metal/ wood/plastics have a high gloss value as they are so smooth. unfinished concrete, metal, un varnished wood have a pretty low glossyness becuase they are rough and scatter light more.
So the way to think about it really is how smooth is the material being defined.

cryrid

if anyone has an example gloss map they can show me that would be great, but I understand it now

Here's one example
http://www.adamfransson.com/armchair.html (bottom right on the texture sheet)

r_fletch_r

not knocking that example it looks great, but keep in mind that you can do a lot more with a gloss map than just flat blocks of colour. dirt/scratches/wear will all gave an effect in gloss and when included really help to sell the effect or realism

SHEPEIRO

r_fletch_r wrote: »

not knocking that example it looks great, but keep in mind that you can do a lot more with a gloss map than just flat blocks of colour. dirt/scratches/wear will all gave an effect in gloss and when included really help to sell the effect or realism

aye for starters i would generally use the spec map...then level the varius different materials gives you alot more material difference...

snow

Good feedback thanks all.