DUst and scratches

[veljko]

there was a disscution about dust and scratches few days ago, in writting a reply to question from Tony3d i made this little "tutorial", if you can call it that.
So im posting it in hopes that someone else might find something usefull in it...


> This dust stuff, how do you create this dust on objects? Can you send me a surface example to get my going? Did you see my Tube amp?

dust and scratches you say?

the key to good scratches is to see the individual object and see what parts of the opbject are most likely to get scratched and what parts of the object are used most- thoes parts would have loos of colur and texture and scratches becouse of the handling.
the best bet are sharp ends of the object, and edges alltogether, aswell as parts that are more exposed

i can illuustarte this on a box that has a little bump on it

as you can (hopefully) see, the upper box has dust nad scratches on it, the botoom one is just colour and bumpmap-

the textures on the right are textures i used for the object-
the first texture is a specularity map- used to make the bump more shini then the rest of the object. Ive done this becouse more exposed part of the object would be more polished becouse of contacts with other objects

the second one is a colour map- ive reduced the saturation on the part of the texture that goes on the bump of the box. I guess some colour loss is to be expected becouse of the contact with other objects.

third one is a bumpmap. Ive killed all of the bumps where the bomp on the box is. The same reasone as before-

and the last map is a bumpmapa for the scratches on the edges of the box aswell as a few "accidental" scratches on the box itselfe.

Ive used the bumpmaps in the diffuse chanell to add the dirtt that would accumulate in the scratches and the bumps

-well guess thats it....
:)

[lasco]

the first texture is a specularity map- used to make the bump more shini then the rest of the object. Ive done this becouse more exposed part of the object would be more polished becouse of contacts with other objects



!!????

ahem, you're ansolutely on that point, it's the opposite that will happen.
Did you ever see that on a wood varnished table for example parts that are
oftenly in contact with objects will wear out until the varnish completely disappear ?

You might also misunderstand the sense of "polishing", this generally has not to
be applied on materials like wood (have you aver seen a "polished" piece of wood ???) but on plastic materials, metal or even glass, materials on which yes the fact of being in contact with other objects can sometimes give this result. (well in some very specific conditions).

Man, your tuto's not bad but would just need that you INVERT your specular map !!

[veljko]

dont think so,

the reasone being that i didnt go with a polished wooden surface, but with plain wood

and in that cease ( a wooden surface with no polish) the opposit reasoning aplies

i know becouse i have a string with little wooden beads on it that i play with to keep me relaxed sometimes, and the parts of the beads that i most play with are much smoother then other parts-
and smoother surfaces are by definiton more specular then rough surfaces..


anyways, if someone would like the go with a polished wooden surface, he would need to invert the specular mapa, but the technique and the idea would still be relevant...

[lasco]

and smoother surfaces are by definiton more specular then rough surfaces..


that's where you are mistaking my friend,
this is especially not true for wood !!

the wood in itself does not really "contain" any specular,
it's the varnish you apply on it that does this.

So even if during some time your wood keeps its brillance
anyway the more it will be "smoothed" the more it will mean that
the varnish is weared out… at the end you get yes a very smooth surface
(mean for example your bump channel should be flat white without any grain)
but with no brillance at all as there will be no more varnish at this place !
Then it means = specuar and reflection channels at 0

…you will see one day that you may need to apply some varnish on
your beards and that it will be first on the "parts you play the more with" :-)

SMOOTH in this case means a LOW level of bump,
not SPECULAR at a high level…

[mattclary]

Lasco, wood that has been exposed to a lot of wear will become shiny. To what degree depends a lot on what type of wood you are talking about. A very dense grained wood such as oak or ebony will polish very nicely, balsa probably won't. It's pretty easy to find wooden objects that are shiny, that have no varnish.

[lasco]

I only half agree with you mattclary.
true that it depends on the type of wood but
I think the "natural brillance" you're talking about
concerns a quite minor part of woods in general…

…and for more even when if it's the case it quite never
goes to such a level of specular (velkjo's first pic)…

well let's say it's a question of personnal experience…
This case may happpen you're right, I must say I quite often
work on wood with varnish etc. and never meet the case…

…true also I generally only use mediums or pine wood,
don't earn enough to buy oak or ebony :)