Bump on glass bottle

[yesharvaishnav]

i have issue with bump map on glass bottle.

here is what I did, i selected outer polygons of bottle and gave material ID 1 and rest of the polygons material id 2. and created 3ds max multisub material in which mat id 1 has corona glass material with bump and on mat 2 , i have the same glass material but without bump but i see issue in refraction when i render it, please help.

[sprayer]

share the scene it will be faster to solve

[yesharvaishnav]

here is the test scene,

as you see you can see distinct banding of polygon where i have selected for material id. i just need bump on front surface of the cylinder, if i dont use multisub then the bump is repeated twice, i mean on front and back surface of this cylinder.

please help

[sprayer]

Yes i was struggle with this too. i think it because polygons id making object as separate without thickness what gives proper refraction.
You can use instead of polygons id just with uvw mapping in single material
https://i.imgur.com/xd4R2GM.jpg

I invert texture in photoshop not in 3ds max - this is important. and turn off tiling in texture, you can freely move uwv now without repeated textures

[yesharvaishnav]

Ya but here is the issue, if i dont use multisub yhou will get double Bump map, it will be on both side of bottle surface, i just want bump on outer surface, makes sense ?

i have attached what you did, but i get double bump

[yesharvaishnav]

what I mean is, just using bump with single material wont help, it will create double bump, how to achive the result just on front surface of glass

[sprayer]

Sorry did't see that
for that issue you may use Corona Front\back map

https://i.imgur.com/IL13VED.jpg
https://i.imgur.com/t5zxjFn.jpg

[yesharvaishnav]

woww, that worked, thanks a lot, but corona guys must resolve this issue of multisub, if you notice, even if you remove bump, as soon as you use multi sub, it cuts the refraction, so thats a bug in corona.

but your trick worked, thank you so much sir.