vase glass absorption effect problem

[jjaz82]

hi everybody.
i tried to reproduce this effect on glass vases, i don’t know if i wrong something or if i found a bug, the model is one with 3 different id, i use a corona multimap on absorpion color for give different color to the parts,

i attached the exemple
my result
and a test with ior refraction set to 1, where absorption effect result correct.

thank you

Nicola

[romullus]

It is bug (a very old one), where Corona refractive materials won’t work well if plugged into multi/sub, blend or layered materials. You should utilize material IDs together with Corona multimap in a single material - that will give you correct result.

[jjaz82]

@jjaz82

the model is one with 3 different id, i use a corona multimap on absorpion color for give different color to the parts,

hi romullus, yes i used corona multimap in a single material.

[romullus]

Oh, sorry, my mistake. Could you attach that object or at least material to inspect? I tried to put multimap in absorbtion slot and i got expected result at any IOR.

[jjaz82]

sure, thank you

vasi_vetro_23.max (360 KB)

[romullus]

Hm, i can’t replicate the issue with your scene, if i plug multimap into absorption slot, it renders just fine. See my attachment (i disabled bump and glossy refractions for more clarity, but even with those features turned on, it still renders correctly).

[jjaz82]

For me your render have same problem than mine, in the real example there aren’t al distortion i found in the render.
in render there are a gap between clear glass and colored glass, in real photo this gap dosen’t exist.

this effect is similar to when you tried to put some liquid in a glass.

[romullus]

Oh, i thought that your last picture in the first post is showing the bug, now i see what you meant. Well, it’s hard to tell how those objects in photograph are made. Maybe there are no cavities at all and those different colour areas are in fact solid infills of different glass? I haven’t seen such object in real life, so i can’t tell how that effect is made.

[jjaz82]

thank you for reply, i confirm the modeling are correct, in this photo you can see the vase have two cavity. i saw the vase i real life.

[romullus]

I see. If you plug multimap into refraction slot instead of absorbtion, then you should get much closer look to the actual photo. I guess that means that it’s a some coat on the glass instead of glass itself being colored. When you think of it, it seems logical - glass probably can’t have different absorption properties if you look at it from the other side.

[romullus]

Besides, if it would be absorbtion, then middle (solid) part would be darkest and walls would be much lighter.

[jjaz82]

@romullus

I see. If you plug multimap into refraction slot instead of absorbtion, then you should get much closer look to the actual photo. I guess that means that it’s a some coat on the glass instead of glass itself being colored. When you think of it, it seems logical - glass probably can’t have different absorption properties if you look at it from the other side.

very good reasoning, i try this way.
thank you romullus
i will post my progress

[maru]

Looks like in the original photo the vases do not have any “absorption” (the glass is clear inside the whole volume) and the insides of the cavities are painted with transparent paint. So no absorption here, just different refraction color (as I think Romullus already suggested).

[jjaz82]

after few test this is my result.
for have more control to all parts (blue glass, glass amber, glass clear) i have duplicate colored face and i gave them a thickness and set different materials.

[sprayer_1]

If you reduce\disable reflection you will see similar what you want. So reflection at glass is interfere to see color. Maybe you should try to make painted glass as deiiferent material with less reflection

http://imagizer.imageshack.com/img924/5498/2Z3mi4.jpg with less reflection and miltimap color

http://imagizer.imageshack.com/img924/6118/OaKQym.jpg with multisub but reflection is the same, don’t know why it’s so different.
I find what FOV of camera also slightly change that effect

Sometime i see strange behavior at reflection if i change glossiness to 0.99 render is very different like i change IOR at refraction.

By the way some of your reference image is cg from 3d model market so they can be fake, and some of them have visible gap

[jjaz82]

@sprayer

If you reduce\disable reflection you will see similar what you want. So reflection at glass is interfere to see color. Maybe you should try to make painted glass as deiiferent material with less reflection

http://imagizer.imageshack.com/img924/5498/2Z3mi4.jpg with less reflection and miltimap color

http://imagizer.imageshack.com/img924/6118/OaKQym.jpg with multisub but reflection is the same, don’t know why it’s so different.
I find what FOV of camera also slightly change that effect

Sometime i see strange behavior at reflection if i change glossiness to 0.99 render is very different like i change IOR at refraction.

By the way some of your reference image is cg from 3d model market so they can be fake, and some of them have visible gap
http://imagizer.imageshack.com/img921/2861/OMfqbe.jpg

yes, as I said in the previous post i separate the object in 3 parts for have more control of all these aspects, differente reflection refraction for each part i did some test and this is result.