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2 "frosted glass" questions

TurnerTurner Posts: 116
edited December 1969 in Carrara Discussion

Hey all,

Hope your holidays are going great!

Anyway... trying to figure out 2 things.

1) How do I make frosted glass? I have been experimenting by altering bump mapping with noise/scale, but not really getting something I like. (This includes adjusting SSS) Looking for a way to set up a realistic and, if possible, "processor-economical" ;) way to do this.

2) Why is light through material, when caustics are enabled, actually -brighter- than the area receiving direct light?

cheers
Andrew

Comments

  • DUDUDUDU Posts: 1,945
    edited December 1969

    There are several manners of reproducing freezing, here is one…
    http://mhdproductions.be/Carrarators/Verre.car

    Verre_gelé.jpg
    640 x 480 - 20K
  • TurnerTurner Posts: 116
    edited December 1969

    Thanks for the note!

    I'm looking to recreate an even, "sandblasted" surface:

    frosted_glass_whiteboard1326793281.jpg
    1280 x 960 - 73K
  • DUDUDUDU Posts: 1,945
    edited December 1969

    I'm trying since one hour... not easy !

  • TurnerTurner Posts: 116
    edited December 1969

    That's what I'm saying! :)

    Still working on it... I think a good result will be tied to using noise in the bump channel...

  • DUDUDUDU Posts: 1,945
    edited December 1969

    The difficulty is not surface but to have the blur of the objects behind…

  • WendyLuvsCatzWendyLuvsCatz Posts: 38,228
    edited December 1969

    would an anisotrophic shader do it?
    there are a few in the presets that could be a starting point.
    I reckon this might end up being one of those threads everyone has a go in, only on my android or I would ;-P
    bet Holly has some ideas and those inagoni or Digital carvers guild plugins can do it!

  • TurnerTurner Posts: 116
    edited December 1969

    Hi all -

    DUDU, I'm trying to get the blur of the objects by manipulating the surface!

    Wendy, I'm not sure but I think anisotropic may end up with directional artifacts...

    So far I'm to the point where it just looks like a shower door... getting closer...

  • TurnerTurner Posts: 116
    edited December 2013

    Here's where I'm at.

    I am trying to figure out how to both reduce the scale of the bump map as well as increase its amplitude. Not sure if that will work, but that's what I'm working towards...

    I'd also like to find out how to adjust so that the material is not "creating light"...

    diffusion.jpg
    640 x 480 - 65K
    Post edited by Turner on
  • DUDUDUDU Posts: 1,945
    edited December 1969

    It is successful very well!
    For a “sandblasted” glass, there is only one side which is sanded and the thickness of the pane is very thin!

  • evilproducerevilproducer Posts: 9,050
    edited December 1969

    Turner said:
    Here's where I'm at.

    I am trying to figure out how to both reduce the scale of the bump map as well as increase its amplitude. Not sure if that will work, but that's what I'm working towards...

    I'd also like to find out how to adjust so that the material is not "creating light"...

    Caustics don't create light, it simulates the effect light has going through objects with refraction, such as water and glass. It can magnify the effect. Like Indirect Light and the Skylight, you'll have better results if you turn off the scene's ambient light as that is also factored. Also, if the light effect is still to bright, turn down the Caustic's brightness.

  • briandaz_3e696c2bd8briandaz_3e696c2bd8 Posts: 0
    edited December 2013

    Turner said:
    ...
    I'd also like to find out how to adjust so that the material is not "creating light"...
    ...

    The trick for not creating light is to make sure your Color, Reflection, Transparancy, and Translucency add up to something LESS than 100%, or at least start there before adjusting things. In particular, Transparency and Translucency should not exceed 100% combined, and Color and Transparency should not exceed 100% combined. You can get away with more in the Reflection channel, especially if you enable fresnel effects.

    Here's a sample:
    Color: black
    Bump: Cellular scale 3% amplitude 200%
    Reflection: 17%
    Transparency: 72%
    Refraction: Crown glass
    Translucency: 20%

    The difference between #1 and #2 is the bump amplitude.
    #3 has caustics turned on. (and I moved the light)

    Edit: Also I turned Antialiasing to Best, which should improve the blurring effect of the bump channel.
    Also, I think Cellular makes a better bump than noise does for this purpose. The math works better when the renderer needs to determine the slope in a particular spot.

    ground_glass-caustics.jpg
    640 x 480 - 30K
    ground_glass-bump_200pct.jpg
    640 x 480 - 33K
    ground_glass.jpg
    640 x 480 - 31K
    Post edited by briandaz_3e696c2bd8 on
  • briandaz_3e696c2bd8briandaz_3e696c2bd8 Posts: 0
    edited December 2013

    Also, for creating a more even surface, it may help if you render an extra large image and then resize it down to what you need. The resize will average out some of the random dots to even out the look.
    Also this is the sort of scene where Lux or some other "unbiased" render engine would shine. It even has a "rough glass" shader that does exactly the sort of surface texture you're looking for without using the bump channel at all.
    There is a Lux plugin for Carrara described in other threads.

    Lux sample:

    ground_glass-lux.jpg
    800 x 600 - 37K
    Post edited by briandaz_3e696c2bd8 on
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