Hi guys,
I’ve drawn a little bottle filled with a red liquid. I’ve stuck a sheet in it (SHIFT-D and separate P, thus without setting any distance between the glass and the actual paper).
I’ve some questions on light and rendering and other questions on material/textures which - I know - would be better to post to the right channel, but I replicate them here, because someone among you might want to help me with them also.
If you look at the attached image, I see strange spots (yellow circles) in the liquid. Do you know why I am getting them and how to remove them?
Moreover, At the interface between the liquid and the glass there is a strange red shadow (blue arrows). Why?
I’ve rendered with 200 samples.
Clamp dir = 4
Clamp ind = 1
Reflective caustics = flagged
Refractive caustics = flagged
Filter glossy = 1
[Off-topic]
I’m trying to make this bottle real, or at least plausible. Probably, the fakest part of the bottle is the blue cap (whose material is quite unrealistic) and the irony part just below. Can you suggest me how to improve especially this part (and the whole bottle )?
Too many variables at play here…
Could be geometry or normals issues. Or your shader setup. Please upload the file for us to have a look!
Anyway, the bottle looks weird. Does it have “thickness” = an inside and an outside wall? If you want refractive objects to look plausible, you need to construct them in a physically plausible way…
Quick and dirty test with a similar bottle I had sitting on my hard drive. Not sure what you’re after: Those injection type bottles with a membrane in the lid to pierce a needle through?
Bottle has correct thickness, default glass shader. Lid is a diffuse glossy mix, driven by Fresnel.
Label also uses some glossiness - there are hardly any materials that don’t reflect light at least a little bit, so diffuse only materials tend to look odd. Also: Higher resolution for the label texture.
HDRI for the environment to provide something to reflect for the reflective surfaces.
Hi,
you did it in 10 minutes!!
Thanks for your suggestions. Actually, I did not make any thickness. I know this is wrong.
Here is my project file. Could you give a look at it?
Well, your “little” glass bottle is several meters tall… While Blender is quite size agnostic when it comes to modeling, rendering in Cycles usually works best in real-world scale. Several meters of glass react differently to light than a few millimeters.
I’m at work now, so here’s just a very quick first try in my lunch break:
Bottle scaled down to a few centimeters in height. Then I applied the scale by hitting Ctrl-A > Scale in Object mode.
After that I separated the glass part from the rest in order to add a Solidify modifier (to give the bottle walls thickness). There is a slight glitch in your bottle mesh, btw: Two edge loops so closely together that they create a visible crease in the bottle when Subsurf’ed. Tab into Edit mode, hit A to select all and then W > Remove Doubles. This will merge those doubled edge loops.
I added a studio HDRI as environment texture.
Bottle material is now a default glass shader.
In the material for the lid - I think - you confused the inputs of the Mix Shader: Whenever you mix shaders based on Fresnel or Layer Weight > Facing, the Glossy Shader needs to be connected to the BOTTOM input of the Mix Shader, not the top one.
In the aluminum material I got rid of the texture - because of its mapping it just looked wrong. Glossy colors changed to white and mid-grey respectively.
The label needs a texture with much higher resolution. In my previous post the label texture was 2048 x 2048 pixels - for comparison.
Changed camera to bigger focal length to avoid wide-angle-close-up distortions.
Just another question. You wrote: “In the material for the lid - I think - you confused the inputs of the Mix Shader: Whenever you mix shaders based on Fresnel or Layer Weight > Facing, the Glossy Shader needs to be connected to the BOTTOM input of the Mix Shader, not the top one.”.
Unfortunately, this is caused by my ignorance. I’ve never understod why connecting a shader in the upper or lower input of the Mix Shader. What’s the effect/contribution of the upper input? What’s that of the bottom input?
Looking for the file, will upload it shortly, but can’t share the HDRI file used, as it is a commercial one.
Concerning the Mix Shader node: The Fac input expects a value in the 0…1 range:
If the value is 0, solely the top input is used. If the value is 1, solely the bottom input is used. For all values 0 < x < 1 both inputs are mixed depending on the value (The closer to 0, the more of the top input and the closer to 1 the more of the bottom input.).
Now all depends on what you connect to the Fac input and what values are generated by it. Layer Weight > Facing e. g. is 0 for surfaces facing the viewer and 1 for surfaces at grazing angles. Since most materials’ glossiness increases at grazing angles, the Glossy Shader needs to be connected to the bottom input of the Mix Shader.
