Material Colour Density Issue

[JGulliford]

Hi,
I'm having an issue with Keyshot 6 not reproducing the correct colour from the colour picker using dielectric materials. I've constructed a simple filled glass using 3 surfaces; one for the glass (outer interface), one for the content (inner interface) and another for the content top, constructed in the same way as the Jeff McCartney wine glass example.

After setting the outer glass material and the inner content interface surface with the 'correct' settings, I apply a colour to the content inside the glass, but it appears very dark and is not close to my chosen shade of colour. However if I bump the colour density up to 100, then it gets close to how I want it but I'm not sure if its exact as I do not appear to have a baseline.

I've attached some images with screenshots of material setting, the original STP file and the Keyshot file.

I have a feeling that there is a scaling issue here, as when I add a sphere inside Keyshot it appears very small. My CAD system is CATIA V5 R2013.

Id be very grateful if someone could shed a bit of light on this for me!

Thanks!
James

[Will Gibbons]

Hey JGulliford,

Your .bip file has an issue (opened as a blank scene) best off saving and sharing a .ksp file.
You're right that scale has to do with it. If you modeled this glass in mm, and you add a primitive, it'll be 1x1x1mm large.
Color density is the number of units (I'm assuming 1mm in your case) that you must penetrate into that material before the color you've chosen is represented at 100% true value.

As I understand it:
If I have a 100x100x100mm cube and I choose red and set color density at 50, then at 50mm, you'll see 100% the red I've chosen. But since the cube is 2x that value of 50, it'll be 2x as dark by the time light exits the other side of the cube.

You can reference this tutorial which suggests using liquid instead of dielectric for all materials. This gives you a transparency slider in which you can quickly dial in the color of your liquid. https://www.keyshot.com/2016/render-liquid-glass-keyshot/

Let me know if you've got further questions on this. I'll bet you can piece together a solution based on the information above.

[JGulliford]

Hey Will,
This is great, I didn't realise it worked that way, thank you very much.

I had a quick look at that tutorial and it appears I have the correct geometry, just not the correct materials. I'll give that a go.

Thanks again,
James

[JGulliford]

Hey, would you be able to explain the difference between colour density in the dielectric material and transparency in liquid material, as both settings seem to produce the same results, or do they operate in the same way?

I need to set the transparency to 100 to get the liquid close to the colour I need, is this correct. Also to answer your above question, you're correct, I have modelled the 3D in millimetres.

Thanks,
James

[guest84672]

It is the same thing. The "Liquid" material is same as the "Dielectric" material with a bunch of parameters turned off.

[JGulliford]

Ok, great. Thanks!

[DMerz III]

Also, check your global illumination setting as well as  your ray bounces, two things that are usually turned low/off. They might not be affecting the "density" in this case, but your glass looks relatively "dark" as well, which seems to be a ray bounce too low issue.