Electron Tube Project

[Fletch]

If you look at the model I made, (download above) the glass model is given a proper thickness. It appears that your model doesn't have thickness to the glass walls of the tube. So that the refraction of the glass material is incorrect - because the model is incorrect.

[spreadcore]

If you look at the model I made, (download above) the glass model is given a proper thickness. It appears that your model doesn't have thickness to the glass walls of the tube. So that the refraction of the glass material is incorrect - because the model is incorrect.

No thickness to the glass walls? If anything I think it's too thick now.

In your model the wall thickness measures .6cm, In my "Org." model (Before I enlarged it) the wall thickness was .635cm so just about the same size.

After scaling that thickness a little more than doubled to 1.5875cm (which I was going to try to reduce if I need too or I was thinking about remaking the model to optimize it, The file size seems pretty big I figure I have too much geometry in it. So I'd fix the thickness then),

Now I left the glass refraction "IOR" setting at the default (1.52) I checked and glass runs from 1.5 to 1.7 it appears, so I assume that's okay. Though I see your example is set at 1.669

Note: I made the model from a reference image and scaled it so the glass wall thickness was a 1/4" (.635cm) since I didn't know what Thomson's actual tube wall thickness was. I had checked on CRT glass thickness, it seems it can be thicker or thinner than that, so a .635 seemed a okay starting point at least.


Thank you for your help do far.

JJ Thompson Cathode Ray Tube-sec.jpg (115.94 KiB) Viewed 3544 times

Now I used your model and made a example of what I'm doing.

cathode-ray-tube-experiment1.skp

example of What I'm doing

(266.34 KiB) Downloaded 205 times

cathode-ray-tube-experiment_Scene 2.jpg (55.32 KiB) Viewed 3544 times

[Fletch]

Rendering is an art/science.
So you will have to adjust with trial and error. If you think it's too thick - make it half as thick.

6mm thick sounds too thick at first, but maybe it's correct? A quick search finds some science glassware at 8mm thick (seems very thick to me). I just sort of threw my model together really quickly to provide a step in the right direction, I didn't measure the thickness, I just eye-balled it. If refractions are too strong, make the thickness much thinner, or reduce IOR. But initially, I suggest to try to build it accurately as possible. Guys I know like Patrick from Kerkythea forum would need to know the precise IOR for the precise glass at the precise temperature.

That's why I never really got into this type of rendering. I do arch-viz.

I guess for IOR maybe try "flint" glass? I really don't know.

[Fletch]

This material is complex and built in the Deep Editor.

[spreadcore]

This material is complex and built in the Deep Editor.

That material looks good! I had played around with using Photoshop and making some glows and using png's in models a little bit.

I rebuilt my model and since using lights with the volumetric's had issues at smaller scales, I replaced the lights with emitters to simulate the beam. Which was a little simpler and the results are okay.

I'm going to experiment with the lights and volumetric and see just what can be done with them. But for now the emitters should be okay.

This is my latest model using emitters inside, The glass came out well compared to the reference image.

Thanks for the help Fletch.

Model rebuild with emiters used

JJ Thomson CRT 002-newest_Right 005.jpg (317.93 KiB) Viewed 3357 times

For reference this is a picture of a replica of the org. 1897 electron tube.

Replica of the Org. 1897 tube.

1897 JJThomsonGasDischargeTubeElectronCavendishLab2013-08-29-17-11-41.jpg (116.49 KiB) Viewed 3357 times