Adjacent transparent materials- render or material problem?

[Speedster]

Hi all;

Posting in General Discussion because I don't know if this is a material, lighting or rendering problem.

I design medical devices, and use a lot of IV tubing and many luer connectors.  For some reason I'm having a problem with a black "surface" appearing between two clear parts- the tube and luer.  When properly bonded, the tube and luer should be all clear.  The SolidWorks model has a .002 gap between the ID of the luers and the OD of the tubes.  A workaround would have been to join the parts as one, but my client keeps changing his mind!

This issue has been posted a number of times, but no tweaks I make from previous advice seem to solve it.

Ray bounces tested at 2-6-16-32, no effect.  IOR's tweaked, ditto, depending on the material.  I've tested glass, solid glass, etc. Still there. 

I settled on a transparent custom I call PVC, and diamond for the connectors.  Amethyst for the MedRad polycarbonate on the stopcock body.  The white polypro knob was created from Translucent Wax, and is spot on.

Now- the kicker:  it only appears in a "normal" full render, but not if I do a 1200 second Realtime Render, which was my final choice for the delivered (62) renders to my client.  It looks great in the realtime window (with indirect lighting enabled) but appears only when I do a normal render.

Any clues?

Thanks!
Bill G

[JeffM]

Can you send me that model or bip? Or maybe just a cut out of just the piece showing the issue?

If so, send to support@luxion.com.

Thanks!

[Speedster]

Sure will, and thanks.  I'll make a new assembly, as this is just a tiny part of a huge medical device under an NDA.
Bill G

[Speedster]

Hi Jeff;

I emailed you (support@luxion.com) a zip with all the files on March 31st- any chance of you taking a look at them and perhaps posting some suggestions?

I took your webinar advice and applied a Realtime Gamma of 2.2, and it made a huge difference, but they still render out black, but perfect in a Realtime Render.  See -3 and -4 below, both now at gamma 2.2.

In fact, I'm revisiting this with previous projects with great result ranging from a setting of 1.8 to 2.2.  Had to rework some backplates and materials, but well worth the effort.

Thanks!
Bill G

[Speedster]

Sorry, I forgot to post image 3.
Bill G

[Robb63]

I know this is kind of like asking is the computer plugged in, but heck I might as well ask it.

Are you cranking up the bounces in the actual render quality settings, not just the "real time" tab settings?
I was only wondering that since the "Realtime"renders are working and the other isn't.

I totally agree on the gamma to 2.2 thing. I just saw the webinar that mentions that, it has made a big difference to my renderings!

[Speedster]

You caught me!  I forgot to plug the computer in!  You are right- in the render window/tab Ray Bounces were set to 6.  Kicked it to 32 (way overkill) and it rendered out just fine.  The basic deal is to sync the ray bounces.

Thank you!!! 

Jeff, you should stick this in your next webinar-

Bill G

[PhilippeV8]

It's in the manual though ..

If I e.g. want to render something with glass, I up the RB in the realtime tab untill I can't notice any difference and write down the number.  Then when I do the final rendering I set that number on the render quality tab.  As low as possible but high enough.

Works every time

[PhilippeV8]

Ah carefull though .. if I remember right, the RB in the realtime tab don't do much for final render, but the shadow does ! ... just so you know

[Speedster]

Which begs the question- why have a Ray Bounce adjustment capability in the render tab anyway?  Why would you want to change it?  It makes more sense to have it sync with Realtime, or simply not have it.  Or am I missing something?

It would seem that all image adjustments should be done in Realtime, modified in Environment and/or Materials, and the Render window be only for render settings such as output, size, etc.



Bill G