Object visibility not evaluating properly

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Steve Davy

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Sep 22, 2021, 6:16:45 PM9/22/21
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I'm doing a standard visibility switcharoo in a scene that works fine in playback and in the viewport.

However, on rendering with Vray sometimes objects are disappearing as they should but the visibility of their replacements is not toggling on.

When this was first happening I was driving this with an expression so thought that wasn't evaluating properly. So now I'm driving it with a condition node (so hard wired), but it's still occuring. This is with Maya 2020.

Has anyone else seen this and by chance know what's causing it? I've never had this issue before. It's possible it's an issue with the DG graph evaluation node although I haven't tested this yet.

Of course, it could be a Vray issue as well. Rendering with Vray 5.

Steve Davy

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Sep 22, 2021, 6:21:19 PM9/22/21
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*DG evaluation MODE

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Sent: Wednesday, September 22, 2021 3:16 PM
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Subject: [maya_he3d] Object visibility not evaluating properly
 
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ian zeigler

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Sep 22, 2021, 10:23:43 PM9/22/21
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Thats funny, I have been wrestling with the same issue all day.  

Yes, it works fine in viewport and playblasts then when rendering in Vray, wacky stuff was happening.

It was like 5 frames before the switch, that was bad.

I used keyed visibility, I know has always been a no-no, back in mental ray days but has usually worked in vray , ( i thought )

my fix was just turned off the animation in visibility and re-rendered 5 frames and that worked.  

i guess you could animate Vray clipping planes very quickly between the 2 models and get the effect?

good luck!



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Anthony Enos

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Sep 22, 2021, 11:18:18 PM9/22/21
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I encountered a similar bug in a couple Redshift releases. If I remember correctly, the keyframes worked when I plugged the transform’s visibility into the shape node’s visibility or directly keyed the shape node instead.

On Sep 22, 2021, at 7:23 PM, ian zeigler <i...@photonicstudio.com> wrote:



Steve Davy

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Oct 7, 2021, 4:11:25 PM10/7/21
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Unfortunately nothing seems to fix this for me. Tried all three evaluation modes, as well as the suggestion to plug transform into shape node.

Not sure without explicit testing whether this is a Maya or a Vray issue, but it's pretty problematic, and obviously should simply work. Visibility is a keyable attribute that I've used in this way countless times in the past.

The only thing I haven't tried is explicitly keying ALL vis attrs on and off instead of trying to drive them with an attribute, but that's a can of worms....


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Subject: Re: [maya_he3d] Re: Object visibility not evaluating properly
 

suraj harrington-odedra

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Oct 7, 2021, 5:25:09 PM10/7/21
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Alright. I’ll suggest something, even though it probably won’t work. 

Back in my mental ray days, I used to have similar issues when I was rendering with motion blur. Visibility samples would be taken before and after the current integer frame and so mental ray got confused. My solution was to offset my visibility keyframes by 0.5 of a frame, and set the in/out tangents to “Stepped”, so when mental ray sampled the motion blur either side of a frame, it would sample the same visibility value. 

Probs won’t help, but just in case an old man can be of use….

On 7 Oct 2021, at 21:11, Steve Davy <stevi...@hotmail.com> wrote:



Steve Davy

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Oct 7, 2021, 6:54:40 PM10/7/21
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Hmmm.... problem is this is neither for animation nor am I using any motion blur.

I'm literally talking two frames in some cases, one in state A the second in state B, with state B bits not showing up as they should.

But, thanks for making me think a bit harder about the way rendering works at a technical level 😉

I will at least try setting interpolation to stepped even if for all intents and purposes over a single frame this should mean nothing.

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suraj harrington-odedra

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Oct 7, 2021, 7:41:45 PM10/7/21
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Told you I was old and useless. 

On 7 Oct 2021, at 23:54, Steve Davy <stevi...@hotmail.com> wrote:



SEQUENZ | Gerstenmaier

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Oct 8, 2021, 4:06:12 AM10/8/21
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Keying the visibility attribute works here with no problem. So I guess your attribute is not evaluated by V-Ray correctly. We had that behavior with an attribute driven by a multiply node. 

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bobrobertuma

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Oct 8, 2021, 10:24:09 AM10/8/21
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Hahaha, If you are than so am (I, and lots of people on this list).  Your old school fix suggestion was great.

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