Vray settings and referencing

[SonyBoy]

Not sure if this is a Maya or a Vray issue, but I'd like to see more robust consistency when using Maya's referencing system. We're doing this quite heavily where I work, referencing in files that have existing render layers, passes and quality settings already established. Since we use the same assets over and over and more often than not want more or less the same look and lighting, this approach works well for us. However, I've noticed that Vray is often pretty inconsistent with the way that it brings in its settings when used with referencing. Sometimes settings are retained, sometimes they are not. Further and worse, attributes that have been set and locked in the master file frequently come in to a referencing file with both locking and setting lost. This seems to be true whether an override has already been set or not. The most recent example of this has been sample settings on GI attributes, which for some reason bumped back down to defaults in the referencing file and resulted in an unusable render for us. Other examples include render element status toggling incorrectly, and global sampling not being retained. Obviously these can all be pretty serious if they are not noticed.

[yolov]

This has been brought up a few times before. We know that there are cases where referncing messes up with some attributes, but it's not really deterministic and we have had hard time isolating those cases.
I've put down a task to do a bit more detailed tests.
It would, however, be of great help if you could isolate specific behaviors that you know are repeatable. This would help us in distinguishing between bugs and intended behaviors and then make it easier to see what is desired and what is not.
Any help that you can provide is appreaciated.

[SonyBoy]

I'll try to provide you with more specific details as they come up. A couple of examples are the following, however. Any Vray setting that has been changed in a referencing file that is then updated in the referenced file master will not carry over. I guess this could be considered intended/desirable behavior, however unless the attr. is keyed or locked in the referencing file personally I'd prefer it didn't work this way, as frequently the whole point of referencing is to maintain settings across several different shots. Another annoyance that has come up for us is render elements that are enabled on a referenced scene's master layer will all automatically be enabled on any other render layers in a referencing scene on which they have not been explicitly turned off. This isn't transparent of course unless you check every render layer to see which RE's are enabled, and this has led to dozens of unwanted channels being included in some of our renders.

[Morbid Angel]

Yeah I guess the vray settings are handled to be disabled or ignored from reference files. But I can't see it work another way. How would vray know which settings to use? say you have 3-4 files referenced each has vray settings. Each vray settings has its own set it of attribute values. But there can only be one vray settings for the renderer. In fact I don't believe any other renderer would work like you expect either.

About the pre-setup render layers, I think I already answered that before. Its more of a maya issue, the render layer overrides just do not carry over very well in maya it self in referenced layers. I think its due to the fact that there is a node called render layer manager which records all the render layers settings. So when you have referenced layers (referenced files) you end up with multiplier render layer managers which are also handled by maya.

I think for your shots you just have to apply a slightly different log / setup then what you currently have. We do hundreds of shots of the same thing and live well with the current system,

[yolov]

Btw, Dmitry, if you recall, you've also reported a few issues about similar cases which we were completely unable to reproduce here
Which all goes to say that the referencing system is a bit inconsistent and so far we've not been able to determine how exactly.
I'm not sure about this - but I personally would not expect render settings from a referenced scene to be taken into account at all - this makes it really hard to determine where to get the render settings from in our code. Especially if you want to take some (overriden) paramaters from one node and some other paramteres from another node.
Right now the exporter only picks one single vraySettings node and expects it to be named exactly "vraySettings". Maybe some issues come from the fact that when loading the file one vraySettings from one reference gets created before the one in the master scene or the other way around sometimes and that breaks the consistency of what's observed.
I've put down a task to dedicate some time to test this a bit more thoroughly and determine what happens, how and when. Again - any help in doing so is much appreciated.

[SonyBoy]

Thanks for the feedback on this. I can tell you that *most* of the time our render settings are retained, although I've made a habit of creating overrides on the render layers in the source scene. I'm not sure if that helps or not. So far as the issue of the vraySettings node -- would this not also be the case with a full import of another scene? What happens if I import multiple assets that already have a bunch of render settings and overrides set on their render layers? Taken to its logical conclusion you seem to be saying that all render settings and overrides must be created in the final rendering scene to be sure that they stick? It also begs the question why is there a "Use from Reference" checkbox beneath the render elements window, since presumably that means that render elements from referenced files are supported. And these of course also contain render related settings....

[Morbid Angel]

yolov - yes, what happens is if you have too many nested references, like 3-4 levels of reference, then vray settings node gets confused and starts randomly selecting other vray setting nodes when you reload the scene. Quite difficult to isolate though, but importing everything solves the issue. Which brings me to next answer for SonyBoy - importing removes all the other vray settings nodes so there is only one main vray settings node (original default to your scene) which is left.
The use from reference render element check box allows vray to see render elements from reference files, but like I said before their on/off states are recorded by the render layer manager *(which is a part of maya) so that portion is handled by maya and therefore does not translate.
If you have any questions on what are the ways to handle multiple shots with single asset I'd be happy to share how we do things here.

[SonyBoy]

Just done a quick test, referencing in four assets, and it looks like all four are simply connected to the default vraySettings node in the referencing scene. I guess I'm not sure why this occurs, rather than each referenced node/layer maintaining its hardwired connections to its own vraySettings node, especially when namespaces are used, to be read as needed at render time. However, you've already mentioned this isn't the way your code works (and I'm not a coder so maybe this is unavoidable for some reason). That all said, most of the feedback here seems to be talking about the actual vraySettings node. I'm a bit unclear what this node does, rather than the Vray settings that come up when hitting the Render Settings button. It seems to be a global settings control, but I don't think I've every changed anything in here, and it's not settings in this node that I was originally asking about, rather settings such as min and max samples or threshold in the render settings window... Seems like I opened a can of worms for myself...

[Morbid Angel]

vraySettings is vray it self. Delete that node and you won't see vray globals UI its essentially what vray requires to work. Yes its a can of worms

[yolov]

Thanks for the feedback on this. I can tell you that *most* of the time our render settings are retained, although I've made a habit of creating overrides on the render layers in the source scene. I'm not sure if that helps or not. So far as the issue of the vraySettings node -- would this not also be the case with a full import of another scene? What happens if I import multiple assets that already have a bunch of render settings and overrides set on their render layers? Taken to its logical conclusion you seem to be saying that all render settings and overrides must be created in the final rendering scene to be sure that they stick? It also begs the question why is there a "Use from Reference" checkbox beneath the render elements window, since presumably that means that render elements from referenced files are supported. And these of course also contain render related settings....

"Use from reference" is for render elements only. And they exist as separate nodes in a (referenced) scene. So we can detect that they exist. The render settings live in the vraySettings node, which is expected to be either unique, or if more than one exist, then we take the one that has the exact name "vraySettings" (it has a type too, I just don't remember it right now).