Problem with animation prepass irradiance files

[jasonazure]

Apologies, for not sending any files yet!
The problem seems harder to find than I thought. It may have something to do with type/or age of processor.
I attempted to do simple batches of 5 frames on a single, quite new machine, and the error didn't occur!
I'm going to set off a tester across the render farm tomorrow, and then I will go through the irradiance files in conjunction with the render-log, looking to see if it's only occuring on certain machines.

Could it be an Embree version related issue on older machines? If so, how do I tell what version of Embree they are running......and can the version be upgraded?

[jasonazure]

OK! I am now reproducing the error!
It seems like it happens when motion-blur is switched on!
Running a batch now.......more to follow!

[jasonazure]

Yes, definitely motion-blur related!
I will package up the sample material/renders/scenes etc. now

[tashko.zashev]

Please send us all files required to reproduce the issue to our support mail. It would be helpful if you include step by step instructions on how to replicate it and the exact versions of 3DS Max and V-Ray used.

[jasonazure]

Hi Tashko,

I finally got together a video showing the error I am experiencing along with a scene file.

I sent it via WeTransfer to vraymaya@chaosgroup.com, I hope that is ok!?

[tashko.zashev]

Hi Tashko,

I finally got together a video showing the error I am experiencing along with a scene file.

I sent it via WeTransfer to vraymaya@chaosgroup.com, I hope that is ok!?

Yes, this will create a ticket in our system.

[jasonazure]

Hi Tashko,

I see that the WeTransfer file has been downloaded, but I have just realised that the ticket has probably been raised with the email address noreply@wetransfer.com, could you change it to my email address please?

Regards,

Jason

[tashko.zashev]

Thank you very much for sending us the files for this issue and especially for the video where the problem is clearly visible.
I managed to replicate it here, but I will need more time to find whether this should be reported as a bug or not.
BTW, I'm glad to hear that you have found a way to workaround it and complete your project.

Will keep you posted.

[tashko.zashev]

Hi Tashko,

I see that the WeTransfer file has been downloaded, but I have just realised that the ticket has probably been raised with the email address noreply@wetransfer.com, could you change it to my email address please?

Regards,

Jason

Yes, it is now changed.

[jasonazure]

Thank you very much for sending us the files for this issue and especially for the video where the problem is clearly visible.
I managed to replicate it here, but I will need more time to find whether this should be reported as a bug or not.
BTW, I'm glad to hear that you have found a way to workaround it and complete your project.

Will keep you posted.

Hi Tashko,

I'm a bit concerned that you aren't sure if it is a bug or not! Surely this isn't how it's supposed to work?

As I explained in my video, I worked around this problem by rendering with a batch size of one frame, which was ok when I was only loading a scene file of 120Mb. The workaround just isn't going to be acceptable on my next project where I will be loading around 4Gb each time with a loading time of several minutes! I really need to get between 5 and 10 frames per load to meet the deadline.

Regards,

Jason

[tashko.zashev]

Hello again Jason,

I did a lot of tests and can confirm that the combination of precalculated Irradiance map Animation prepass on small sequences/patches with activated camera motion blur lead to strong GI flickering. It is considered as a bug and it is already added in our bug tracker. Hope this is something quick and easy to fix.
Now I'm checking the same configuration with our V-Ray for 3DS Max plugin but haven't found any problems so far.

I see in your video you have mentioned that the object rotation is being updated every 5th frame only.
This might be a separate issue but I will wait for confirmation before sending another bug in our system.
Will keep you posed for any news.

[jasonazure]

I thought it was the fact that the 'blended' irradiance file lighting information was in the wrong place, due to it not updating the position correctly of moving objects, that was causing the flicker, especially when it blends files from the next or previous batch of files due to the big jump in object position!?

Surely this is why when I rendered one frame per batch, which meant every irradiance file had the moving objects in the correct positions, that the problem went away?

[tashko.zashev]

Excuse me for the late reply Jason.

I thought it was the fact that the 'blended' irradiance file lighting information was in the wrong place, due to it not updating the position correctly of moving objects, that was causing the flicker, especially when it blends files from the next or previous batch of files due to the big jump in object position!?

Yes, actually that's what came first in my mind when I show your video, but after some testing I found that the problem is in the method used to generate the Ir. map pre-passes. For each 5 frame sequence the moving objects are with reset position (according to the Irradiance map viewer - hope it shows the correct data for this case) when precalculate GI with V-Ray / Maya, while this works fine in V-Ray/Max. This is now considered as a bug and our dev. team will work to fix it.

As for the Irr. map animation prepass behavior with moving objects and motion blur (btw it is also presents in V-Ray for 3DS Max) where the moving objects stays at same position for the entire animation, I'm not sure whether this can be addressed as a bug or it's designed to work like that. I have sent a sample to Vlado in order to find that out.

[jasonazure]

Hi,
Just wondering if any progress has been made with this issue?

[tashko.zashev]

Hi,
Just wondering if any progress has been made with this issue?

Not yet unfortunately. We will post here when we have any news.