Projection flickers when animated

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FarbigeWelt
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Projection flickers when animated

Post by FarbigeWelt » Mon May 13, 2019 8:44 pm

Animated GIF
Projection..gif
Projection
It is an old issue. Since LuxCoreRender 2.2 beta 1 is again stable enough to render my apartment scene, I have animated the living room with its projection of a beach picture.

Unfortunately the projection flickers as it did with LuxCoreRender 2.1 and 2.0.

There are many lights spread in different rooms. One is the sinus lamp with lots of circles emitting light what leads to an over all count of 10'000 lights. One of these lights is the projecting spot which throws the picture at the wall in the animated gif above.
The number of lights might be the source of the flickering.
Interesting to know, there are always affected the same frames with every new start of animation render.
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Re: Projection flickers when animated

Post by Dade » Mon May 13, 2019 9:58 pm

Without a test scene, it is hard to have an explanation.
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Re: Projection flickers when animated

Post by FarbigeWelt » Mon May 13, 2019 10:07 pm

Dade wrote:
Mon May 13, 2019 9:58 pm
Without a test scene, it is hard to have an explanation.
I agree. The scene is rather huge. So I will crop it to a scene which I can post here and which also shows the effect. I will post it some when on Tuesdays, 15. May.
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Re: Projection flickers when animated

Post by FarbigeWelt » Tue May 14, 2019 8:37 am

Dade wrote:
Mon May 13, 2019 9:58 pm
Without a test scene, it is hard to have an explanation.
Animated GIF, it shows the flickering during the animation.
Projection-easy..gif
Projection-easy
Projection Flickers, the easy scene which shows flickers in animation.
Projection Flickers.zip
Projection Flickers
(1.48 MiB) Downloaded 23 times
I hope this helps finding a root cause.
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Piita
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Re: Projection flickers when animated

Post by Piita » Tue May 14, 2019 1:46 pm

That is really strange. I rendered a whole bunch with different settings and it appeared to affect only opencl scenes. But then I started getting the same error in cpu scenes too. I added an area light and it appears to work fine while the spot light is having trouble staying lit. Sometimes it's ok, sometimes it's dimmed and sometimes it's black.
On my end it's random. A frame that was dark can look ok on a later rendering with the same settings.
Projection Flickers.rar
(1.47 MiB) Downloaded 21 times
Attachments
projection_opencl0013.jpg
ok
projection_opencl0014.jpg
next frame the spot light is dimmed
projection_opencl0016.jpg
two frames after that the spot light is dark
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Re: Projection flickers when animated

Post by B.Y.O.B. » Tue May 14, 2019 2:07 pm

Others had this problem before, but I could never reproduce it on my end.
See e.g. this thread: viewtopic.php?f=4&t=592&start=10#p5892
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Re: Projection flickers when animated

Post by Dade » Tue May 14, 2019 4:16 pm

As usually happen, I can not reproduce this kind of "memory uninitialized" problems on Linux however I should have fixed the bug in the latest sources.
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Re: Projection flickers when animated

Post by Piita » Thu May 16, 2019 4:58 pm

I downloaded the sources today (v2.2 beta2) and used luxcoreui to render some frames that showed the problem with the version I had before (2.2 alpha1). It looks like it's fixed. Awesome work, Dade!

Edit:
It was very random on my machine. I exported the scenes from two frames and alternated rendering between the two back and forth several times. Some times a frame could be missing the spot light even though it was fine the last time. The next time I rendered the same scene it could be fine again. Weird.
If a scene was suddenly missing the spot light and I used restart (space bar) to render it again many times, it always rendered the same bug. If I then opened and rendered another scene and then again rendered the previous one which was buggy, it could render it just fine that time :)
Really weird.
OK, nobody needed to know those details, but there you go anyway :D
I did the same back and forth switching and rendering the same two scenes a lot of times with beta2 and the bug never occured.

Thanks, Dade!
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Re: Projection flickers when animated

Post by FarbigeWelt » Thu May 16, 2019 5:49 pm

Thank you all for looking into this issue.
And, Dade, thank you for fixing it although it did not show up on your Linux system.
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Re: Projection flickers when animated

Post by Dade » Thu May 16, 2019 6:45 pm

Piita wrote:
Thu May 16, 2019 4:58 pm
Edit:
It was very random on my machine.
It was related to the use of some uninitialized memory so the end result was related to the value stored there by same previous, totally unrelated, operation (i.e. very random).
Linux seems more prone to use cleared memory (i.e. initialized to 0) so this kind of problems are unlikely to show there.
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