AWS Thinkbox Discussion Forums

emission glitching

Krakatoa for 3ds Max
#1

hello,

I just upgraded my krakatoa to 2.70 and I am getting a render where the emission channel is flickering over the frames of the animation of the particles. I tried increasing the shadow map size but it did not resolve the problem. I rendering with emission turned off and the flickering went away so I know it’s coming from this channel somehow. I have a single spotlight, high angle on the particle cloud and my scene is in meters (using 3ds max 2016).

I am not sure what else I can do to debug this so if anyone out there has some suggestions that would be awesome. Thank you.

Cheers, Christian

#2

oops, sorry. My previous post was about the emission channel but it’s actually the absorption and has been all along. It’s the absorption that’s been flickering the whole time.

Cheers, Christian

#3

Here is a reference vid so you can see what I am talking about.

Cheers, Christian

#4

Hi Christian,

A few questions:

  1. Is the flicker pattern consistent (in other words, if you re-render the animation, will the glitch look identical in both versions)?
  2. Assuming the answer to 1. is yes, when you changed the Shadow Map Size of the Spot light, did it affect the flicker pattern?
  3. When you increased the Shadow Map Size, what value did you use?
  4. What Shadow Map Size value was used in the animation you posted?
  5. What happens if you switch the Spot Light to a Direct Light?

Please note that I will be travelling the coming week and my answers might be delayed.

#5

Bobo, see answers below.

  1. Is the flicker pattern consistent (in other words, if you re-render the animation, will the glitch look identical in both versions)?

NONE OF THE RENDERS I DID SHOWED TO BE CONSISTENT.

  1. Assuming the answer to 1. is yes, when you changed the Shadow Map Size of the Spot light, did it affect the flicker pattern?

NO

  1. When you increased the Shadow Map Size, what value did you use?

I INCREASED IT TO THE PRESET OF 4096

  1. What Shadow Map Size value was used in the animation you posted?

THIS WAS 1024.

  1. What happens if you switch the Spot Light to a Direct Light?

WHEN I SWITCHED THE SPOT LIGHTS I NOTICED THAT THE FLICKERS LOOKED MORE LIKE PARALLEL LINES OVER THE VOLUME, BUT IT WAS STILL FLICKERING.

I ALSO SWITCHED BACK TO KRAKATOA VERSION 2.6.1 AND RENDERED THE SAME PARTICLES BUT I STILL GOT THE FLICKERING.

I HOPE THIS IS HELPFUL. THANKS.

cheers, Christian

#6

Thanks for the answers.
Any chance you could upload somewhere the 3ds Max scene and a few frames of the PRTs involved in that segment so I can play with it and better understand what is going on?

Thank you in advance.

#7

I have had this bug happen numerous times with 10-20 million particles, magmaflow velocity->textcoord modifiers, and absorption. Weirdly enough it hasnt been happening as much lately once I switched from rendering OpenEXRs with alpha to PNGs with no alpha. That limits me a bit (extra steps) but does appear to help.

There are some old posts on this board with my attempts to work through the problem with Bobo too, may have some useful info in there.

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