Strange artefarcts with temporal AA and text in motion

Development Programming & Scripting
1

Hi there,

I get very strange artefarcts when rendering text on top of a translucent material applied on a mesh which is slightly moving:

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The artefarcts disappear completely when I switch from TAA to FXAA in the global post processing volume, but everything else looks crappy without, of course.

I would really love to keep TAA active because it’s simply one of the visual highlight of UE4 and delivers nearly perfect results for most application cases.

So is it possible to eliminate this artefarcts or masking this area of the screen for TAA (and using FXAA instead)?

EDIT:

Did some experiments with the default text material:

  • Copied the default text material M_TextMaterial_Opaque_Emissive
  • Changed the blend mode to translucent or additive
  • Activated responsive AA
  • Saved material as M_TextMaterial_Translucent_Emissive_ResponsiveAA
  • Assigned to my text render component



But I cannot make the font’s brightness completely independent from the camera angle, (depending on it the font gets gray/brown instead of bright white and yellow when the angle gets to flat…).

EDIT 2:

Ok, could fix this by activating separate translucency at the background material and DEACTIVATING it on the font material.

Hmm, maybe some could explain me what just happend and WHY this works…?

Many thanks,

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Hi ,

I am not positive what caused the text to turn brown, but my guess would be sorting ambiguity with your background material you mentioned. What exactly was that material doing? It is possible that for some view angles the text was rendered first but for other view angles the background rendered first. Things like that can easily happen when one translucent object is completely inside another.

If you could also try changing the translucentsortpriority of either mesh without adjusting separate translucency that would tell us for sure. Either set your background negative or text positive and see what happens.

3

Hi Ryan,

many thanks. I will try that on monday!

EDIT: Yes, that works :slight_smile:

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Summary: If you got this problem, too:

  • Change the font material’s blend mode to translucent (and set it’s opacity to 1)
  • Activate responsive aa
  • Set the ‘translucency sort priority’ of your background mesh actor to a negative value

Many thanks, again.

Ryan: I would like to set your answer to ‘accepted’ but that’s not possible for a comment so I converted this comment a an answer.

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