PostProcessingVolume priority doesnt seem to be working correctly

Development Rendering
, , ,
1

PostProcessingVolume priority doesnt seem to be working correctly.

I have multiple post processing volumes overlapping… the problem is even though i have the one i want at a higher priority number it still looks different when the other priorities are enabled vs disabled… like it literally modifies the bloom some more and other things… not quite sure what thats all about…

113776-postbug.jpg
113776-postbug.jpg833×1536 570 KB

2

Hi Kurylo3d,

I ran a test with the following steps:

  1. Open a blank project
  2. Turn off auto exposure in the project settings
  3. In the default map remove everything but the directional light and the floor
  4. Add two post process volumes make Volume 1 very large and place Volume 2 inside Volume 1
  5. Make Volume 2 have a priority of 1
  6. Make the bloom intensity 0 in the volume 2 and Bloom max intensity in Volume 1
  7. Make a new material and plug a vector 3 with a high value into emissive color so that the material glows
  8. Add a cube to the scene with the emissive material
  9. Move from Volume 1 into volume 2 so that you are inside both volumes

The Bloom behaved as expected in my test. What you might be seeing is the blend distance, if you are within this range the engine will blend in the higher priority postprocess as you get closer to it.

113786-temp.jpg
113786-temp.jpg372×574 26.7 KB

If this isn’t the case please make a test in a blank project that reproduces the issue and list the steps. You can use what I’ve done as an example. Otherwise, there are too many variables that come into play and that makes it impossible to determine the issue unless you take measures to narrow down the issue.

,

Ed

3

So far disabling auto exposure in the project settigns as well in the volumes did not help.

Blend radius also has no effect.

I just noticed that even if its 2 post process volumes with the exact same settings there is a minor change in color of the scene in the places they overlap… regaurdless of priorty…

I will try on a blank level next to see what i can break.

4

Ok when i paste the 2 post processing volumes into a brand new scene with the default sky scene… the problem still exists.

5

I was able to reproduce this problem from scratch with 2 post processing volumes… 1 post process volume having the “White Balance” Temp… increased largely for testing purposes…

Seems like white balance isnt obeying priority… it just sort of applys both layers together i guess… i dont know… not sure if any other settings have this problem… bloom seems fine in this example… bloom may have changed in the other scene simply because white balance… thats my guess… but it could be other things in the post that dont obey the priority… have not tested every thing individually.

6

That is very strange, I was unable to reproduce this issue.

By default the Blend weight for each volume is 1. If you changed the blend weight to be less than 1 that is the only way two overlapping volumes would blend regardless of priority.

Could you provide a screenshot of your postprocess settings so that I may confirm we are using the same settings in our test.

7

Its odd… i tried to recreate it… wasnt able to… then i tried to recreate it again… and i was able to… not quite sure how or why… maybe a specific order the post process volumes were created and or set to priorities?.. i dont know… but i have again been able to recreate it…

As you can see from the screenshot… there should be no temp modifying… yet it is… from the lower priority one…

114106-postbug2.jpg
114106-postbug2.jpg1928×1048 327 KB

8

Im pretty sure your right. After enabling a bunch of check marks on both volumes the issue does not seem present any longer. for the help.

9

Ah, okay so what is happening in the screenshot is you have the temp set very high in one post process and unchecked in the other.

Most people would assume that the unchecked temp means that it will use default settings. While this is kind of true what is actually happening it is ignoring the post process and using default project settings when unchecked.

The engine interprets this as only having one post process rather than two since the one with the grayed out settings is “ignored”.

This is very simple to fix just check on temp and leave the value at default. Post process volumes blend based off what settings they have enabled and that can be a little confusing.

While that explains what is happening in the screenshot that doesn’t explain what you were describing earlier. So, something else may be going on here. Would you mind trying to test and have the temp turned on for both post process volumes to see if you can get that weird blending bug.

2 Likes
10

Thank you!

For me this was the answer. I didn’t realize the volumes were additive, not absolute.

This is a GOOD thing, and a very useful programming practice.

If settings are not activated, they will not be weighted.