Depth of Field: BokehDOF (with Focal Distance of 0) causes FPS loss

Issue: When using BokehDOF with a Focal Distance of 0.0 (cm) and a Focal Region larger than 0.0 (cm), FPS drops massively with objects close ([Focal Region] cm away) to the camera.
Hardware: See here.
Steps to reproduce this Issue:

  1. Create a new Project (With Starter Content)
  2. Create a PostProcess Volume, make it unbound.
  3. Set Depth of Field Method to BokehDOF.
  4. Set Focal Distance to zero.
  5. Set Scale to non-zero.
  6. Set Focal Region to non-zero (distance in which you want the fps drop to happen).
  7. Fly as close as you can to the vase on the table. Or the table. Just anything in general.
  8. Experience visual lag.

I think this may be related to the near transition region trying to exist in negative depth when the Focal Region is greater than 0.

Hey Xaymar -

I will begin with my preface that the Master Branch is meant merely for testing as it is at the best of times unstable with untested fixes and new features always being added in.

Ok with that out of the way, can you let me know what the DOF settings actually were when you have the FPS drop? Also what was the Bokeh Texture used, was it the default one? Also if you could under the Help >> About Unreal Engine you should see a 7 digit number after the version number, this is the Changelist number, can you let me know what that is as well?

Thank You

Eric Ketchum

Hello Eric,

I’m aware of that fact. Unfortunately, a plugin I have relies on code/features that hasn’t been moved into the promoted/release branch yet.

The Auto-DoF uses the following settings, with all other settings being untouched:

  • Method: BokehDOF
  • Focal Distance: 0…10000
  • Focal Region: max(FocalDistance / 10000, 0.1) * 5000
  • Near Transition Region: max(FocalRegion / 8, 100)
  • Far Transition Region: max(FocalRegion / 8, 100)
  • Scale: 0.15
  • Max Bokeh Size: 15.0

I tried finding that changelist you mentioned, but it doesn’t seem to exist:

I can however tell you the exact commit I am currently using: [385e0e1c9564d986fdd82c59ff30eec9aedf700c][2]

Michael ‘Xaymar’ Dirks

Hey Xaymar -

I have been testing this issue and have been unable to reproduce your results in the current Promoted or Master Branch of the Engine. If this problem returns please let me know.

Thank You

Eric Ketchum

Issue resurfaced, I figured out how to reproduce it 100% too!

Hi Xaymar -

Thank you for updating your repro steps. I was able to reproduce it internally and have placed a bug report as UE-26808. As we investigate a solution I will keep you informed here.

Eric Ketchum