Single-frame sequence not written

Development Rendering
, ,
1

Whenever I try to render a sequence with a length of 1 frame, the image doesn’t write into the target directory.

2

Steps to Reproduce

  • use movie render graph
  • add an additional post-process material on the renderer node (in my case pathtracer)
  • enable high precision output (this is what breaks it)
  • output to .exr
3

Hello,

Apologies for the delay. It does appear there may be a problem here with task waiting that I’m still looking into that likely requires a code fix that still needs verification. I hope to have more time to continue working on this tomorrow.

4

[mention removed]​ , can you verify that the issue is that the post process material output isn’t written but you still get the render frame output? Or do you not get any render frame output at all?

This is the graph I’ve tested with

MGC.jpg
MGC.jpg1483×535 105 KB

5

Hi, thanks for the reply. I’ve recreated your graph and can confirm that I get no render output at all.

6

When you use your original graph, is the render frame output written but not the post process material output, or are both missing?

7

Again, both are missing. I get no files written whatsoever. Does it behave the same on your side?

8

Hey Vojtech! I just tried it in 5.7, and it was writing out fine for me. Can you take a snapshot of your Global Output Settings and share it here? Just making sure this is not the problem. How are you setting the frame number to be rendered? If you want to render frame 12, setting your start and end frames both to 12 won’t work. You need to set it to start at 12 and end at 13. The start and end frames cannot be the same number. It’s not ideal, but it’s been like that forever.

9

Hi, please see the attached example scene. I recreated the issue in a clean 5.7.4 project.

exampleScene.zip(34.7 KB)

10

Hey Vojtech,

  1. I downloaded the project.
  2. Opened the Main level and NewLevelSequence.
  3. Loaded the LS into MRQ and assigned the testMRG graph
  4. Hit Render

And I get a render of frame 1001 on the hard drive. Can you find anything I’m missing in the repro that is causing me to not see what you’re seeing?

11

Sorry, should’ve been more specific. There are two Pathtracer nodes inside the graph - one that works as you describe and one that causes problems. I think I left the working one enabled by default.

image.png.png
image.png.png1253×590 74.2 KB

12

Ahh, I see. Very specifically, the bug seems to be with a 1-frame level sequence, more than 1 spatial sample, and 32-bit output. If you change any of those it will render.

We’ll have a closer look. Thanks for reporting it!

13

The fix just went into 5.8. Here is the Git link in case you build your own engine.

https://github.com/EpicGames/UnrealEngine/commit/2aa879a9e127e251fea1ad3565f5336c760fc116