UE 5.1 rendering with movie render queue, tiles not loading in time

Kevin_Ring · June 28, 2023, 2:34am

Thanks for the video. I see the problem, now. It comes down to a difference in how we created the Level Sequence. I did it like this:

add-level-sequence

But you did it by right-clicking in the Content Browser and adding it there. The critical difference between these two is that my approach added the level sequence to the level, whereas yours just added it as an asset. So then this code in Cesium for Unreal’s Cesium3DTileset.cpp couldn’t find your level sequence:

github.com

CesiumGS/cesium-unreal/blob/63078ac949db20e07980fb6534e144a9e6c57694/Source/CesiumRuntime/Private/Cesium3DTileset.cpp#L572


      
                  CesiumToUnreal);
            }
          }
          
          // Called when the game starts or when spawned
          void ACesium3DTileset::BeginPlay() {
            Super::BeginPlay();
          
            this->LoadTileset();
          
            // Search for level sequence.
            for (auto sequenceActorIt = TActorIterator<ALevelSequenceActor>(GetWorld());
                 sequenceActorIt;
                 ++sequenceActorIt) {
              ALevelSequenceActor* sequenceActor = *sequenceActorIt;
          
              FScriptDelegate playMovieSequencerDelegate;
              playMovieSequencerDelegate.BindUFunction(this, FName("PlayMovieSequencer"));
              sequenceActor->GetSequencePlayer()->OnPlay.Add(playMovieSequencerDelegate);
          
              FScriptDelegate stopMovieSequencerDelegate;

And so doesn’t know it’s recording a video, and so it doesn’t switch into the “wait for tile loads before snapping the frame” mode.

Easy solution: drag your level sequence from the Content Browser into the viewport, which will add it to the level. Then the recording should behave as intended.

I’m not quite sure what we can do to fix this so that the workaround isn’t needed, but at least the workaround is fairly easy. I wrote an issue to see if we can find a proper fix:

github.com/CesiumGS/cesium-unreal

A Level Sequence that is not in the level does not wait for tile loads before snapping each frame

opened 02:32AM - 28 Jun 23 UTC

kring

bug

We have periodically received reports about Sequencer videos not rendering corre…ctly. They would be missing tiles or show the wrong LOD, despite the fact that Cesium for Unreal is supposed to be waiting for all tile loads to complete before snapping each frame. For the longest time, we didn't know why this was happening. But finally, in [this thread](https://community.cesium.com/t/ue-5-1-rendering-with-movie-render-queue-tiles-not-loading-in-time/24954) a helpful user recorded a video of themselves reproducing the problem, which allowed us to zero in on the cause. The cause is that when the Level Sequence exists only as an asset in the content browser, but does not exist in the level, then Cesium won't find it and so it won't know to switch to the mode where we wait for all tiles loads on every frame. Adding the level sequence to the level will immediately fix (or at least work around) the problem. Ideally, video rendering would work even with a Level Sequence that is not in the level. We should see if there is a way to achieve this.

Thanks for your help and patience tracking this down!

Kevin