Allow frustrum culling on World Terrain from multiple cameras

James_Barker · June 19, 2023, 6:35am

Hello
I created two pawns, Pawn1 is a free-fly camera (primary camera) and Pawn2 is a pawn that is running around in circles.
For Pawn2, I added a top-down spring arm camera to create a projection via SceneCaptureComponent2D to create a Mini Map. I did not add any additional Camera component into Pawn2 because SceneCaptureComponent2D component seems to have its own camera. (tutorial reference I used)

Overall, it has been successful. Until noticed that while Pawn2 is doing its own independent movement, then when I move Pawn1 away, the map tiles around Pawn 2 unloads. Here are some snippets

Below is me in Pawn1 looking at where Pawn2 is. Mini map is working well as seen in top-right corner.

Below is me still in Pawn1, but looking away from Pawn2. The World Terrain map tiles unload around Pawn2. The remaining coloured ‘tile’ seen in the Mini Map is a mesh I manually added in.

Tried
Disabling frustum culling - Partially works but has a significant performance hit. Partially because the tiles render to a lower resolution which is not great.

Goal
Ultimately I want to be able allow frustrum culling of World Terrain on multiple simultaneous camera / pawn.

Is this possible? Any work around or advice would be much appreciated.

joseph.kaile · June 19, 2023, 2:41pm

Hello, it is definitely possible to have multiple cameras working. Looking at the code, the Pawn 2 must be a Player Controller for it to be recognized. There’s actually a minimap example in Cesium Unreal Samples that you can cross reference.

Kevin_Ring · June 21, 2023, 2:59am

Take a look at the logic Cesium for Unreal uses to find cameras here:

github.com

CesiumGS/cesium-unreal/blob/v1.27.1/Source/CesiumRuntime/Private/Cesium3DTileset.cpp#L1196


      
            case ETilesetSource::FromCesiumIon:
              UE_LOG(
                  LogCesium,
                  Verbose,
                  TEXT("Destroying tileset for asset ID %d done"),
                  this->IonAssetID);
              break;
            }
          }
          
          
std::vector<FCesiumCamera> ACesium3DTileset::GetCameras() const {
            TRACE_CPUPROFILER_EVENT_SCOPE(Cesium::CollectCameras)
            std::vector<FCesiumCamera> cameras = this->GetPlayerCameras();
          
          
  std::vector<FCesiumCamera> sceneCaptures = this->GetSceneCaptures();
            cameras.insert(
                cameras.end(),
                std::make_move_iterator(sceneCaptures.begin()),
                std::make_move_iterator(sceneCaptures.end()));
          
          
#if WITH_EDITOR

In short, it gets cameras associated with players, plus it gets scene capture actors (not scene capture components as you’re using, unfortunately).

So the options are:

Adapt your level to use cameras that Cesium for Unreal is able to find via this logic.
Use the functions on the CesiumCameraManager Actor to manually create and update additional cameras, using whatever (Blueprint) logic you like.
Modify Cesium for Unreal to look for and use additional cameras (such as scene capture components). We’d appreciate a PR!

Kevin