Crash when using MoveToLongitudeLatitudeHeight (UE 5.3, Cesium 2.4.1)

Hello! Sometimes I am noticing an issue and can’t figure out how to properly replicate it.

Exception raises in Runtime/Core/Public/Math/Quat.h:

	// Make sure the Rotation part of the Matrix is unit length.
	// Changed to this (same as RemoveScaling) from RotDeterminant as using two different ways of checking unit length matrix caused inconsistency. 
	if (!ensure((FMath::Abs(1.f - M.GetScaledAxis(EAxis::X).SizeSquared()) <= UE_KINDA_SMALL_NUMBER) && (FMath::Abs(1.f - M.GetScaledAxis(EAxis::Y).SizeSquared()) <= UE_KINDA_SMALL_NUMBER) && (FMath::Abs(1.f - M.GetScaledAxis(EAxis::Z).SizeSquared()) <= UE_KINDA_SMALL_NUMBER)))
		*this = TQuat<T>::Identity;

This condition raises in this code from “Math/TransformVectorized.h”:

	void SetFromMatrix(const TMatrix<T>& InMatrix)
		TMatrix<T> M = InMatrix;

		// Get the 3D scale from the matrix
		TVector<T> InScale = M.ExtractScaling();
		Scale3D = VectorLoadFloat3_W0(&InScale);

		// If there is negative scaling going on, we handle that here
		if(InMatrix.Determinant() < 0.f)
			// Assume it is along X and modify transform accordingly. 
			// It doesn't actually matter which axis we choose, the 'appearance' will be the same
			Scale3D = VectorMultiply(Scale3D, (TransformVectorRegister)GlobalVectorConstants::FloatMinus1_111 );
			M.SetAxis(0, -M.GetScaledAxis( EAxis::X ));

		TQuat<T> InRotation = TQuat<T>(M); // <=== HERE (!)
		Rotation = VectorLoadAligned(&InRotation);
		TVector<T> InTranslation = InMatrix.GetOrigin();
		Translation = VectorLoadFloat3_W0(&InTranslation);

		// Normalize rotation
		Rotation = VectorNormalizeQuaternion(Rotation);		

Just before that:

	FORCEINLINE explicit TTransform(const TMatrix<T>& InMatrix)
		SetFromMatrix(InMatrix); // <=== HERE (!)

It happens here:

void UCesiumGlobeAnchorComponent::_updateFromNativeGlobeAnchor(
    const CesiumGeospatial::GlobeAnchor& nativeAnchor) {
  this->ActorToEarthCenteredEarthFixedMatrix =
  this->_actorToECEFIsValid = true;

  // Update the Unreal relative transform
  ACesiumGeoreference* pGeoreference = this->ResolveGeoreference();
  if (IsValid(pGeoreference)) {
    glm::dmat4 anchorToLocal = nativeAnchor.getAnchorToLocalTransform(

        FTransform(VecMath::createMatrix(anchorToLocal))); // <=== HERE (!)
  } else {
    this->_lastRelativeTransformIsValid = false;

Which actually raises from here:

  // Update with the new ECEF transform, also rotating based on the new position
  // if desired.
  CesiumGeospatial::GlobeAnchor nativeAnchor =
  this->_updateFromNativeGlobeAnchor(nativeAnchor); // <=== HERE (!)

In order not to increase this topic further, I will skip some other callers.

The “main” point before exception from my code is here

 GeoComponent->MoveToLongitudeLatitudeHeight(FVector(Longitude, Latitude, Height));

GeoComponent is UCesiumGlobeAnchorComponent* and created with:

GeoComponent = CreateDefaultSubobject<UCesiumGlobeAnchorComponent>(TEXT("CesiumGlobeAnchorComponent"));

What could be the reason for this behaviour? It doesn’t happen all the time, but sometimes.

I guess this person had the same issue, but there were no answers for that:

p.s. Unreal 5.3, built from source on linux, cesium 2.4.1. Cesium is placed in Plugins inside Engine folder

Hi @sandwitch,

Thank you for including detailed information about your issue! I’m not sure what the problem could be. I understand that you can’t reliably reproduce it, but could you provide us with some more information?

  • Can you share a sample scene where you see this error? Or at least, step-by-step instructions for building the scene?
  • What else (if anything) are you doing before calling MoveToLongitudeLatitudeHeight ?
  • Does this happen on the newest version of the plugin, Cesium for Unreal v2.6.0?

Once we have this info, we can try to troubleshoot from there. Thank you!