NormalEstimator accuracy for UBT positioning



I am currently using the structure SDK along Unity3D to build an app.
I basically want to aim with my iPad and place a pin in the world, using the UBT module to move in the scene.

For that, I use the STDepthFrame to place the point at the correct distance in the world.
Then, I use STNormalEstimator to get the normals of the real world objects, so I can rotate my point correctly (to give the impression that it is placed on a wall, ceiling, etc.)

Both these objects are correctly sent to Unity, however my normals are somewhat incorrect : I can clearly see my pin rotating as I tell it to “align” itself with the normal at the center of my screen, but it is not the correct rotation.

Is there anything I did not understand about the buffer returned by NormalEstimator ? I think there is a difference between this buffer and the coordinates of my camera space in Unity. Should i try something else than a Quaternion.LookRotation with the normal at the center of my screen ?

Thank you in advance.