SetARWorldOriginLocationandRotation() Not working as expected

[bvaibhav1]

Hello,

I am on UE 4.27.2 Source Branch.

The function SetARWorldOriginLocationandRotation() does not seem to work as intended.
It has no effect on setting a different location on HoloLens Native application of Remoting. It works on iPad.

My understanding is that this should move the world with the origin to the new location, which should look as if the camera has moved in the opposite direction. This is for all unpinned/static geometry.

Kindly let me know if the understanding is correct, and if this is implemented in this manner.

Best Regards

[luis-valverde-ms]

Roping in our HoloLens platform expert @fieldsJacksonG .

[fieldsJacksonG]

This looks like missing functionality in the engine's OpenXR plugin - SetARWorldOriginLocationAndRotation sets an alignment transform in the engine, which the ARKit HMD implementation uses as an offset when returning the HMD pose. The OpenXR HMD implementation is not doing anything with this offset. I'll bring this up with Epic. Unfortunately my initial attempt to implement this in OpenXR has moved the origin, but also incorrectly moves the anchors and tracked geometries.

If you are on 5.1, you can accomplish something similar by using the UpdateExternalTrackingHMDPosition function:

The important bit from this function is the internal call to SetBaseOrientation/Position. Since you are building from source, you could expose these functions and call them directly to make this cleaner.

If you are not on 5.1, you will need to apply this commit for SetBaseOrientation/Position to work: https://github.com/EpicGames/UnrealEngine/commit/41b3de4a471a57231ea965d4d8d0bfc323f65f54