Place a custom object into viewer space using GPS coords

I am placing marker objects on a model using data taken from drone surveys. I have access to high accuracy GPS data and also omega/phi/kappa rotation data.

The goal is to move the viewer camera into position when I select a photo, so that we get a fairly good view of that part of the model from the photo.

So far, we are working with a single model and I want to verify that I'm using the transforms correctly so that this works with other models. Also, I need to match camera orientation using omega/phi/kappa, and I want to know if I also need to transform orientation data.

The model comes from Revit originally.

Here are the various transforms I have found so far using NOP_VIEWER.model.getData().

1. GlobalOffset (Vector3)
2. placementWithOffset (Matrix4) - seems to be just the inverse of GlobalOffset as a matrix?
3. placementTransform (Matrix4) - generally undefined, I've seen some hints that this is a user defined matrix.
4. refPointTransform (Matrix4)

Also, there are some transforms in the NOP_VIEWER.model.getData().metadata:

1. metadata.georeference.positionLL84 (Array[3]) - this is where the model's GPS coords are stored
2. metadata.georeference.refPointLMV (Array[3]) - no idea what this is, and it has huge and seemingly random values on many models. For example, on my current model it is [-17746143.211481072, -6429345.318822183, 27.360225423452952]
3. metadata.[custom values].angleToTrueNorth - I guess this is specifying whether the model is aligned to true or magnetic north?
4. metadata.[custom values].refPointTransform - (Array[12]) - data used to create the refPointTransform matrix above

I have been able to get the position data into viewer space using these steps:

1. Use the Autodesk.geolocation extension lonLatToLmv function to convert lon/lat/alt to viewer coords.
2. Take the converted data and apply various transforms until it is correctly positioned in model space.

const gpsPosition = new THREE.Vector3(
  longitude,
  latitude,
  altitude,
);

const position = viewer
  .getExtension('Autodesk.Geolocation')
  .lonLatToLmv(gpsPosition);

const data = viewer.model.getData();

const globalOffset = data.globalOffset;
const refPointTransform = data.refPointTransform;
const angleToTrueNorth = THREE.Math.degToRad(
    data.metadata['custom values'].angleToTrueNorth
);

// applying the transform

position.add(globalOffset)
position.applyMatrix4(refPointTransform);

// finally, rotate the position based on angle to true north. 

const quaterion = new THREE.Quaternion().setFromEuler(
  new THREE.Euler(0, 0, -angleToTrueNorth),
);

position.applyQuaternion(quaterion);

Questions:

1. do I need to apply some transforms to rotation data as well?
2. Am I applying the transforms correctly?

EDIT: figured out that the data.refPointTransform matrix already encodes the angleToTrueNorth, so I'm clearly doing something wrong in applying that twice.

I don't currently have access to the drone photo data specifying whether they are aligned to true or magnetic north, I assume it's true north though.