Using deviceOrientation to calibrate Camera

Hi,

I would like the deviceOrientation to effectively control the camera in a scene, to achieve the effect of moving around a virtual environment within the app. I specifically want the camera to be transformed in sync with the deviceOrientation, rather than transforming everything else.

To achieve this I'm attempting the following flow:

At a single time during runtime, record the current deviceOrientation as 'calibrationOrientation', and the current camera transform as 'calibrationCamera'. From then on: 1. derive a transform 'orientationUpdate' representing the difference from calibrationOrientation to the current deviceOrientation. 2. apply orientationUpdate to calibrationCamera.

I have 2 parts to this question, the first is the sanity check on my approach; am i trying to solve this in a reasonable and logical manner? the second is how do i find the 'difference' between 2 transforms.

ie.

Transform difference = Input.deviceOrientation - calibrationOrientation;

and how do i 'apply' it to the camera

ie.

Camera.current.transform = calibrationCamera + difference;

I think i probably need to obtain a matrix4x4 of the transforms and inverse one and multiply, but I'm not sure how to do this with Unity classes.

Thanks.