如何在Unity Skybox内部播放的360视频中找到戴着VR耳机的用户正在看的坐标？

Question

I am trying to find the gaze co-ordinates of a user wearing a HTC Vive with integrated Tobii Eyetracker. The user is viewing a 360-degree video playing inside a Unity Skybox. I am using the Tobii Pro SDK.

I have used the VREyeTracker Prefab of Tobii and am getting parameters and values in the XML file (more details below in results). How is Unity Data different from Raw Data? Since I am not able to find any document with relevant description, I am not sure if the results obtained in the XML contain the information I am looking for.

Unity Data:

GazeDirection Value="(-0.05267334, 0.01541138, 0.99848940)" Valid="True" />
<GazeOrigin Value="(-0.03057870, 0.00478235, -0.04329382)" Valid="True" />
<PupilDiameter Value="0.00168019" Valid="True" />
<GazeRayWorld Origin="(-0.40116220, 1.04663500, -0.38193990)" Direction="(0.24876200, 0.05519217, 0.96699090)" Valid="True" />

Raw Data:

<GazeDirection UnitVector="(0.05267334, 0.01541138, 0.99848940)" Validity="Valid" />
<GazeOrigin PositionInHMDCoordinates="(30.57870000, 4.78234900, -43.29382000)" Validity="Valid" />
<Pupil PupilDiameter="1.68019100" Validity="Valid" />
PupilPosition PositionInTrackingArea="(0.55140850, 0.63337760)" Validity="Valid" />

Answer 1

If you compare both data sets you can quite easily see the following relations:

• Unity Data

   <GazeDirection Value="(-0.05267334, 0.01541138, 0.99848940)" Valid="True" /> 

  is related to

  Raw Data

   <GazeDirection UnitVector="(0.05267334, 0.01541138, 0.99848940)" Validity="Valid" /> 

  but with inverted X axis

• Unity Data

   <GazeOrigin Value="(-0.03057870, 0.00478235, -0.04329382)" Valid="True" /> 

  is ralted to

  Raw Data

   <GazeOrigin PositionInHMDCoordinates="(30.57870000, 4.78234900, -43.29382000)" Validity="Valid" /> 

  but with inverted X axis and a factor 1000 (Unity measures in meters, tobii in millimeters). This name sounds like this is the origin of the gaze ray relative to the head/hmd device -> a bit (3cm) left, a bit above (1.5cm) the center of the hmd and 4cm behind the device.

• Unity Data

   <PupilDiameter Value="0.00168019" Valid="True" /> 

  is related to

  Raw Data

   <Pupil PupilDiameter="1.68019100" Validity="Valid" /> 

  again with the factor 1000

Finally

Unity Data

<GazeRayWorld Origin="(-0.40116220, 1.04663500, -0.38193990)" Direction="(0.24876200, 0.05519217, 0.96699090)" Valid="True" />

sounds like it is related to the GazeOrigin but this time not relative to the HDM but in world coordinates where Direction is the fixation vector also in world space. Meaning in world coordinates you are looking 25cm to the left, 6cm up and 1meter in front of the position (-0.40116220, 1.04663500, -0.38193990) (sounds like you were sitting or are very small ;) ) in world space.