问题
We have a unity scene that uses arealearning which has been extremely reliable and consistent about XZ position. However we are noticing that sometimes the tango delta camera’s Y position will "jump up" very high in the scene. When we force the tango to relocalize (by covering the sensors for a few seconds), the Y position remains very off. At other times, the Y position varies a 0.5 - 1.5 unity units when we first start up our Unity app on the tango and are holding it in the exact same position in the exact same room using the same ADF file. Is there a way to get a more reliable Y position tracking and/or correct for these jumps?
回答1:
(All the XYZ coordinate is in the Unity convention in this context, x is right, y is up, z is forward)
Y position should work same as XZ coordinates, it relocalized to the height based on the ADF origin.
But note that, the ADF's origin is where you started learning(recording) ADF. Let's say you started the learning session by holding the device normally, then the ADF's origin might be a little bit higher than ground level. When you construct a virtual world to relocalize, you should take the height difference into consideration.
Another thing to check is that making sure there's no offset or original location set for DeltaPoseController prefab. DeltaPoseController will take the initial starting transformation as a offset, and add up pose on it. For example, if my DeltaPoseController's starting position is at (0,1,0), and my pose from device is (0,1,1), then the actually position for DeltaPoseController in Unity would be (0,2,1). This applies to both translation and rotation.
Another advanced (and preferred) way of defining ground level is to use the depth sensor to find out the ground height. In the Unity Augmented Reality example, it showed how to detect the plane and place a marker on it. You can easily apply the similar method to the ground plane, do a PlaneFinding and place the ground at the right height in Unity world space.
来源：https://stackoverflow.com/questions/35116122/how-to-i-get-more-reliable-y-position-tracking-for-the-google-tango-in-unity