Enumeration Case

ARConfiguration.WorldAlignment.gravity

The coordinate system's y-axis is parallel to gravity, and its origin is the initial position of the device.

Declaration

case gravity = 0

Discussion

The y-axis matches the direction of gravity as detected by the device's motion sensing hardware; that is, the vector (0,-1,0) points downward.

The position and orientation of the device as of when the session configuration is first run determine the rest of the coordinate system: For the z-axis, ARKit chooses a basis vector (0,0,-1) pointing in the direction the device camera faces and perpendicular to the gravity axis. ARKit chooses a x-axis based on the z- and y-axes using the right hand rule—that is, the basis vector (1,0,0) is orthogonal to the other two axes, and (for a viewer looking in the negative-z direction) points toward the right.

Figure 1

In gravity-only alignment, X and Z directions are relative to the device's initial orientation.

See Also

Alignments

case gravityAndHeading

The coordinate system's y-axis is parallel to gravity, its x- and z-axes are oriented to compass heading, and its origin is the initial position of the device.

case camera

The scene coordinate system is locked to match the orientation of the camera.