Internal coordinate system used by visual odometry is as follows.

The coordinate system is centered in the center of the sphere of the spherical approximation of our multi-camera rig. The positive z-axis goes approx. through the center of the panorama image, i.e. through image coordinates [width/2, height/2]. The positive direction x-axis intersects image plane at approx. [(3/4)*width, height/2]. The positive y-axis intersects the panorama image at approx. coordinates [width/2, 0]. Our coordinate system is thus left-handed.

Visual Odometry outputs ROS Odometry message which is in standard ros coordinate system as described in the documentation. It is assumed that forward direction is in the same direction as z-axis in the internal coordinate system.

The origin of the image coordinates is at the upper left corner of the panorama image.