Fig. 7

Orienting tag frame to animal frame. For cetacean tagging, the orientation of the tag on the animal cannot always be finely controlled (Fig. 8A). Similar reorientation procedures that we describe can be used for tag on other animal species, where tag axes cannot be affixed to align with the animal axes. A At data displayed for a tag that is deployed on an animal with Euler rotations of 150° in the yaw direction, − 60° in the pitch direction and − 10° in the roll direction relative to animal frame. Orange boxes highlight surfacing periods, where the animal is relatively stable and averages an orientation commensurate with the navigational frame of reference (note that the animal does not have to be as still as in this example for this procedure to work). Blue box highlights a period at the start of a dive, where the whale should be rotating around the y-axis (i.e., the y-axis should remain stable in whale frame with x- and z-axes changing as their measurement of gravity changes). B Rotation matrix W_pr is constructed to mathematically rotate tag frame to the top of the whale, with z-axis ≈ − 1 g during surfacing periods. C Rotation matrix (W_y) is constructed to rotate the tag x- and y-axes to align with the whale frame such that the y-axis has minimal change during the diving maneuver as its relation to gravity should be stable. MainCATSprhTool.m accounts for all of these rotations automatically in the sub-function tagframe2whaleframe.m that is run as part of cell 8. Illustrations by Jessica Bender