HeadingPitchRoll

Handling GPano Heading, Pitch, and Roll values.

When reasoning about spatial transformations, it can be helpful to individually reason about each distinct coordinate reference frame. There are at least five frames relevant to understanding the GPano:Pose values.

Coordinate Reference Frames

Coordinate Frame	Up direction	Forward direction	Right direction
Real World	sky	north	east
Camera	top of camera	front lens	right side of camera
Uncorrected Image	image top	image center	image right
Viewer App	top of screen	user eye -> screen center	screen right
Corrected Image	image top	image center	image right

GPano camera pose angles

The three pose angles GPano:PoseHeadingDegrees, GPano:PosePitchDegrees, and GPano:PoseRollDegrees describe the orientation of the camera used to capture panoramic 360 image. In particular they represent the pose of the camera frame as it relates to the world frame. These three rotation values heading, pitch, and roll are directly related to the same concepts used in aviation and aerospace, where the heading (yaw), pitch, and roll describe the orientation of an aircraft in the world. These angles have the same meaning in both the aerospace and photography fields.

Camera (Ricoh Theta)	Aircraft

Coordinate Frame	Zero heading,pitch,roll	Positive camera heading (yaw) GPano:PoseHeadingDegrees	Positive camera pitch GPano:PosePitchDegrees	Positive camera roll GPano:PoseRollDegrees
Real World (never changes)	forward north right east	forward north right east	forward north right east	forward north right east
Aviation analogy	nose north wings level	nose east of north wings level	nose tilted up horizon level	nose north right wing dipped down
Camera	lens points north camera level	lens points east of north camera level	lens points above horizon	right side dipped down
Uncorrected image	north at center horizon level	north left of center, horizon level	horizon below center, horizon level	horizon rotated ccw
Viewer correction	none	move horizon right	move horizon up	rotate horizon cw
Corrected image	north at center horizon level	north at center horizon level	north at center horizon level	north at center horizon level

Coordinate Frame	Zero camera roll	Positive camera roll GPano:PoseRollDegrees
Real World (never changes)	forward north right east	forward north right east
Aviation analogy	nose north wings level	nose north right wing dipped down
Camera	lens points north camera level	right side dipped down
Uncorrected image	north at center horizon level	horizon rotated ccw
Viewer correction	none	rotate horizon cw
Corrected image	north at center horizon level	north at center horizon level