Hi Jim, all,
I'm a bit confused by the "clockwise" and "anticlockwise". You mention the
orientation of the observer but not the location/orientation of the clock.
My assumptions (not sure why) for the clock: for roll, the observer (who is
facing forward) would be facing the clock; for pitch, the observer would
look right to see the clock; and for yaw, the observer would look down to
see the clock. That works for your definitions of pitch and yaw, but is
backwards for roll.
Does "clockwise" add, in some way, another degree of freedom to the
definition? Does that degree of freedom need to be nailed down in the
definitions? Or other terms used instead? I don't have any good suggestions
other than "positive" and "negative".
Cheers,
Ethan
On Wed, Aug 29, 2018 at 9:03 AM Jim Biard <jbiard at cicsnc.org> wrote:
> Hi.
>
>
> I've finally gotten back to this topic! The definitions below call out an
> attribute named "direction" that is used to specify the direction for
> positive values of the different quantities. We may need to add a
> definition for the attribute to the Conventions. The values and meanings
> for the direction attribute are:
>
> roll: "clockwise" for positive right side up and "anticlockwise" for
> positive right side down.
> pitch: "clockwise" for positive nose up and "anticlockwise" for positive
> nose down.
> yaw: "clockwise" for positive nose right and "anticlockwise" for positive
> nose left.
> surge: "positive" for positive forward and "negative" for positive
> backward.
> sway: "positive" for positive left and "negative" for positive right.
> heave: "positive" for positive up and "negative" for positive down.
>
> And here are the standard name definitions:
>
> platform_roll: Platform is a structure or vehicle that serves as a base
> for mounting sensors. Platforms include, but are not limited to,
> satellites, aeroplanes, ships, buoys, ground stations, and masts. Roll is a
> rotation about an axis (the X axis) that is perpendicular to the local
> vertical axis (the Z axis) and is coplanar with the nominal forward motion
> direction of the platform. Roll is relative to the ?at rest? rotation of
> the platform with respect to the X axis. The ?at rest? rotation of the
> platform may change over time. The direction for positive values of roll is
> specified by an attribute named direction. The value of the direction
> attribute is "clockwise" if positive values of roll represent the right
> side of the platform rising as viewed by an observer on top of the platform
> facing forward. The value of the direction attribute is "anticlockwise" if
> positive values of roll represent the right side of the platform falling.
> The directionality of roll values is unspecified if no direction attribute
> is present.
>
> platform_pitch: Platform is a structure or vehicle that serves as a base
> for mounting sensors. Platforms include, but are not limited to,
> satellites, aeroplanes, ships, buoys, ground stations, and masts. Pitch is
> a rotation about an axis (the Y axis) that is perpendicular to both the
> local vertical axis (the Z axis) and the nominal forward motion direction
> of the platform. Pitch is relative to the ?at rest? rotation of the
> platform with respect to the Y axis. The ?at rest? rotation of the platform
> may change over time. The direction for positive values of pitch is
> specified by an attribute named direction. The value of the direction
> attribute is "clockwise" if positive values of pitch represent the front of
> the platform rising as viewed by an observer on top of the platform facing
> forward. The value of the direction attribute is "anticlockwise" if
> positive values of pitch represent the front of the platform falling. The
> directionality of pitch values is unspecified if no direction attribute is
> present.
>
> platform_yaw: Platform is a structure or vehicle that serves as a base for
> mounting sensors. Platforms include, but are not limited to, satellites,
> aeroplanes, ships, buoys, ground stations, and masts. Yaw is a rotation
> about the local vertical axis (the Z axis). Yaw is relative to the ?at
> rest? rotation of the platform with respect to the Z axis. The ?at rest?
> rotation of the platform may change over time. The direction for positive
> values of yaw is specified by an attribute named direction. The value of
> the direction attribute is "clockwise" if positive values of yaw represent
> the front of the platform moving to the right as viewed by an observer on
> top of the platform facing forward. The value of the direction attribute is
> "anticlockwise" if positive values of yaw represent the front of the
> platform moving to the left. The directionality of yaw values is
> unspecified if no direction attribute is present.
>
> platform_surge: Platform is a structure or vehicle that serves as a base
> for mounting sensors. Platforms include, but are not limited to,
> satellites, aeroplanes, ships, buoys, ground stations, and masts. Surge is
> a displacement along an axis (the X axis) that is perpendicular to the
> local vertical axis (the Z axis) and is coplanar with the nominal forward
> motion direction of the platform. Surge is relative to the ?at rest?
> position of the platform with respect to the X axis. The ?at rest? position
> of the platform may change over time. The direction for positive values of
> surge is specified by an attribute named direction. The value of the
> direction attribute is "positive" if positive values of surge represent the
> platform moving forward as viewed by an observer on top of the platform
> facing forward. The value of the direction attribute is "negative" if
> positive values of surge represent the platform moving backward. The
> directionality of surge values is unspecified if no direction attribute is
> present.
>
> platform_sway: Platform is a structure or vehicle that serves as a base
> for mounting sensors. Platforms include, but are not limited to,
> satellites, aeroplanes, ships, buoys, ground stations, and masts. Sway is a
> displacement along an axis (the Y axis) that is perpendicular to both the
> local vertical axis (the Z axis) and the nominal forward motion direction
> of the platform. Sway is relative to the ?at rest? position of the platform
> with respect to the Y axis. The ?at rest? position of the platform may
> change over time. The direction for positive values of sway is specified
> by an attribute named direction. The value of the direction attribute is
> "positive" if positive values of sway represent the platform moving left as
> viewed by an observer on top of the platform facing forward. The value of
> the direction attribute is "negative" if positive values of sway represent
> the platform moving right. The directionality of sway values is unspecified
> if no direction attribute is present.
>
> platform_heave: Platform is a structure or vehicle that serves as a base
> for mounting sensors. Platforms include, but are not limited to,
> satellites, aeroplanes, ships, buoys, ground stations, and masts. Heave is
> a displacement along the local vertical axis (the Z axis). Heave is
> relative to the ?at rest? position of the platform with respect to the Z
> axis. The ?at rest? position of the platform may change over time. The
> direction for positive values of heave is specified by an attribute named
> direction. The value of the direction attribute is "positive" if positive
> values of heave represent the platform moving up as viewed by an observer
> on top of the platform facing forward. The value of the direction attribute
> is "negative" if positive values of heave represent the platform moving
> down. The directionality of heave values is unspecified if no direction
> attribute is present.
>
> platform_course: Platform is a structure or vehicle that serves as a base
> for mounting sensors. Platforms include, but are not limited to,
> satellites, aeroplanes, ships, buoys, ground stations, and masts. Course is
> the clockwise angle with respect to North of the nominal forward motion
> direction of the platform.
>
> platform_orientation: Platform is a structure or vehicle that serves as a
> base for mounting sensors. Platforms include, but are not limited to,
> satellites, aeroplanes, ships, buoys, ground stations, and masts.
> Orientation is the clockwise angle with respect to North of the
> longitudinal (front-to-back) axis of the platform, which may be different
> than the platform course (see platform_course).
>
> platform_roll_rate: Platform is a structure or vehicle that serves as a
> base for mounting sensors. Platforms include, but are not limited to,
> satellites, aeroplanes, ships, buoys, ground stations, and masts. Roll rate
> is the rate of rotation about an axis (the X axis) that is perpendicular to
> the local vertical axis (the Z axis) and is coplanar with the nominal
> forward motion direction of the platform. Roll rate might not include
> changes in the ?at rest? rotation of the platform, which may change over
> time. The direction for positive values of roll rate is specified by an
> attribute named direction. The value of the direction attribute is
> "clockwise" if positive values of roll rate represent the right side of the
> platform rising as viewed by an observer on top of the platform facing
> forward. The value of the direction attribute is "anticlockwise" if
> positive values of roll rate represent the right side of the platform
> falling. The directionality of roll rate values is unspecified if no
> direction attribute is present.
>
> platform_pitch_rate: Platform is a structure or vehicle that serves as a
> base for mounting sensors. Platforms include, but are not limited to,
> satellites, aeroplanes, ships, buoys, ground stations, and masts. Pitch
> rate is the rate of rotation about an axis (the Y axis) that is
> perpendicular to both the local vertical axis (the Z axis) and the nominal
> forward motion direction of the platform. Pitch rate might not include
> changes in the ?at rest? rotation of the platform, which may change over
> time. The direction for positive values of pitch rate is specified by an
> attribute named direction. The value of the direction attribute is
> "clockwise" if positive values of pitch rate represent the front of the
> platform rising as viewed by an observer on top of the platform facing
> forward. The value of the direction attribute is "anticlockwise" if
> positive values of pitch rate represent the front of the platform falling.
> The directionality of pitch rate values is unspecified if no direction
> attribute is present.
>
> platform_yaw_rate: Platform is a structure or vehicle that serves as a
> base for mounting sensors. Platforms include, but are not limited to,
> satellites, aeroplanes, ships, buoys, ground stations, and masts. Yaw rate
> is the rate of rotation about the local vertical axis (the Z axis). Yaw
> rate might not include changes in the ?at rest? rotation of the platform,
> which may change over time. The direction for positive values of yaw rate
> is specified by an attribute named direction. The value of the direction
> attribute is "clockwise" if positive values of yaw rate represent the front
> of the platform moving to the right as viewed by an observer on top of the
> platform facing forward. The value of the direction attribute is
> "anticlockwise" if positive values of yaw rate represent the front of the
> platform moving to the left. The directionality of yaw rate values is
> unspecified if no direction attribute is present.
>
> platform_surge_rate: Platform is a structure or vehicle that serves as a
> base for mounting sensors. Platforms include, but are not limited to,
> satellites, aeroplanes, ships, buoys, ground stations, and masts. Surge
> rate is the rate of displacement along an axis (the X axis) that is
> perpendicular to the local vertical axis (the Z axis) and is coplanar with
> the nominal forward motion direction of the platform. Surge rate might not
> include changes in the ?at rest? position of the platform, which may change
> over time. The direction for positive values of surge rate is specified by
> an attribute named direction. The value of the direction attribute is
> "positive" if positive values of surge rate represent the platform moving
> forward as viewed by an observer on top of the platform facing forward. The
> value of the direction attribute is "negative" if positive values of surge
> rate represent the platform moving backward. The directionality of surge
> rate values is unspecified if no direction attribute is present.
>
> platform_sway_rate: Platform is a structure or vehicle that serves as a
> base for mounting sensors. Platforms include, but are not limited to,
> satellites, aeroplanes, ships, buoys, ground stations, and masts. Sway rate
> is the rate of displacement along an axis (the Y axis) that is
> perpendicular to both the local vertical axis (the Z axis) and the nominal
> forward motion direction of the platform. Sway rate might not include
> changes in the ?at rest? position of the platform, which may change over
> time. The direction for positive values of sway rate is specified by an
> attribute named direction. The value of the direction attribute is
> "positive" if positive values of sway rate represent the platform moving
> left as viewed by an observer on top of the platform facing forward. The
> value of the direction attribute is "negative" if positive values of sway
> rate represent the platform moving right. The directionality of sway rate
> values is unspecified if no direction attribute is present.
>
> platform_heave_rate: Platform is a structure or vehicle that serves as a
> base for mounting sensors. Platforms include, but are not limited to,
> satellites, aeroplanes, ships, buoys, ground stations, and masts. Heave
> rate is the rate of displacement along the local vertical axis (the Z
> axis). Heave rate might not include changes in the ?at rest? position of
> the platform, which may change over time. The direction for positive values
> of heave rate is specified by an attribute named direction. The value of
> the direction attribute is "positive" if positive values of heave rate
> represent the platform moving up as viewed by an observer on top of the
> platform facing forward. The value of the direction attribute is "negative"
> if positive values of heave rate represent the platform moving down. The
> directionality of heave rate values is unspecified if no direction
> attribute is present.
>
>
> Grace and peace,
>
>
> Jim
>
>
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