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 <jbi...@cicsnc.org
<mailto:jbi...@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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