Re: [CF-metadata] Platform Heave

[Nan Galbraith]

Hi again -
Nice, thanks, Jim.
My only suggestion, after a very quick read-through, is that we could
put the definition of platform at the end of the variable's definition.
That makes it much easier to scan these for the right term.

Cheers - Nan
Or, maybe the definition of platform could come somewhere before the 
definition
of starboard. Anywhere but at the start, unless there's a need for it to 
be there that
I am missing.

Also, do the definitions of roll, pitch and yaw need to explicitly state 
that these are
angles, or is it enough that that's in the canonical units for these 
variables (and implied
by '"rotation about an axis")?

platform_roll_starboard_down: Roll is an angle of rotation about an axis 
that is perpendicular to
the local vertical axis and is co-planar with the nominal forward motion 
direction of a platform.
Roll is relative to the "at rest" rotation of the platform with respect 
to the axis of rotation. The "at rest"
rotation of the platform may change over time. A 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. "Starboard down" indicates that 
positive values of roll represent
the right side of the platform falling as viewed by an observer on top 
of the platform facing forward.

Thanks - Nan

Quoting Jim Biard <jbi...@cicsnc.org>:

Hi.


How about these definitions?


Jim


==================


platform_roll_starboard_down: 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 that is perpendicular to 
the local vertical 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 axis of rotation. The 
?at rest? rotation of the platform may change over time. "Starboard 
down" indicates that positive values of roll represent the right side 
of the platform falling as viewed by an observer on top of the 
platform facing forward.

platform_roll_starboard_up: 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 that is perpendicular to 
the local vertical 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 axis of rotation. The 
?at rest? rotation of the platform may change over time. "Starboard 
up" indicates that positive values of roll represent the right side 
of the platform rising as viewed by an observer on top of the 
platform facing forward.

platform_roll_rate_starboard_down: 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 that is perpendicular to the local vertical axis and is coplanar 
with the nominal forward motion direction of the platform. Roll rate 
might not include changes to the ?at rest? rotation of the platform 
with respect to the axis of rotation, which may change over time. 
"Starboard down" indicates that positive values of roll rate 
represent the right side of the platform falling as viewed by an 
observer on top of the platform facing forward.

platform_roll_rate_starboard_up: 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 that is perpendicular to the local vertical axis and is coplanar 
with the nominal forward motion direction of the platform. Roll rate 
might not include changes to the ?at rest? rotation of the platform 
with respect to the axis of rotation, which may change over time. 
"Starboard up" indicates that 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.

platform_pitch_fore_up: 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 that is perpendicular to 
both the local vertical 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 axis of rotation. The ?at rest? rotation 
of the platform may change over time. "Fore up" indicates that 
positive values of pitch represent the front of the platform rising 
as viewed by an observer on top of the platform facing forward.

platform_pitch_fore_down: 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 that is perpendicular to 
both the local vertical 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 axis of rotation. The ?at rest? rotation 
of the platform may change over time. "Fore down" indicates that 
positive values of pitch represent the front of the platform falling 
as viewed by an observer on top of the platform facing forward.

platform_pitch_rate_fore_up: 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 that is 
perpendicular to both the local vertical axis and the nominal forward 
motion direction of the platform. Pitch rate might not include 
changes to the ?at rest? rotation of the platform with respect to the 
axis of rotation, which may change over time. "Fore up" indicates 
that positive values of pitch rate represent the front of the 
platform rising as viewed by an observer on top of the platform 
facing forward.

platform_pitch_rate_fore_down: 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 that is perpendicular to both the local vertical axis and the 
nominal forward motion direction of the platform. Pitch rate might 
not include changes to the ?at rest? rotation of the platform with 
respect to the axis of rotation, which may change over time. "Fore 
down" indicates that positive values of pitch rate represent the 
front of the platform falling as viewed by an observer on top of the 
platform facing forward.

platform_yaw_fore_starboard: 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 axis of rotation. Yaw is 
relative to the ?at rest? rotation of the platform with respect to 
the axis of rotation. The ?at rest? rotation of the platform may 
change over time. "Fore starboard" indicates that 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.

platform_yaw_fore_port: 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 axis of rotation. Yaw is 
relative to the ?at rest? rotation of the platform with respect to 
the axis of rotation. The ?at rest? rotation of the platform may 
change over time. "Fore port" indicates that positive values of yaw 
represent the front of the platform moving to the left as viewed by 
an observer on top of the platform facing forward.

platform_yaw_rate_fore_starboard: 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 
axis of rotation. Yaw rate might not include changes to the ?at rest? 
rotation of the platform with respect to the axis of rotation, which 
may change over time. "Fore starboard" indicates that 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.

platform_yaw_rate_fore_port: 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 axis of 
rotation. Yaw rate might not include changes to the ?at rest? 
rotation of the platform with respect to the axis of rotation, which 
may change over time. "Fore port" indicates that positive values of 
yaw rate represent the front of the platform moving to the left as 
viewed by an observer on top of the platform facing forward.

platform_surge_fore: 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 that is 
perpendicular to the local vertical 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 axis of 
displacement. The ?at rest? position of the platform may change over 
time. "Fore" indicates that positive values of surge represent the 
platform moving forward as viewed by an observer on top of the 
platform facing forward.

platform_surge_aft: 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 that is perpendicular to the 
local vertical 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 axis of displacement. 
The ?at rest? position of the platform may change over time. "Aft" 
indicates that positive values of surge represent the platform moving 
backward as viewed by an observer on top of the platform facing forward.

platform_surge_rate_fore: 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 
that is perpendicular to the local vertical axis and is coplanar with 
the nominal forward motion direction of the platform. Surge rate 
might not include changes to the ?at rest? position of the platform 
with respect to the axis of displacement, which may change over time. 
"Fore" indicates that positive values of surge rate represent the 
platform moving forward as viewed by an observer on top of the 
platform facing forward.

platform_surge_rate_aft: 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 
that is perpendicular to the local vertical axis and is coplanar with 
the nominal forward motion direction of the platform. Surge rate 
might not include changes to the ?at rest? position of the platform 
with respect to the axis of displacement, which may change over time. 
"Aft" indicates that positive values of surge rate represent the 
platform moving backward as viewed by an observer on top of the 
platform facing forward.

platform_sway_port: 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 that is perpendicular to both 
the local vertical 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 axis of displacement. The ?at rest? 
position of the platform may change over time. "Port" indicates that 
positive values of sway represent the platform moving left as viewed 
by an observer on top of the platform facing forward.

platform_sway_starboard: 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 that is perpendicular 
to both the local vertical 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 axis of displacement. The ?at 
rest? position of the platform may change over time. "Starboard" 
indicates that positive values of sway represent the platform moving 
right as viewed by an observer on top of the platform facing forward.

platform_sway_rate_port: 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 that 
is perpendicular to both the local vertical axis and the nominal 
forward motion direction of the platform. Sway rate may not include 
changes to the ?at rest? position of the platform with respect to the 
axis of displacement, which may change over time. "Port" indicates 
that positive values of sway rate represent the platform moving left 
as viewed by an observer on top of the platform facing forward.

platform_sway_rate_starboard: 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 a displacement along an axis that is 
perpendicular to both the local vertical axis and the nominal forward 
motion direction of the platform. Sway rate may not include changes 
to the ?at rest? position of the platform with respect to the axis of 
displacement, which may change over time. "Starboard" indicates that 
positive values of sway rate represent the platform moving right as 
viewed by an observer on top of the platform facing forward.

platform_heave_up: 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. Heave is 
relative to the ?at rest? position of the platform with respect to 
the axis of displacement. The ?at rest? position of the platform may 
change over time. "Up" indicates that positive values of heave 
represent the platform moving up as viewed by an observer on top of 
the platform facing forward.

platform_heave_down: 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. 
Heave is relative to the ?at rest? position of the platform with 
respect to the axis of displacement. The ?at rest? position of the 
platform may change over time. "Down" indicates that positive values 
of heave represent the platform moving down as viewed by an observer 
on top of the platform facing forward.

platform_heave_rate_up: 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. Heave rate may not include changes to the ?at rest? 
position of the platform with respect to the axis of displacement, 
which may change over time. "Up" indicates that positive values of 
heave rate represent the platform moving up as viewed by an observer 
on top of the platform facing forward.

platform_heave_rate_down: 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. Heave rate may not include changes to the ?at rest? 
position of the platform with respect to the axis of displacement, 
which may change over time. "Down" indicates that positive values of 
heave rate represent the platform moving down as viewed by an 
observer on top of the platform facing forward.

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).


On 9/11/18 12:13 PM, Lowry, Roy K. wrote:

Dear Nan and Jim,


It was me, on my own volition, who raised concerns about the use of 
nautical terms to try and make the concepts domain-independent. 
However, 'port' is such an elegant way of saying 'left when facing 
forward' that I don't think we should resist it. Saw a nice 
definition for port  - 'The side of a platform that is on the left 
when one is facing forward.'


Cheers, Roy.


I have now retired but will continue to be active through an 
Emeritus Fellowship using this e-mail address.



------------------------------------------------------------------------ 

*From:* CF-metadata <cf-metadata-boun...@cgd.ucar.edu> on behalf of 
Jim Biard <jbi...@cicsnc.org>
*Sent:* 11 September 2018 16:37
*To:* cf-metadata@cgd.ucar.edu
*Subject:* Re: [CF-metadata] Platform Heave

Nan,

That was my concern. As I have thought about it, we can make it 
clear in the definition text. I'll generate those later this week.

Jim


On 9/11/18 10:53 AM, Nan Galbraith wrote:
I agree completely. Thanks to all for keeping at it with this topic.

 * platform_roll_starboard_down
 * platform_yaw_fore_starboard
 * platform_pitch_fore_up
 * platform_surge_fore
 * platform_sway _port
 * platform_heave_up

There was some concern expressed about using port and starboard, 
because
satellite folks don't normally use those terms. I was unable to 
figure out exactly
who raised this point, the thread is long and sometimes my mail 
client makes the
sender of each message a little obscure.

I'm assuming even satellites have a 'front' - ADCPs don't, really, 
except by some
obscure convention set by the vendors - so presumably people will 
be able to figure
out which side is which, and these terms will be OK.

- Nan


On 9/7/18 4:07 AM, Lowry, Roy K. wrote:

Good point,


So you'd prefer platform_roll_starboard_down and so on?


Cheers, Roy.


------------------------------------------------------------------------ 
*From:* John Graybeal <jbgrayb...@mindspring.com> 
<mailto:jbgrayb...@mindspring.com>
*Sent:* 07 September 2018 03:29
*Subject:* Re: [CF-metadata] Platform Heave
Sorry if I missed a point, but joining the motion to platform_ 
will be much more findable. Platform roll for example is a really 
common expression.

John

On Sep 6, 2018, at 08:22, Lowry, Roy K. <r...@bodc.ac.uk 
<mailto:r...@bodc.ac.uk> <mailto:r...@bodc.ac.uk> 
<mailto:r...@bodc.ac.uk>> wrote:

Dear Jim,


Looking good to me.


Cheers, Roy.


------------------------------------------------------------------------ 
*From:* CF-metadata <cf-metadata-boun...@cgd.ucar.edu 
<mailto:cf-metadata-boun...@cgd.ucar.edu> 
<mailto:cf-metadata-boun...@cgd.ucar.edu> 
<mailto:cf-metadata-boun...@cgd.ucar.edu>> on behalf of Jim Biard 
<jbi...@cicsnc.org <mailto:jbi...@cicsnc.org> 
<mailto:jbi...@cicsnc.org> <mailto:jbi...@cicsnc.org>>
*Sent:* 05 September 2018 17:38
*Subject:* Re: [CF-metadata] Platform Heave

Roy, Jonathan,

I expect that surge, sway, and heave may well not have any 
"alternate direction" representations in the wild, but I recall 
that we found that the same is not true of pitch, roll, and yaw.

Should we define the "canonical" set in such a fashion that the 
sign convention is explicit and wait for people to request the 
others?

I guess that would be:

  * platform_starboard_down_roll
  * platform_fore_starboard_yaw
  * platform_fore_up_pitch
  * platform_fore_surge
  * platform_port_sway
  * platform_up_heave

Is that what we want?

Grace and peace,

Jim

On 9/5/18 12:10 PM, Jonathan Gregory wrote:

Dear Roy OK, yes. I agree with that too! We should not provide 
standard names for there is no use case yet. However, it's a 
good idea for foresee how this may be done, so that a neat 
solution is readily available when the day comes. Best wishes 
and thanks Jonathan On Wed, Sep 05, 2018 at 04:07:26PM +0000, 
Lowry, Roy K. wrote:

Date: Wed, 5 Sep 2018 16:07:26 +0000 From: "Lowry, Roy K." 
<r...@bodc.ac.uk> <mailto:r...@bodc.ac.uk> 
<mailto:r...@bodc.ac.uk> <mailto:r...@bodc.ac.uk> Subject: Re: 
[CF-metadata] Platform Heave Dear Jonathan, This isn't a desire 
to mandate, it's just an attempt to prevent the creation of six 
unnecessary Standard Names for sign conventions based on my 
knowledge and researches of oceanographic data that don't 
exist. Should anybody come up with a single example of the 
opposite sign convention in heave/sway/surge from any other 
domain then the additional Standard Names will obviously need 
setting up. Anybody know of any??? It also goes without saying 
the 'normal' conventions should leave the door open - for 
example 'upward heave' leaves the door open for a future 
'downward heave'. This follows another principle of CF Standard 
Names which is that Standard Names should only set up when 
there is a demonstrable use case and not just in case a use 
case arises. Cheers, Roy. From: CF-metadata 
<cf-metadata-boun...@cgd.ucar.edu> 
<mailto:cf-metadata-boun...@cgd.ucar.edu> 
<mailto:cf-metadata-boun...@cgd.ucar.edu> 
<mailto:cf-metadata-boun...@cgd.ucar.edu> on behalf of Jonathan 
Gregory <j.m.greg...@reading.ac.uk> 
<mailto:j.m.greg...@reading.ac.uk> 
<mailto:j.m.greg...@reading.ac.uk> 
<mailto:j.m.greg...@reading.ac.uk> Sent: 05 September 2018 16:26
Subject: Re: [CF-metadata] Platform Heave Dear Jim and Roy In 
general, we want CF to be able to describe the datasets that 
users want to describe, rather than mandating particular 
choices. Projects that use CF can do that, of course, like 
CMIP6 does, which prescribes the standard_names of the 
quantities to be submitted. Best wishes Jonathan

Date: Wed, 5 Sep 2018 09:32:37 -0400 From: Jim Biard 
<jbi...@cicsnc.org> <mailto:jbi...@cicsnc.org> 
<mailto:jbi...@cicsnc.org> <mailto:jbi...@cicsnc.org> Subject: 
Re: [CF-metadata] Platform Heave
Roy, Good point! However (of course there has to be a 'but'!), 
are we OK with forcing people to modify their data to match 
our convention? Are there other situations where a standard 
name requires a certain representation? The existing datasets 
that people have mentioned are history, but they are also 
indicative of different sign conventions out there "in the 
wild". Grace and peace, Jim On 9/5/18 4:22 AM, Lowry, Roy K. 
wrote:

Dear Jim, I think maybe you're doing more work than 
necessary. I see the work falling into three parts. 1) 
Revision of the definitions of heave/heave rate that are part 
of a new Standard Name that has yet to be accepted. 2) 
Creation of new Standard Names for Ken for sway/sway rate and 
surge/surge rate 3) Upgrade to the definitions of the 
existing Standard Names for pitch, roll and yaw. How about 
hard-wiring direction conventions for cases (1) and (2) - 
heave positive up, surge positive forwards and sway to match 
Ken's data sets? As these are new Standard Names they cannot 
be out in the wild with the opposite direction convention. We 
would then need to deprecate the three existing Standard 
Names and replace them with six new ones. One other thought 
that is occupying my mind is whether the rate parameters are 
scalars or vectors? Any thoughts? Cheers, Roy. *From:* 
CF-metadata <cf-metadata-boun...@cgd.ucar.edu> 
<mailto:cf-metadata-boun...@cgd.ucar.edu> 
<mailto:cf-metadata-boun...@cgd.ucar.edu> 
<mailto:cf-metadata-boun...@cgd.ucar.edu> on behalf of Jim 
Biard <jbi...@cicsnc.org> <mailto:jbi...@cicsnc.org> 
<mailto:jbi...@cicsnc.org> <mailto:jbi...@cicsnc.org> *Sent:* 
04 September 2018 16:36 *Subject:* Re: [CF-metadata] Platform 
Heave Jonathan, Two out of three of Nan's "most intuitive" 
rotations (pitch and yaw) are clockwise rather than 
anticlockwise if the unit vectors are X-fore, Y-port, and 
Z-up, which form a right-hand coordinate system. This is part 
of why you will see examples where the unit vectors are 
defined as X-fore, Y-starboard, and Z-down. This orientation 
of the unit vectors makes yaw to starboard, pitch up, and 
roll starboard down all anticlockwise rotations, but it 
points the Z unit vector down, which is, for most people, 
rather counter-intuitive. And this is why we are trying to 
define things in terms that don't require specification of 
unit vector directions. I'm going to try to continue down 
that path and avoid calling out clockwise/anticlockwise. 
Grace and peace, Jim On 9/4/18 10:18 AM, Jonathan Gregory wrote:

Dear Jim

If that's the general consensus, then we can go that 
general direction. I'll prepare pairs of everything.

Thank you for your flexibility.

Regarding Nan's suggestions for names - I'm not a "ship 
person" so starboard and port are unfamiliar terms that I 
have to constantly check myself on. I dislike putting them 
in the names. I don't see them in regular use in the 
satellite domain. The same goes for bow as far as usage 
outside of the ship domain. Airplanes have noses. 
Satellites have ... I don't know if there is even a name, 
as there is no need for a leading edge. I'll struggle to 
find something, and then we can wrangle over it.

I agree with you - it would be better to have something 
generic and self- explanatory, even if it diverges from 
familiar terminology.

I think the "most intuitive" way to represent the angles - 
and most consistent as well, in my view - is clockwise 
rotations around the unit vectors. This makes positive yaw 
to starboard, positive pitch nose up, and positive roll 
starboard up. But we are talking about having both signs 
represented in names, so I guess that is moot.

I agree with this too. For describing polygonal bounds, we 
say that the vertices should be traversed anticlockwise as 
seen from above. That is a positive direction of rotation 
around the vertical axis, since longitude- latitude-upward 
is a right-handed coordinate system. I suppose this is the 
yaw rotation - but is that the opposite sign from yours? 
Best wishes Jonathan

On 9/3/18 12:51 PM, Jonathan Gregory wrote:

Dear Roy and Nan I agree that if there are existing names 
whose sign convention is undefined we can't 
retrospectively define it. I think those ones ought to be 
deprecated, though, in favour of new ones with signs 
indicated. Best wishes Jonathan ----- Forwarded message 
from Nan Galbraith<ngalbra...@whoi.edu> 
<mailto:ngalbra...@whoi.edu> <mailto:ngalbra...@whoi.edu> 
<mailto:ngalbra...@whoi.edu>-----

Date: Sun, 02 Sep 2018 11:57:33 -0400
From: Nan Galbraith<ngalbra...@whoi.edu> 
<mailto:ngalbra...@whoi.edu> <mailto:ngalbra...@whoi.edu> 
<mailto:ngalbra...@whoi.edu>
 I second Roy's suggestion; existing names have undefined 
directionality, and new names have explicit directions. 
This seems like the only way to move forward. If there's 
a difference of opinion on which direction should be in 
the new name, we can easily create a pair for each term. 
What would the explicit names be? Some of the terms in 
the thread below use 'right' and 'left' where 'port' and 
'starboard' might be more clear, since, as Roy points 
out, left and right can be taken as 'looking forwards 
from the platform or looking at the front of the 
platform.' I also agree that these are the most intuitive 
way to represent these angles/motions:

heave positive up pitch positive bow up yaw positive to 
starboard roll positive starboard side down

Would the names be something like heave_up, pitch_bow_up, 
yaw_to_starboard, and roll_to_starboard? We do need to 
differentiate these from the exiting names. Regards - Nan 
Quoting "Lowry, Roy K."<r...@bodc.ac.uk> 
<mailto:r...@bodc.ac.uk> <mailto:r...@bodc.ac.uk> 
<mailto:r...@bodc.ac.uk> <mailto:r...@bodc.ac.uk> 
<mailto:r...@bodc.ac.uk> <mailto:r...@bodc.ac.uk> 
<mailto:r...@bodc.ac.uk>:

Dear Jim, From my researches into existing oceanographic 
data sets (SeaDataCloud holdings plus EU glider data 
projects), covering heave, pitch, roll and yaw. I 
haven't discovered a single deviation from the conventions:
heave positive up Pitch positive bow/nose up yaw 
positive to starboard roll starboard side down I have 
yet to find any data sets, other than those described by 
Ken in these discussions, in my searches containing 
surge or sway. The only ambiguity I have found in the 
wider domain of Google is where the concept of 'positive 
clockwise' has been used without specifying whether the 
observer is looking forwards from the platform or 
looking at the front of the platform. This isn't helped 
by the multitude of bidirectional vectors (arrows at 
each end) in illustrative diagrams. Might our lives be 
made easier if we adopted a set of conventions, state 
them explicitly in the Standard Names as Jonathan 
suggests leaving room in the unlikely - in my view at 
least - event of Standard Names for the opposite 
convention being required? Cheers, Roy. From: 
CF-metadata on behalf of Jim Biard<jbi...@cicsnc.org> 
<mailto:jbi...@cicsnc.org> <mailto:jbi...@cicsnc.org> 
<mailto:jbi...@cicsnc.org>
Sent: 31 August 2018 14:38  Jonathan, That's only part 
of the issue. Here are the issues as I see them. * There 
is no single sign convention being followed in existing 
datasets "in the wild". * There is a long-standing 
convention for vertical coordinates using the attribute 
positive rather than having pairs of standard names for 
height_positive_up, height_positive_down, etc. The 
suggested solution is corollary, and the positive 
attribute could be used instead of adding a new 
attribute named direction with a suitable expansion of 
possible valid values. * In order to cover all bases, 
we'd need three versions for each standard name (e.g. - 
platform_roll, platform_roll_clockwise, 
platform_roll_anticlockwise - or similar names) * Having 
three different versions of each standard name will lead 
to new possibilities for getting things wrong by picking 
the wrong version. * Semantically, there is only one 
concept in each case. If I am searching for roll 
variables and I have multiple names that mean roll, I 
must expand my search to include all variants. This is a 
small example, but there are other examples of this 
problem that are definitely not trivial and defeat one 
of the goals for using standard names - being able to 
find like quantities across datasets, particularly using 
automated techniques rather than human eyes. Grace and 
peace, Jim On 8/31/18 8:52 AM, Jonathan Gregory wrote: 
Dear all I haven't been following this discussion, so 
please excuse me if I've missed the point. I think you 
are suggesting introducing a new attribute to indicate 
the positive sense of various new quantities for 
platform orientation - is that right? To do that would 
not be consistent with other standard names, which 
(where relevant) all have the positive sense indicate in 
the standard name itself. That's why there are many 
pairs of standard names for upward/downward, in 
particular. The reason for doing this is to make it 
impossible to name the quantity without indicating its 
sign convention, whereas a separate attribute can be 
omitted, and probably sometimes will. It also opens new 
possibilities for getting things wrong, by putting 
illegal values in it. Therefore I would argue for the 
same approach here, both because I think it's less 
error-prone, and for consistency with other CF standard 
names. I'm sure the objection occurs to you that this 
means more standard names. That's true, but it's only 
twice as many, I believe, since each of the quantities 
has only two possible senses.
Best wishes Jonathan
----- Forwarded message from Kenneth Kehoe 
<kke...@ou.edu> <mailto:kke...@ou.edu> 
<mailto:kke...@ou.edu> <mailto:kke...@ou.edu> 
<mailto:kke...@ou.edu> <mailto:kke...@ou.edu> 
<mailto:kke...@ou.edu> <mailto:kke...@ou.edu>
Date: Thu, 30 Aug 2018 12:05:44 -0600
From: Kenneth Kehoe<kke...@ou.edu> 
<mailto:kke...@ou.edu> <mailto:kke...@ou.edu> 
<mailto:kke...@ou.edu>
Subject: Re: [CF-metadata] Platform Heave
I think we should keep things simple as Ethan suggests 
below. But since the proposed attribute "direction" is 
defined as indicating the positive direction we don't 
need to include the word positive. The terms would then 
be: roll: "right_side_up" and "right_side_down" pitch: 
"nose_up" and "nose_down" yaw: "nose_right" and 
"nose_left" surge: "forward" and "backward" sway: "left" 
and "right" heave: "up" and "down" It would be nice to 
be more explicit in the netCDF file and require less on 
the standard_name definition so I would suggest we use 
the original proposed attribute name of 
"positive_direction" with the above allowed values. Or 
if we don't want to add a new attribute we could use the 
existing "positive" attribute and expand its allowed 
use. I've proposed this in the past and it was decided 
to not expand the definition. I think the concern for 
not expanding positive was the requirement of only using 
that attribute on coordinate variables. For the 
coordinate variable the only allowable values are up and 
down. But for this use those values would only be 
attached to a variable, not a coordinate variable. Since 
we are creating an attribute to define the positive 
direction I would like to add radial definition of 
"toward" and "away". But I think we can simplify this a 
bit further. If we define the point of reference that is 
moving in the standard name then we don't need to put 
the point of reference in the positive (or direction or 
positive_direction) attribute. For example the pitch 
standard_name would indicate the location of reference 
of the nose. This would then reduce the list of possible 
options to: roll: "up" and "down" pitch: "up" and "down" 
yaw: "right" and "left" surge: "forward" and "backward" 
sway: "left" and "right" heave: "up" and "down" If we 
could use the current attribute of "positive" that has 
up and down already defined then we only need to to add 
"right", "left", "forward", "backward", "toward", 
"away". Easy! Ken On 2018-8-29 13:54, Ethan Davis wrote: 
Hey Jim, How about removing one layer of terminology by 
using your definitions for the allowed values of 
"direction": roll: "positive_right_side_up" and 
"positive_right_side_down". pitch: "positive_nose_up" 
and "positive_nose_down". yaw: "positive_nose_right" and 
"positive_nose_left". surge: "positive_forward" and 
"positive_backward". sway: "positive_left" and 
"positive_right". heave: "positive_up" and 
"positive_down". Cheers, Ethan On Wed, Aug 29, 2018 at 
12:02 PM Jim Biard <jbi...@cicsnc.org 
<mailto:jbi...@cicsnc.org> <mailto:jbi...@cicsnc.org> 
<mailto:jbi...@cicsnc.org>>wrote: John, There are a 
variety of conventions for defining roll, pitch, and yaw 
out there. This is why we are avoiding a specific one. 
Others have searched existing datasets that are using 
earlier versions of these standard names (or not using 
standard names) and found that they don't all follow the 
same convention. Ethan, We purposely aren't answering 
that question directly because of the issue above. I 
believe that I have consistently followed the convention 
in which clockwise and anticlockwise are rotational 
directions around a unit vector facing the observer, 
where the X unit vector is in the nominally forward 
direction, the Z axis is in the local up direction, and 
the Y axis unit vector is "Z cross X", which forms a 
right-handed coordinate system. The terms are meaningful 
and accurate using that convention, but the names could 
be "alpha" and "beta" or "dog" and "cat" as long as they 
are used correctly. This whole topic is fraught with 
competing conventions, so we are attempting to avoid 
declaring that only one of them is valid, with it's 
corresponding requirement that everyone follow that one 
sign convention. In fact, we could reword things to 
remove naming the axes X, Y, and Z, and perhaps we 
should. I know of satellite platforms that define their 
Y axis unit vector as pointing forward and the Z axis 
unit vector as pointing down. Thoughts? Grace and peace, 
Jim On 8/29/18 1:32 PM, John Helly wrote: Perhaps one 
should refer to the discipline of hydrostatics for help 
with this? This paper, pulled from a quick search, has a 
diagram referencing the platforms' frame of reference 
with respect to its center of gravity. Sorry if this 
comment is retrograd...
J. On 8/29/18 10:09, Ethan Davis wrote: 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> <mailto: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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* Upper Ocean Processes Group            Mail Stop 29 *
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