Request for Modification for the UCD list v1.4 - from May 2017 to Feb 2018

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This page is proposed in the new process for UCDs update discussed at the Interop meeting in Shanghai in May 2017. The new Note Maintenance for UCD specification mentions the details of the updating process. When a new UCD term seems necessary to include in the UCD list, a record describing the request for addition can be expressed as followed : new term proposed, rationale, example of usage, etc , as show in the list below.

The term is then discussed within the maintenance committee and the semantics working group and answers from the maintenance committee is given within 1 month.

Every 6 months the list of proposed changes are examined by the TCG and the validated changes are ingested in the new version of Endorsed Note for the UCD1+ list of terms.

Proposals from Solar and Planetary community ( B. Cecconi et al.)

#concept : electric current density
family: plasma environment
proposal: phys.flux ; phys.charge
requires : phys.charge with definition : Electric charge and tag : Q

##answer we understood the need for two concepts : electric current density and electric charge proposal for update:

add Q | phys.electCharge | Electric charge
add Q | phys.current | Electric current
add Q | phys.current.density | Electric current density

inserted

benefits : introduces phys.current; this definition is more focused on the requested concept --> implies better assignment

#concept family: Observation geometry ; Illumination conditions

Representation of the various angles : Explained in paper https://doi.org/10.1016/j.pss.2015.06.004

See figure attached here
theta_i = Incidence Angle, theta_e = Emergence Angle, alpha = Phase Angle
The angle phi (azimuth) is not required for illumination condition description (and we already have a UCD for this) from Baptiste Cecconi

#rationale -from B. Cecconi - 06 July 2017 - see semantics list for the email threads

In planetary sciences ... our use cases are the following:

- in EPNcore, the illumination conditions are search parameters, we have 6 separate columns for the min/max values of those 3 angles.

- for planetary images or spectra, the product metadata must contain the observation geometry, and those 3 angles are to be there, altogether.

#concept: Incidence angle
proposal: pos.incidenceAng
requires :
definition : Incidence angle
tag : Q

##answer proposed : pos.posAng.incidence with definition : "Angle of incidence of a vector e.g illumination vector"

There is a debate about this ( S.Erard): incidence and emergence are physical angles of an optical ray on an interface / can be like pos.phaseAng; then it could logically be hooked under pos directly , as pos.phaseAng

##agreed: Q pos.incidenceAng : incidence angle of optical ray on an interface

#concept: Emergence angle
proposal: pos.emergenceAng
definition : Emergence angle
tag : Q

##agreed: Q pos.emergenceAng : emergence angle of optical ray on an interface

(see discussion for incidence angle)

#concept:Azimuth angle

proposal: pos.azimuthAng

definition : Azimuthal angle
tag : Q

#answer : azimuthal angle is already defined in the ucd tree by :

pos.az.azi exists but implies an alt-azimuthal ccordinate system.

## agreed Q pos.azimuth : azimuthal angle in a generic reference plane

#concept: Cylindrical coordinates

proposal: pos.cylindrical
family : SSIG coordinates systems
rationale: no such coordinate branch in the UCD tree yet
definition : Cylindrical coordinates
tag : S

##answer accepted S pos.cylindrical "Related to cylindrical coordinates"

proposal: pos.cylindrical.r
requires :pos.cylindrical
definition : Cylindrical coordinate (radial distance from z-axis)
tag : Q

##answer accepted as pos.cylindrical.r "Radial distance from z-axis (cylindrical coordinates)"

proposal: pos.cylindrical.th
definition : Cylindrical coordinate (Azimuthal angle around z-axis)
tag : Q

##answer The conventions for the name of the angles varies : seehttp://mathworld.wolfram.com/CylindricalCoordinates.html

##answer accepted as pos.cylindrical.azi "Azimuthal angle around z-axis (cylindrical coordinates)"

proposal: pos.cylindrical.z

definition : Cylindrical coordinate (height from reference plane)
tag : Q

##answer accepted as pos.cylindrical.z "Height or altitude from reference plane (cylindrical coordinates)"

## less ambiguous as for angle names

#concept Spherical Coordinates

proposal: pos.spherical
Rationale: not present in UCD tree definition : spherical coordinates
tag : S

##answer accepted pos.spherical "Related to cylindrical coordinates"

proposal: pos.spherical.r
definition : spherical coordinate (radial distance from origin)
tag : Q

## answer accepted as pos.spherical.r "Radial distance or radius (spherical coordinates)"

proposal: pos.spherical.th
definition : spherical coordinate (colatitude angle)
tag : Q

##answer same as for cylindrical : various angle names depending on definitions ( http://mathworld.wolfram.com/SphericalCoordinates.html )

##answer proposed as pos.spherical.colat "Polar or Colatitude angle (spherical coordinates)"

proposal: pos.spherical.ph
definition : spherical coordinate (Azimuth angle)
tag : Q

##answer proposed as pos.spherical.azi " Azimuthal angle (spherical coordinates)"

#concept : orbital parameters
%Comment perifocal "src.orbital.periastron" exists but is slightly different
%Comment periapsis : check variation in meaning
proposal: src.orbital.periapsis
definition : minimal distance to the center of mass for an orbit
tag : P

##discussion postponed (time to go to lunch)

#concept : rotation params for 3D parameters

##answer

##pos. is the right branch to hook these rotation concepts
_##pos.wcs exist for 2D transformation ; pos.rotation will handle the 3D case --> propose pos.rotation3d_
##theses parameters will be used soon with real data . We decide to delay the addition and will consider several examples

proposal: pos.rotation
definition : Relative to rotation
tag : S
proposal: pos.rotation.eulerAngle
definition : Euler angles vector
tag : V
proposal: pos.rotation.quaternion
definition : rotation quaternion vector
tag : V
proposal: pos.rotation.matrix
definition : rotation matrix
tag : V
proposal: pos.rotation.axis
definition : rotation axis vector
tag : V

#concept: spatial resolution

rationale: linear resolution on cartesian or linear spatial axis as opposed to angular resolution
proposal: pos.resolution
definition : Spatial linear resolution (not angular)
tag : Q

##answer add Q | pos.resolution | Spatial linear resolution (not angular)
##inserted

#concept:heliocentric coordinates
longitude and latitude can be expressed as
proposal: pos.bodyrc.lon;pos.heliocentric
proposal: pos.bodyrc.lat;pos.heliocentric
% induced changes in assign tool: if heliocentric, or centric except geocentric , --> not earth .... change token

##answer agreed to modify assigning tool - done

##discussion: In body-centric coordinates, longitudes are defined from sub-observer point, while body-graphic coordinates are defined from a standard body reference frame

VESPA team to check consistency between heliocentric and planetocentric definitions

##answer add S | pos.bodycentric | Body-centric related coordinate <br/> ##answer add S | pos.bodygraphic | Body-graphic related coordinate

##inserted

%metadata branch

#concept: checksum
proposal: meta.checksum
rationale: to check integrity of data
definition : numerical signature of digital data
tag : Q

##answer add Q | meta.checksum | Numerical signature of digital data <br/>##inserted

proposal: time.update
definition : modification date for a dataset
##answer : use time.processing
done : add update in the definition of this ucd

# spectroscopic measures

#concept : radiance
ask for modification of the definition in the UCD list : should be radiant power from the source per unit area (of source) and unit solid angle

#concept : reflectance

proposal: phys.reflectance
rationale : different from albedo
definition: the radiance divided by solar flux : I over F

usage : radiance factor, (received radiance divided by input radiance) , may include thermal emission
% annotation master : to check ; consequence : change definition to albedo and remove reflectance
% | phys.albedo | Albedo or reflectance
derived usage : Radiance Factor : arith.factor;phys.reflectance

##answer add Q | phys.reflectance | Radiance factor, (received radiance divided by input radiance), may include thermal emission

proposal: phys.reflectance.bidirectional
definition : bidirectional reflectance
tag : Q

##answer add Q | phys.reflectance.bidirectional | Bidirectional reflectance

proposal: phys.brdf
rationale : specific term as much as psf for the community
definition : bidirectional reflectance distribution function
tag: Q

##discussion: check if phys.reflectance.bidirectional;instr.det.psf would do ?

##answer add Q | phys.reflectance.bidirectional.df | Bidirectional reflectance distribution function

proposal: phys.reflectance.factor
definition : reflectance normalized per direction cosine of incidence angle ??
tag : Q

##answer add Q | phys.reflectance.factor | Reflectance normalized per direction cosine of incidence angle

nb : check relevance and possible ambiguity with radiance factor...

%for normalized reflectance concept
proposal arith.ratio;phys.reflectance
definition : reflectance normalized per reflectance at one wavelength

#shape of planetary objects
%this is used to represent the 3D shape of object: a 3D lattice

proposal: phys.shape
definition : 3D shape of an object
tag : Q
usage : phys.shape;meta.modelled for a 3D shape model
usage : phys.shape;pos.bodyrc.alt for elevation or terrain model (distribution of altitude on top of a reference ellipsoid or geoid )

##discussion: postponed until a real case is met

# spectral polarization data
#concept :spatial matrix
rationale: helps to identify or characterize measurement type

proposal: phys.polarization.coherenceMatrix
definition: coherence matrix of radio signals
usage phys.polarisation.coherenceMatrix:instr
tag:Q

##answer add Q | phys.polarization.coherency | Matrix of the correlation between components of an electromagnetic wave

This will work for all electromagnetic signals and not only in radio regime

not compatible to instr branch in the UCD tree.