The following sub-sections present all packages in the model with their types.
The packages are listed here in alphabetical order.
Each sub-section contains a description of the package and a table containing its various features.
| vodml-id |
feature type |
description |
|
vo-dml:model |
This model defines objects and datatypes which represent 'measured' or 'determined' data. It associates a Coordinate (ie:
the determined value with associated physical context) with corresponding Error(s). As such, this model is at least the foundation
for representing the vast majority of the Astronomical data found in catalogs and data products.
We define here, several specialized classes which cover the most basic and common types, such as Position and Time. We also
provide a generic model which can accommodate virtually any data, but may require a bit more effort to fully describe the
coordinate metadata. Additional specializations, e.g. Flux, Magnitude, Luminosity, Pressure, Temperature, etc. may be added
to this model, or in other models focusing on particular domains or use cases.
We include a fairly simple Error model, describing errors as a 'shape' of uncertainty, and define a small set of commonly
occuring forms (e.g. Symmetrical, Bounds, Ellipsoid).
|
| Asymmetrical1D |
dataType |
Uncertainty with different extent in the positive and negative directions from the associated Coordinate. |
| Asymmetrical1D.minus |
attribute |
Extent in the negative axis direction. |
| Asymmetrical1D.plus |
attribute |
Extent in the positive axis direction. |
| Asymmetrical2D |
dataType |
2D Uncertainty with different extent in the positive and negative axis directions from the associated Coordinate. i.e.: an
offset rectangle.
|
| Asymmetrical2D.minus |
attribute |
Extent in each negative axis direction. |
| Asymmetrical2D.plus |
attribute |
Extent in each positive axis direction. |
| Asymmetrical3D |
dataType |
3D Uncertainty with different extent in the positive and negative axis directions from the associated Coordinate. i.e.: an
offset box.
|
| Asymmetrical3D.minus |
attribute |
Extent in each negative axis direction. |
| Asymmetrical3D.plus |
attribute |
Extent in each positive axis direction. |
| Bounds1D |
dataType |
Provide the edges of the uncertainty space. Rather than being relative to the associated Coordinate, these represent a range
within that Coordinate space.
|
| Bounds1D.hiLimit |
attribute |
Upper limit of the uncertainty range. |
| Bounds1D.loLimit |
attribute |
Lower limit of the uncertainty range. |
| Bounds2D |
dataType |
Provide the edges of a 2D uncertainty space. Rather than being relative to the associated Coordinate, these represent ranges
along each axis of that Coordinate space.
|
| Bounds2D.hiLimit |
attribute |
Upper edges of the uncertainty rectangle. |
| Bounds2D.loLimit |
attribute |
Lower edges of the uncertainty rectangle. |
| Bounds3D |
dataType |
Provide the edges of a 3D uncertainty space. Rather than being relative to the associated Coordinate, these represent ranges
along each axis of that Coordinate space.
|
| Bounds3D.hiLimit |
attribute |
Upper edges of the uncertainty box. |
| Bounds3D.loLimit |
attribute |
Lower edges of the uncertainty box. |
| Ellipse |
dataType |
Elliptical uncertainty shape. |
| Ellipse.posAngle |
attribute |
Position angle, counter-clockwise from the positive direction of the first axis of the associated Coordinate. When used in
the spatial domain, the expectation is that the 'first axis' corresponds to the 'North Celestial Pole', and the second to
'East', thereby conforming to the IAU definition of the position angle direction being 'East of North'.
|
| Ellipse.semiAxis |
attribute |
Extent of the semi-major and semi-minor axes, provided in the order of the associated Coordinate axes. |
| Ellipsoid |
dataType |
Ellipsoidal uncertainty shape. |
| Ellipsoid.posAngle |
attribute |
Position angles
* counter-clockwise from the positive direction of the first axis toward the second axis
* angle 'above' the plane of the first two axes of the associated Coordinate.
When used in the spatial domain, the expectation is that the 'first axis' corresponds to the 'North Celestial Pole', and the
second to 'East', thereby conforming to the IAU definition of the position angle direction being 'East of North'.
|
| Ellipsoid.semiAxis |
attribute |
Extent of the semi axes, provided in the order of the associated Coordinate axes. |
| Error |
objectType |
The Error class uses the Uncertainty types to describe measurement errors from various sources. |
| Error.statError |
attribute |
Statistical error. The Uncertainty type MUST be dimensionally compatible with the associated Measure value. |
| Error.sysError |
attribute |
Systematic error. The Uncertainty type MUST be dimensionally compatible with the associated Measure value. |
| GenericMeasure |
objectType |
The most generic Measure class. This class may be used to represent data not covered by the specialized cases. |
| GenericMeasure.coord |
attribute |
The measured coordinate value. |
| Measure |
objectType |
Abstract base of Measure classes, associates a 'determined value' (Coordinate) with corresponding errors.
We associate the Error(s) with the full Measure, rather than the individual values, in order to support both correlated and
uncorrelated errors. In many cases with multi-dimensional data, the associated errors are correlated and must be considered
with the value set as a whole. One consequence of this approach is that there is a looser association between the Error dimensions
and the corresponding value dimension. We require that the Error content MUST be compatible with the value dimension and
nature (e.g. dimension, domain, units, etc).
|
| Measure.error |
composition |
Measurement error. |
| Polarization |
objectType |
Provides a complete description of a determined polarization state. Since the polarization coordinate is an enumerated type,
there can be no associated numerical error sources.
|
| Polarization.coord |
attribute |
Determined polarization state. May be provided by any of the PolCoordValue subtypes. |
| Position |
objectType |
Provides a complete description of a measured positional instant. |
| Position.coord |
attribute |
The measured Position value. The Point coordinate supports 1,2, and 3-dimensional cases. Details of the coordinate system
(space and frame), are associated with the Point.
|
| ProperMotion |
objectType |
Proper motion represented as the velocity in Longitude and Latitude directions of a spherical coordinate space. The associated
SpaceFrame provides the details regarding the nature of the coordinate space (eg: Equatorial, Galactic, etc).
|
| ProperMotion.lat |
attribute |
Velocity in angular distance per unit time along the Latitude axis. |
| ProperMotion.lon |
attribute |
Velocity in angular distance per unit time along the Longitude axis. It is common, though not universal, practice to quote
longitudinal proper motion pre-multiplied by cos(lat) so that the magnitude of the quantity is not affected by its longitudinal
position. We do not constrain this value to one form or the other in this model, leaving it to be specified by the particular
usage thread.
|
| Symmetrical |
dataType |
Symmetrical uncertainty, constant in all dimensions and directions from the associated Coordinate. ie: PlusMinus in 1D, circular
in 2D, spherical in 3D.
|
| Symmetrical.radius |
attribute |
The uncertainty extent, constant in all dimensions and directions. |
| Time |
objectType |
Provides a complete description of a measured Temporal instant. |
| Time.coord |
attribute |
The measured time value. May be provided in any of the TimeStamp subtypes. |
| Uncertainty |
dataType |
Abstract head of uncertainty types. These classes define the shape of the uncertainty, and are designed to be reusable in
different contexts. Uncertainties are designed to be associated with a Coordinate or other object which provides the 'center'
or reference location about which the uncertainty resides. In this model, we use them in the context of defining measurement
errors, but they are also compatible for use in defining resolutions which are to be modeled at a later date.
This initial version of teh model forms a fundamental basis which can then be expanded to include more complex and varied
use cases as they present themselves. The current model assumes Gaussian distributions with shpes defined at the 68% confidence
level.
|
| Velocity |
objectType |
Provides a comple description of a measured Velocity instant. |
| Velocity.coord |
attribute |
The measured Velocity value. The Point coordinate supports 1,2, and 3-dimensional cases. Details of the coordinate system
(space and frame), are associated with the Point.
|
This section lists the external models imported by the current data model.
For each imported model we list URLs to the VO-DML and HTML representations and the prefix used for vodml-ids from inside
the model.
