Package pygeodesy :: Module trf |
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# Module trf

Veness' Terrestrial Reference Frames (TRF).

Classes RefFrame, registry RefFrames and TRFError.

Transcoded from Chris Veness' (C) 2006-2022 JavaScript originals latlon-ellipsoidal-referenceframe.js and latlon-ellipsoidal-referenceframe-txparams.js.

Following is a copy of the comments in Veness' latlon-ellipsoidal-referenceframe.js.

Modern geodetic reference frames: a latitude/longitude point defines a geographic location on, above or below the earth’s surface, measured in degrees from the equator and the International Reference Meridian (IRM) and metres above the ellipsoid within a given Terrestrial Reference Frame at a given epoch.

This is scratching the surface of complexities involved in high precision geodesy, but may be of interest and/or value to those with less demanding requirements. More information here and here.

Note that ITRF solutions do not directly use an ellipsoid, but are specified by Cartesian coordinates. The GRS80 ellipsoid is recommended for transformations to geographical coordinates.

Note WGS84(G730/G873/G1150) are coincident with ITRF at 10-centimetre level, see also here. WGS84(G1674) and ITRF20014 / ITRF2008 "are likely to agree at the centimeter level", see also QPS/Qinsy.

Version: 24.02.12

Classes
| RefFrame Terrestrial Reference Frame (TRF) parameters.
| TransformXform Helmert transformation, extended with an `Xform` converter.
| TRFXform7Tuple 7-Tuple `(tx, ty, tz, s, sx, sy, sz)` of conversion parameters with translations `tx`, `ty` and `tz` in `milli-meter`, scale `s` in `ppb` and rates `sx`, `sy` and `sz` in `milli-arc-seconds-per-year`.
| TRFXform A Terrestrial Reference Frame (TRF) converter between two reference frames observed at an `epoch`.

Functions
date2epoch(year, month, day) Return the `epoch` for a calendar day. |
epoch2date(epoch) Return the date for a reference frame `epoch`. |
trfTransform0(reframe, reframe2, epoch=None, epoch2=None, indirect=True, inverse=True) Get a Helmert transform to convert one `reframe` observed at `epoch` to an other `reframe2` at observed at `epoch2 or epoch`. |
trfTransforms(reframe, reframe2, epoch=None, epoch2=None, indirect=True, inverse=True) Yield all Helmert transform to convert one `reframe` observed at `epoch` to an other `reframe2` at observed at `epoch2 or epoch`. |
trfXform(reframe1, reframe2, epoch=None, xform=None, rates=None) Define a new Terrestrial Reference Frame (TRF) converter or get an existing one. |

Variables
| __all__ = `_ALL_LAZY.trf`
| RefFrames = `RefFrames.ETRF89: RefFrame(name='ETRF89', epoch=19`...`` Some pre-defined RefFrames, all lazily instantiated.
| RefFrames.ETRF2000 RefFrame(name='ETRF2000', epoch=2005, datum=Datums.GRS80) .Xforms=(0, -14)
| RefFrames.ETRF2005 RefFrame(name='ETRF2005', epoch=2005, datum=Datums.GRS80) .Xforms=(0, -1)
| RefFrames.ETRF2008 RefFrame(name='ETRF2008', epoch=2008, datum=Datums.GRS80) .Xforms=(0, 0)
| RefFrames.ETRF2014 RefFrame(name='ETRF2014', epoch=2014, datum=Datums.GRS80) .Xforms=(0, -14)
| RefFrames.ETRF2020 RefFrame(name='ETRF2020', epoch=2020, datum=Datums.GRS80) .Xforms=(0, -14)
| RefFrames.ETRF88 RefFrame(name='ETRF88', epoch=1988, datum=Datums.GRS80) .Xforms=(0, 0)
| RefFrames.ETRF89 RefFrame(name='ETRF89', epoch=1989, datum=Datums.GRS80) .Xforms=(0, -1)
| RefFrames.ETRF90 RefFrame(name='ETRF90', epoch=1990, datum=Datums.GRS80) .Xforms=(0, -1)
| RefFrames.ETRF91 RefFrame(name='ETRF91', epoch=1991, datum=Datums.GRS80) .Xforms=(0, -1)
| RefFrames.ETRF92 RefFrame(name='ETRF92', epoch=1992, datum=Datums.GRS80) .Xforms=(0, -1)
| RefFrames.ETRF93 RefFrame(name='ETRF93', epoch=1993, datum=Datums.GRS80) .Xforms=(0, -1)
| RefFrames.ETRF94 RefFrame(name='ETRF94', epoch=1994, datum=Datums.GRS80) .Xforms=(0, -1)
| RefFrames.ETRF96 RefFrame(name='ETRF96', epoch=1996, datum=Datums.GRS80) .Xforms=(0, -1)
| RefFrames.ETRF97 RefFrame(name='ETRF97', epoch=1997, datum=Datums.GRS80) .Xforms=(0, -1)
| RefFrames.GDA2020 RefFrame(name='GDA2020', epoch=2020, datum=Datums.GRS80) .Xforms=(0, -4)
| RefFrames.GDA94 RefFrame(name='GDA94', epoch=1994, datum=Datums.GRS80) .Xforms=(0, -3)
| RefFrames.ITRF2000 RefFrame(name='ITRF2000', epoch=1997, datum=Datums.GRS80) .Xforms=(15, -4)
| RefFrames.ITRF2005 RefFrame(name='ITRF2005', epoch=2000, datum=Datums.GRS80) .Xforms=(8, -3)
| RefFrames.ITRF2008 RefFrame(name='ITRF2008', epoch=2005, datum=Datums.GRS80) .Xforms=(17, -2)
| RefFrames.ITRF2014 RefFrame(name='ITRF2014', epoch=2010, datum=Datums.GRS80) .Xforms=(16, -1)
| RefFrames.ITRF2020 RefFrame(name='ITRF2020', epoch=2015, datum=Datums.GRS80) .Xforms=(16, 0)
| RefFrames.ITRF88 RefFrame(name='ITRF88', epoch=1988, datum=Datums.GRS80) .Xforms=(3, -4)
| RefFrames.ITRF89 RefFrame(name='ITRF89', epoch=1989, datum=Datums.GRS80) .Xforms=(4, -4)
| RefFrames.ITRF90 RefFrame(name='ITRF90', epoch=1988, datum=Datums.GRS80) .Xforms=(6, -4)
| RefFrames.ITRF91 RefFrame(name='ITRF91', epoch=1988, datum=Datums.GRS80) .Xforms=(4, -4)
| RefFrames.ITRF92 RefFrame(name='ITRF92', epoch=1988, datum=Datums.GRS80) .Xforms=(4, -4)
| RefFrames.ITRF93 RefFrame(name='ITRF93', epoch=1988, datum=Datums.GRS80) .Xforms=(4, -4)
| RefFrames.ITRF94 RefFrame(name='ITRF94', epoch=1993, datum=Datums.GRS80) .Xforms=(4, -4)
| RefFrames.ITRF96 RefFrame(name='ITRF96', epoch=1997, datum=Datums.GRS80) .Xforms=(5, -5)
| RefFrames.ITRF97 RefFrame(name='ITRF97', epoch=1997, datum=Datums.GRS80) .Xforms=(5, -4)
| RefFrames.NAD83 RefFrame(name='NAD83', epoch=1997, datum=Datums.GRS80) .Xforms=(0, -5)
| RefFrames.WGS84 RefFrame(name='WGS84', epoch=1984, datum=Datums.GRS80) .Xforms=(0, -1)
| RefFrames.WGS84g1150 RefFrame(name='WGS84g1150', epoch=2001, datum=Datums.GRS80) .Xforms=(0, 0)
| RefFrames.WGS84g1674 RefFrame(name='WGS84g1674', epoch=2005, datum=Datums.GRS80) .Xforms=(0, 0)
| RefFrames.WGS84g1762 RefFrame(name='WGS84g1762', epoch=2005, datum=Datums.GRS80) .Xforms=(0, 0)

Function Details

### date2epoch (year, month, day) |
Return the `epoch` for a calendar day. Arguments: `year` - Year of the date (`scalar`). `month` - Month in the `year` (`scalar`, 1..12). `day` - Day in the `month` (`scalar`, 1..31). Returns: Epoch, the fractional year (`float`). Raises: `TRFError` - Invalid `year`, `month` or `day`. Note: Any `year` is considered a leap year, i.e. having 29 days in February.

### epoch2date (epoch) |
Return the date for a reference frame `epoch`. Arguments: `epoch` - Fractional year (`scalar`). Returns: 3-Tuple `(year, month, day)`. Raises: `TRFError` - Invalid `epoch`. Note: Any `year` is considered a leap year, i.e. having 29 days in February.

### trfTransform0 (reframe, reframe2, epoch=None, epoch2=None, indirect=True, inverse=True) |
Get a Helmert transform to convert one `reframe` observed at `epoch` to an other `reframe2` at observed at `epoch2 or epoch`. Returns: A TransformXform instance, a `0-tuple` for unity, identity or `None` if no conversion exists. See Also: Function trfTransforms for futher details.

### trfTransforms (reframe, reframe2, epoch=None, epoch2=None, indirect=True, inverse=True) |
Yield all Helmert transform to convert one `reframe` observed at `epoch` to an other `reframe2` at observed at `epoch2 or epoch`. Arguments: `reframe` - The frame to convert from (RefFrame or `str`). `reframe2` - The frame to convert to (RefFrame or `str`). `epoch` - Epoch to observe from (Epoch, `scalar` or `str`), otherwise `reframe`'s `epoch`. `epoch2` - Optional epoch to observe to observe to (Epoch, `scalar` or `str`), otherwise `epoch` or `reframe`'s `epoch`. `indirect` - If `True`, include transforms via one intermediate reframe, otherwise only direct `reframe` to `reframe2` transforms (`bool`). `inverse` - If `True`, include inverse, otherwise only forward transforms (`bool`). Returns: A TransformXform instance for each available conversion. Raises: `TRFError` - Invalid `reframe`, `epoch`, `reframe2` or `epoch2`. `TypeError` - Invalid `reframe` or `reframe2`.

### trfXform (reframe1, reframe2, epoch=None, xform=None, rates=None) |
Define a new Terrestrial Reference Frame (TRF) converter or get an existing one. Arguments: `reframe1` - Source frame (RefFrame or `str`), converting from. `reframe2` - Destination frame (RefFrame or `str`), converting to. `epoch` - Epoch, a fractional year (Epoch, `scalar` or `str`) or `None` for `reframe2`'s epoch. `xform` - Transform parameters (TRFXform7Tuple). `rates` - Rate parameters (TRFXform7Tuple), as `xform`, but in `units-per-year`. Returns: The new TRF converter (TRFXform) or if no `epoch`, `xform` and `rates` are given, return the existing one (TRFXform) or `None` if not available. Raises: `TRFError` - Invalid `reframe1`, `reframe2`, `epoch`, `xform` or `rates` or the TRF converter already exists.

Variables Details

  ### RefFrames Some pre-defined RefFrames, all lazily instantiated. Value:
      RefFrames.ETRF89: RefFrame(name='ETRF89', epoch=1989, datum=Datums.GRS
      80),
      RefFrames.GDA2020: RefFrame(name='GDA2020', epoch=2020, datum=Datums.G
      RS80),
      RefFrames.ETRF92: RefFrame(name='ETRF92', epoch=1992, datum=Datums.GRS
      80),
      RefFrames.ETRF93: RefFrame(name='ETRF93', epoch=1993, datum=Datums.GRS
      80),
      ...