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Diffstat (limited to 'docs/source/operations/transformations/deformation.rst')
| -rw-r--r-- | docs/source/operations/transformations/deformation.rst | 60 |
1 files changed, 48 insertions, 12 deletions
diff --git a/docs/source/operations/transformations/deformation.rst b/docs/source/operations/transformations/deformation.rst index f10562dd..f3cb9307 100644 --- a/docs/source/operations/transformations/deformation.rst +++ b/docs/source/operations/transformations/deformation.rst @@ -4,6 +4,8 @@ Kinematic datum shifting utilizing a deformation model ================================================================================ +.. versionadded:: 5.0.0 + Perform datum shifts means of a deformation/velocity model. +-----------------+--------------------------------------------------------------------+ @@ -11,19 +13,14 @@ Perform datum shifts means of a deformation/velocity model. +-----------------+--------------------------------------------------------------------+ | **Output type** | Cartesian coordinates (spatial), decimalyears (temporal). | +-----------------+--------------------------------------------------------------------+ -| **Options** | -+-----------------+--------------------------------------------------------------------+ -| `xy_grids` | Comma-separated list of grids to load. *Required*. | -+-----------------+--------------------------------------------------------------------+ -| `z_grids` | Comma-separated list of grids to load. *Required*. | ++ **Domain** | 4D | +-----------------+--------------------------------------------------------------------+ -| `t_epoch` | Central epoch of transformation. [decimalyear]. *Required*. | +| **Input type** | Geodetic coordinates | +-----------------+--------------------------------------------------------------------+ -| `t_obs` | Observation time of coordinate(s). [decimalyear]. *Optional*. | -| | If not specified, will be get from the t component of 4D input | -| | points. | +| **Output type** | Geodetic coordinates | +-----------------+--------------------------------------------------------------------+ + The deformation operation is used to adjust coordinates for intraplate deformations. Usually the transformation parameters for regional plate-fixed reference frames such as the ETRS89 does not take intraplate deformation into account. It is assumed that @@ -49,6 +46,7 @@ official ETRS89 transformations so in order to get accurate transformations in t countries it is necessary to apply the deformation model. The transformation from ITRF2008 to the Danish realisation of ETRS89 is in PROJ described as:: + proj = pipeline ellps = GRS80 # ITRF2008@t_obs -> ITRF2000@t_obs step init = ITRF2008:ITRF2000 @@ -81,8 +79,46 @@ model. The first use of the deformation operation is:: Here we set the central epoch of the transformation, 2000.0. The observation epoch is expected as part of the input coordinate tuple. The deformation model is -described by two grids, specified with *xy_grids* and *z_grids*. The first is -the horizontal part of the model and the second is the vertical component. +described by two grids, specified with :option:`+xy_grids` and :option:`+z_grids`. +The first is the horizontal part of the model and the second is the vertical +component. + +Parameters +------------------------------------------------------------------------------- + +Required +################################################################################ + + +.. option:: +xy_grids=<list> + + Comma-separated list of grids to load. If a grid is prefixed by an `@` the + grid is consideres optional and PROJ will the not complain if the grid is + not available. + + Grids for the horizontla component of a deformation model is expected to be + in CTable2 format. + +.. option:: +z_grids=<list> + + Comma-separated list of grids to load. If a grid is prefixed by an `@` the + grid is consideres optional and PROJ will the not complain if the grid is + not available. + + Grids for the vertical component of a deformation model is expected to be + in either GTX format. + +.. option:: +t_epoch=<value> + + Central epoch of transformation given in decimalyears. + +Optional +################################################################################ + +.. option:: +t_obs=<value> + + Observation time of coordinate(s) given in decimalyears. If not specified, + the observation time from the temporal component of 4D input points is used. Mathematical description ------------------------------------------------------------------------------- @@ -122,7 +158,7 @@ Coordinates of the gridded model are in ENU (east, north, up) space because it w otherwise require an enormous 3 dimensional grid to handle the corrections in cartesian space. Keeping the correction in lat/long space reduces the complexity of the grid significantly. Consequently though, the input coordinates needs to be converted to -lat/long space when searching for corrections in the grid. This is done with *cart* +lat/long space when searching for corrections in the grid. This is done with the *cart* operation. The converted grid corrections can then be applied to the input coordinates in cartesian space. The conversion from ENU space to cartesian space is done in the following way: |