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diff --git a/docs/source/operations/transformations/defmodel.rst b/docs/source/operations/transformations/defmodel.rst new file mode 100644 index 00000000..fe2ac66a --- /dev/null +++ b/docs/source/operations/transformations/defmodel.rst @@ -0,0 +1,61 @@ +.. _defmodel: + +================================================================================ +Multi-component time-based deformation model +================================================================================ + +.. versionadded:: 7.1.0 + ++---------------------+--------------------------------------------------------------------+ +| **Input type** | Geodetic or projected coordinates (horizontal), meters (vertical), | +| | decimalyear (temporal) | ++---------------------+--------------------------------------------------------------------+ +| **Output type** | Geodetic or projected coordinates (horizontal), meters (vertical), | +| | decimalyear (temporal) | ++---------------------+--------------------------------------------------------------------+ +| **Domain** | 4D | ++---------------------+--------------------------------------------------------------------+ +| **Available forms** | Forward and inverse | ++---------------------+--------------------------------------------------------------------+ + +The defmodel transformation can be used to represent most deformation models +currently in use, in particular for areas subject to complex deformation, including +large scale secular crustal deformation near plate boundaries and vertical deformation +due to Glacial Isostatic Adjustment (GIA). These can often be represented by a constant +velocity model. Additionally, many areas suffer episodic deformation events such as +earthquakes and aseismic slow slip event. + +The transformation relies on a "master" JSON file, describing general metadata on +the deformation model, its spatial and temporal extent, and listing spatial +components whose values are stored in :ref:`Geodetic TIFF grids (GTG) <geodetictiffgrids>`. +The valuation of each component is modulated by a time function (constant, step, +reverse step, velocity, piecewise, exponential). + +All details on the content of this JSON file are given in the `Proposal for encoding +of a Deformation Model <https://github.com/linz/deformation-model-format/blob/master/doc/JsonGeotiffDeformationModelFormat_20200501.pdf>`__ + +If input coordinates are given in the geographic domain (resp. projected domain), +the output will also be in the geographic domain (resp. projected domain). +The domain should be the corresponding to the source_crs metadata of the model. + +This transformation is a generalization of the :ref:`Kinematic datum shifting utilizing a deformation model <deformation>` transformation. + +Parameters +------------------------------------------------------------------------------- + +Required ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ + +.. option:: +model=<filename> + + Filename to the JSON master file for the deformation model. + + +Example +------------------------------------------------------------------------------- + +Transformating a point with the LINZ NZGD2000 deformation model: + +:: + + echo 166.7133850980 -44.5105886020 293.3700 2007.689 | cct +proj=defmodel +model=nzgd2000-20180701.json |