diff options
| author | Kristian Evers <kristianevers@gmail.com> | 2019-02-14 14:51:39 +0100 |
|---|---|---|
| committer | Kristian Evers <kristianevers@gmail.com> | 2019-02-14 14:55:23 +0100 |
| commit | 12689e3d858d66e5e00e8d99f9326ef91cc0a384 (patch) | |
| tree | d797ce54ab1a2d8539204f70d3aa59ba66f603ae /docs/source/usage | |
| parent | 365526921aa330fbfb185569cbfbb54ca5714f6c (diff) | |
| download | PROJ-12689e3d858d66e5e00e8d99f9326ef91cc0a384.tar.gz PROJ-12689e3d858d66e5e00e8d99f9326ef91cc0a384.zip | |
deformation: Replace +t_obs with +dt
The +t_obs parameter was confusing for users since it effectively
overwrote the observation time in input coordinates. To make it more clear
what is the operation is doing, users are now required to directly specify
the time span for which they wish to apply a given deformation. The parameter
+dt has been added for that purpose. The new parameter is mutually
exclusive with +t_epoch. +dt is used when deformation
for a set amount of time is needed and +t_epoch is used (in
conjunction with the observation time of the input coordinate) when
deformation from a specific epoch to the observation time is needed.
Diffstat (limited to 'docs/source/usage')
| -rw-r--r-- | docs/source/usage/differences.rst | 27 |
1 files changed, 25 insertions, 2 deletions
diff --git a/docs/source/usage/differences.rst b/docs/source/usage/differences.rst index b7c79f53..d5eebe8e 100644 --- a/docs/source/usage/differences.rst +++ b/docs/source/usage/differences.rst @@ -72,8 +72,15 @@ default ellipsoid is GRS80 (was WGS84 in previous PROJ versions). Changes to :ref:`deformation<deformation>` ------------------------------------------------------------------ +.. _differences_deformation: -In the initial version of the of :ref:`deformation<deformation>` operation the time span between :math:`t_{obs}` and :math:`t_c` was determine by the expression + +Reversed order of operation +........................... + +In the initial version of the of :ref:`deformation<deformation>` operation +the time span between :math:`t_{obs}` and :math:`t_c` was determined by the +expression .. math:: @@ -90,4 +97,20 @@ Effectively this means that the direction of the operation has been reversed, so that what in PROJ 5 was a forward operation is now an inverse operation and vice versa. -Pipelines written for PROJ 5 can be migrated to PROJ 6 by adding :option:`+inv` to forward steps involving the deformation operation. Similarly :option:`+inv` should be removed from inverse steps to be compatible with PROJ 6. +Pipelines written for PROJ 5 can be migrated to PROJ 6 by adding :option:` ++inv` to forward steps involving the deformation operation. Similarly +:option:`+inv` should be removed from inverse steps to be compatible with +PROJ 6. + +Removed ``+t_obs`` parameter +............................. + +The ``+t_obs`` parameter was confusing for users since it effectively +overwrote the observation time in input coordinates. To make it more clear +what is the operation is doing, users are now required to directly specify +the time span for which they wish to apply a given deformation. The parameter +:option:`+dt` has been added for that purpose. The new parameter is mutually +exclusive with :option:`+t_epoch`. :option:`+dt` is used when deformation +for a set amount of time is needed and :option:`+t_epoch` is used (in +conjunction with the observation time of the input coordinate) when +deformation from a specific epoch to the observation time is needed.
\ No newline at end of file |