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diff --git a/docs/source/usage/operations/pipeline.rst b/docs/source/usage/operations/pipeline.rst deleted file mode 100644 index 18637712..00000000 --- a/docs/source/usage/operations/pipeline.rst +++ /dev/null @@ -1,98 +0,0 @@ -.. _pipeline: - -================================================================================ -The pipeline operator -================================================================================ - -Construct complex operations by daisy-chaining operations in a sequential pipeline. - -+-----------------+--------------------------------------------------------------------+ -| **Input type** | Any. | -+-----------------+--------------------------------------------------------------------+ -| **Output type** | Any. | -+-----------------+--------------------------------------------------------------------+ -| **Options** | -+-----------------+--------------------------------------------------------------------+ -| `step` | Separate each step in a pipeline. | -+-----------------+--------------------------------------------------------------------+ -| `inv` | Invert a step in a pipeline. | -+-----------------+--------------------------------------------------------------------+ - -.. note:: See the section on :ref:`transformation` for a more thorough introduction - to the concept of transformation pipelines in PROJ. - - -With the pipeline operation it is possible to perform several operations after each -other on the same input data. This feature makes it possible to create transformations -that are made up of more than one operation, e.g. performing a datum shift and then -applying a suitable map projection. Theoretically any transformation between two -coordinate reference systems is possible to perform using the pipeline operation, -provided that the necessary coordinate operations in each step is available in PROJ. - -A pipeline is made up of a number of steps, with each step being a coordinate operation -in itself. By connecting these individual steps sequentially we end up with a concatenated -coordinate operation. An example of this is a transformation from geodetic coordinates -on the GRS80 ellipsoid to a projected system where the east-west and north-east axes has -been swapped: - -:: - - +proj=pipeline +ellps=GRS80 +step +proj=merc +step +proj=axisswap +order=2,1 - -Here the first step is applying the :ref:`merc` projection and the second step is -applying the :ref:`axisswap` conversion. Note that the `+ellps=GRS80` is specified -before the first occurence of `+step`. This means that the GRS80 ellipsoid is used -in both steps, since any parameter stated before the first occurence of `+step` is -treated as a global parameter and is transferred to each individual steps. - - -Rules for pipelines -------------------------------------------------------------------------------- - -**1. Pipelines must consist of at least one step.** - -:: - - +proj=pipeline - -Will result in an error. - -**2. Pipelines can only be nested if the nested pipeline is defined in an init-file.** - -:: - - +proj=pipeline - +step +proj=pipeline +step +proj=merc +step +proj=axisswap +order=2,1 - +step +proj=unitconvert +xy_in=m +xy_out=us-ft - -Results in an error, while - -:: - - +proj=pipeline - +step +init=predefined_pipelines:projectandswap - +step +proj=unitconvert +xy_in=m +xy_out=us-ft - -does not. - -**3. Pipelines without a forward path can't be constructed.** - -:: - - +proj=pipeline +step +inv +proj=urm5 - -Will result in an error since :ref:`urm5` does not have an inverse operation defined. - -**4. Parameters added before the first `+step` are global and will be applied to all steps.** - -In the following the GRS80 ellipsoid will be applied to all steps. - -:: - - +proj=pipeline +ellps=GRS80 - +step +proj=cart - +step +proj=helmert +x=10 +y=3 +z=1 - +step +proj=cart +inv - +step +proj=merc - - |