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| author | Kristian Evers <kristianevers@gmail.com> | 2017-09-18 22:21:20 +0200 |
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| committer | Kristian Evers <kristianevers@gmail.com> | 2017-09-18 22:21:20 +0200 |
| commit | 6d1a1ff4e470bb4d26be46bdf01de3d94e6ab8e9 (patch) | |
| tree | 7bec3d77463fba3ff68ebabcc127ad504da0836d /docs/source/usage/operations/transformations/vgridshift.rst | |
| parent | 1f60b8c407ac202916cf4570683935fcca451531 (diff) | |
| download | PROJ-6d1a1ff4e470bb4d26be46bdf01de3d94e6ab8e9.tar.gz PROJ-6d1a1ff4e470bb4d26be46bdf01de3d94e6ab8e9.zip | |
Moved projection list to using chapter and created a list of transformations. Both are grouped in a section called operations.
Diffstat (limited to 'docs/source/usage/operations/transformations/vgridshift.rst')
| -rw-r--r-- | docs/source/usage/operations/transformations/vgridshift.rst | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/docs/source/usage/operations/transformations/vgridshift.rst b/docs/source/usage/operations/transformations/vgridshift.rst new file mode 100644 index 00000000..f48d40c8 --- /dev/null +++ b/docs/source/usage/operations/transformations/vgridshift.rst @@ -0,0 +1,34 @@ +.. _vgridshift: + +================================================================================ +Vertical grid shift +================================================================================ + +Change Vertical datum change by grid shift + ++--------------+--------------------------------------------------------------------+ +| **Options** | ++--------------+--------------------------------------------------------------------+ +| `+grids` | Comma-separated list of grids to load. | ++--------------+--------------------------------------------------------------------+ + +The vertical grid shift is done by offsetting the vertical input coordinates by +a specific amount determined by the loaded grids. The simplest use case of the +horizontal grid shift is applying a single grid. Here we change the vertical +reference from the ellipsoid to the global geoid model, EGM96:: + + +vgridshift +grids=egm96_16.gtx + + +More than one grid can be loaded at the same time, for instance in the case where +a better geoid model than the global is available for a certain area. Here the +gridshift is set up so that the local DVR90 geoid model takes presedence over +the global model:: + + +vgridshift +grids=@dvr90.gtx,egm96_16.gtx + +The ``@`` in the above example states that the grid is optional, in case the grid +is not found in the PROJ.4 search path. The list of grids is prioritized so that +grids in the start of the list takes presedence over the grids in the back of the +list. + |