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Diffstat (limited to 'docs/source/operations/projections/gall.rst')
| -rw-r--r-- | docs/source/operations/projections/gall.rst | 48 |
1 files changed, 34 insertions, 14 deletions
diff --git a/docs/source/operations/projections/gall.rst b/docs/source/operations/projections/gall.rst index b9120d9f..bdb88895 100644 --- a/docs/source/operations/projections/gall.rst +++ b/docs/source/operations/projections/gall.rst @@ -7,22 +7,26 @@ Gall (Gall Stereographic) The Gall stereographic projection, presented by James Gall in 1855, is a cylindrical projection. It is neither equal-area nor conformal but instead tries to balance the distortion inherent in any projection. -+---------------------+--------------------------------------------------------------------------------+ -| **Classification** | Transverse and oblique cylindrical | -+---------------------+--------------------------------------------------------------------------------+ -| **Available forms** | Forward and inverse, Spherical | -+---------------------+--------------------------------------------------------------------------------+ -| **Defined area** | Global | -+---------------------+--------------------------------------------------------------------------------+ -| **Implemented by** | Gerald I. Evenden | -+---------------------+--------------------------------------------------------------------------------+ -| **Options** | No special options for this projection | -+---------------------+--------------------------------------------------------------------------------+ ++---------------------+----------------------------------------------------------+ +| **Classification** | Transverse and oblique cylindrical | ++---------------------+----------------------------------------------------------+ +| **Available forms** | Forward and inverse, Spherical | ++---------------------+----------------------------------------------------------+ +| **Defined area** | Global | ++---------------------+----------------------------------------------------------+ +| **Alias** | gall | ++---------------------+----------------------------------------------------------+ +| **Domain** | 2D | ++---------------------+----------------------------------------------------------+ +| **Input type** | Geodetic coordinates | ++---------------------+----------------------------------------------------------+ +| **Output type** | Projected coordinates | ++---------------------+----------------------------------------------------------+ .. image:: ./images/gall.png :scale: 50% - :alt: Gall (Gall Stereographic) + :alt: Gall (Gall Stereographic) Usage ##### @@ -38,7 +42,7 @@ Unlike the Mercator, the Gall shows the poles as lines running across the top an Example using Gall Stereographical :: - $ echo 9 51 | proj +proj=gall +lon_0=0 +x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m +no_defs + $ echo 9 51 | proj +proj=gall +lon_0=0 +x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m +no_defs 708432.90 5193386.36 Example using Gall Stereographical (Central meridian 90°W) :: @@ -46,6 +50,22 @@ Example using Gall Stereographical (Central meridian 90°W) :: $ echo 9 51 | proj +proj=gall +lon_0=90w +x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m +no_defs 7792761.91 5193386.36 +Parameters +################################################################################ + +.. note:: All parameters for the projection are optional. + +.. include:: ../options/lon_0.rst + +.. include:: ../options/R.rst + +.. include:: ../options/x_0.rst + +.. include:: ../options/y_0.rst + +.. include:: ../options/ellps.rst + + Mathematical definition ####################### @@ -70,7 +90,7 @@ Inverse projection .. math:: - \phi = 2 \arctan( \frac{y}{1+\frac{\sqrt{2}}{2}} ) + \phi = 2 \arctan( \frac{y}{1+\frac{\sqrt{2}}{2}} ) .. math:: |