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-rw-r--r--docs/source/operations/projections/ob_tran.rst11
1 files changed, 6 insertions, 5 deletions
diff --git a/docs/source/operations/projections/ob_tran.rst b/docs/source/operations/projections/ob_tran.rst
index 378f1333..3a23259d 100644
--- a/docs/source/operations/projections/ob_tran.rst
+++ b/docs/source/operations/projections/ob_tran.rst
@@ -19,9 +19,10 @@ oblique projection by means of the General Oblique Transformation. The user
performs the oblique transformation by selecting the oblique projection
``+proj=ob_tran``, specifying the translation factors, :option:`+o_lat_p`, and
:option:`+o_lon_p`, and the projection to be used, :option:`+o_proj`. In the
-example of the Fairgrieve projection the latitude and longitude of the pole of
-the new coordinates, :math:`\alpha` and :math:`\beta` respectively, are to be placed
-at 45°N and 90°W and use the :ref:`moll` projection. Because the central meridian
+example of the Fairgrieve projection, the latitude and longitude of the North pole
+of the unrotated geographic CRS, :math:`\alpha` and :math:`\beta` respectively,
+expressed in the rotated geographic CRS, are to be placed
+at 45°N and 90°W and the :ref:`moll` projection is used. Because the central meridian
of the translated coordinates will follow the :math:`\beta` meridian it is
necessary to translate the translated system so that the Greenwich meridian
will pass through the center of the projection by offsetting the central meridian.
@@ -50,11 +51,11 @@ New pole
.. option:: +o_lat_p=<latitude>
- Latitude of new pole for oblique projection.
+ Latitude of the North pole of the unrotated source CRS, expressed in the rotated geographic CRS.
.. option:: +o_lon_p=<longitude>
- Longitude of new pole for oblique projection.
+ Longitude of the North pole of the unrotated source CRS, expressed in the rotated geographic CRS.
Rotate about point
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