From f201a86386b9c8fa183b3f9855a4087a9a800f4e Mon Sep 17 00:00:00 2001 From: Even Rouault Date: Sat, 25 Jan 2020 16:31:00 +0100 Subject: Fix ingestion of +proj=cea with +k_0 Fixes #1881 Digging into the implementation of proj=cea, it appears that k_0 and lat_ts are intended to be exclusive ways of specifying the same concept. EPSG only models the variant using lat_s. So if k_0 is found and lat_ts is absent, compute the equivalent value of lat_ts from k_0. Note: k_0 should normally be in the [0,1] range. In case creative users would use something outside, we raise an exception, even if the cea implementation could potentially deal with any k_0 value. Hopefully this is a (reasonable) limitation that will address nominal use cases. --- docs/source/operations/projections/cea.rst | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'docs/source/operations') diff --git a/docs/source/operations/projections/cea.rst b/docs/source/operations/projections/cea.rst index 4542fe71..80fe1df3 100644 --- a/docs/source/operations/projections/cea.rst +++ b/docs/source/operations/projections/cea.rst @@ -29,3 +29,9 @@ Parameters .. include:: ../options/x_0.rst .. include:: ../options/y_0.rst + +.. note:: + + ``lat_ts`` and ``k_0`` are mutually exclusive. If ``lat_ts`` + is specified, it is equivalent to setting ``k_0`` to + :math:`\frac{\cos \phi_{ts}}{\sqrt{1 - e^2 \sin^2 \phi_{ts}}}` \ No newline at end of file -- cgit v1.2.3