From 9f908ae47cfa70d3cdb2709a8ab5d8eeb10034fc Mon Sep 17 00:00:00 2001 From: Even Rouault Date: Mon, 9 Dec 2019 23:26:39 +0100 Subject: Horizontal shift grids: hide the 'positive longitude shift value = westward correction' in the CTable2/NTv1/NTv2 backends --- src/grids.cpp | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'src/grids.cpp') diff --git a/src/grids.cpp b/src/grids.cpp index 7d19b1f7..cc954542 100644 --- a/src/grids.cpp +++ b/src/grids.cpp @@ -469,7 +469,8 @@ bool NTv1Grid::valueAt(int x, int y, float &lonShift, float &latShift) const { } /* convert seconds to radians */ latShift = static_cast(two_doubles[0] * ((M_PI / 180.0) / 3600.0)); - lonShift = static_cast(two_doubles[1] * ((M_PI / 180.0) / 3600.0)); + // west longitude positive convention ! + lonShift = -static_cast(two_doubles[1] * ((M_PI / 180.0) / 3600.0)); return true; } @@ -572,7 +573,8 @@ bool CTable2Grid::valueAt(int x, int y, float &lonShift, } latShift = two_floats[1]; - lonShift = two_floats[0]; + // west longitude positive convention ! + lonShift = -two_floats[0]; return true; } @@ -642,7 +644,8 @@ bool NTv2Grid::valueAt(int x, int y, float &lonShift, float &latShift) const { } /* convert seconds to radians */ latShift = static_cast(two_float[0] * ((M_PI / 180.0) / 3600.0)); - lonShift = static_cast(two_float[1] * ((M_PI / 180.0) / 3600.0)); + // west longitude positive convention ! + lonShift = -static_cast(two_float[1] * ((M_PI / 180.0) / 3600.0)); return true; } -- cgit v1.2.3