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-rw-r--r--src/grids.cpp9
1 files changed, 6 insertions, 3 deletions
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<float>(two_doubles[0] * ((M_PI / 180.0) / 3600.0));
- lonShift = static_cast<float>(two_doubles[1] * ((M_PI / 180.0) / 3600.0));
+ // west longitude positive convention !
+ lonShift = -static_cast<float>(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<float>(two_float[0] * ((M_PI / 180.0) / 3600.0));
- lonShift = static_cast<float>(two_float[1] * ((M_PI / 180.0) / 3600.0));
+ // west longitude positive convention !
+ lonShift = -static_cast<float>(two_float[1] * ((M_PI / 180.0) / 3600.0));
return true;
}