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Update EWA ll2cr_static to handle swaths crossing the anti-meridian. #376

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Sep 16, 2021
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Update EWA ll2cr_static to handle swaths crossing the anti-meridian. #376

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4 changes: 0 additions & 4 deletions pyresample/ewa/_ll2cr.pyx
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Original file line number Diff line number Diff line change
Expand Up @@ -232,7 +232,6 @@ def ll2cr_static(numpy.ndarray[cr_dtype, ndim=2] lon_arr, numpy.ndarray[cr_dtype
cdef tuple projected_tuple = p(lon_arr, lat_arr)
cdef cr_dtype [:, ::1] rows_out = projected_tuple[1]
cdef cr_dtype [:, ::1] cols_out = projected_tuple[0]
cdef double proj_circum = projection_circumference(p)

# indexes
cdef unsigned int row
Expand All @@ -252,9 +251,6 @@ def ll2cr_static(numpy.ndarray[cr_dtype, ndim=2] lon_arr, numpy.ndarray[cr_dtype
lon_arr[row, col] = fill_in
lat_arr[row, col] = fill_in
continue
elif proj_circum != 0 and abs(x_tmp - origin_x) >= (0.75 * proj_circum):
# if x is more than 75% around the projection space, it is probably crossing the anti-meridian
x_tmp += proj_circum

x_tmp = (x_tmp - origin_x) / cell_width
y_tmp = (y_tmp - origin_y) / cell_height
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36 changes: 35 additions & 1 deletion pyresample/test/test_ewa_ll2cr.py
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Expand Up @@ -50,6 +50,17 @@
"proj4_definition": "+proj=lcc +a=6371200 +b=6371200 +lat_0=25 +lat_1=25 +lon_0=-95 +units=m +no_defs",
}

static_geo_whole_earth = {
"grid_name": "test_geo",
"origin_x": -180.0,
"origin_y": 40,
"width": 361,
"height": 181,
"cell_width": 1.0,
"cell_height": 1.0,
"proj4_definition": "+proj=longlat +datum=WGS84 +no_defs +type=crs",
}


class TestLL2CRStatic(unittest.TestCase):
def test_lcc_basic1(self):
Expand All @@ -66,9 +77,32 @@ def test_lcc_basic1(self):
w = grid_info["width"]
h = grid_info["height"]
points_in_grid = _ll2cr.ll2cr_static(lon_arr, lat_arr, fill_in, proj_str,
cw, ch, w, h, ox, oy)
cw, ch, w, h, ox, oy)
self.assertEqual(points_in_grid, lon_arr.size, "all these test points should fall in this grid")

def test_geo_antimeridian(self):
""" Ensure output for anti-meridian crossing input includes all points. """
from pyresample.ewa import _ll2cr
lon_arr = create_test_longitude(160.0, 200.0, (50, 100), dtype=np.float64)
lat_arr = create_test_latitude(40.0, 60.0, (50, 100), dtype=np.float64)

# wrap values in lon_arr so -180 ≤ longitude (degrees east) ≤ 180
lon_arr[lon_arr > 180] -= 360.0

grid_info = static_geo_whole_earth.copy()
fill_in = np.nan
proj_str = grid_info['proj4_definition']
cw = grid_info['cell_width']
ch = grid_info['cell_height']
ox = grid_info['origin_x']
oy = grid_info['origin_y']
w = grid_info['width']
h = grid_info['height']
points_in_grid = _ll2cr.ll2cr_static(lon_arr, lat_arr, fill_in, proj_str,
cw, ch, w, h, ox, oy)
self.assertEqual(points_in_grid, lon_arr.size,
'all these test points should fall in this grid')

def test_lcc_fail1(self):
from pyresample.ewa import _ll2cr
lon_arr = create_test_longitude(-15.0, 15.0, (50, 100), dtype=np.float64)
Expand Down