Fix EWA resampling when input data is larger than the output area

pyresample/ewa/_fornav_templates.cpp

@@ -245,7 +245,7 @@ int compute_ewa(size_t chan_count, int maximum_weight_mode,
       u0 = uimg[swath_offset];
       v0 = vimg[swath_offset];
 
-      if (u0 < 0.0 || v0 < 0.0 || __isnan(u0) || __isnan(v0)) {
+      if (u0 < -this_ewap->u_del || v0 < -this_ewap->v_del || __isnan(u0) || __isnan(v0)) {
         continue;
       }
 
@@ -352,15 +352,14 @@ int compute_ewa_single(int maximum_weight_mode,
   IMAGE_TYPE this_val;
   unsigned int swath_offset;
   unsigned int grid_offset;
-  size_t chan;
 
   got_point = 0;
   for (row = 0, swath_offset=0; row < swath_rows; row+=1) {
     for (col = 0, this_ewap = ewap; col < swath_cols; col++, this_ewap++, swath_offset++) {
       u0 = uimg[swath_offset];
       v0 = vimg[swath_offset];
 
-      if (u0 < 0.0 || v0 < 0.0 || __isnan(u0) || __isnan(v0)) {
+      if (u0 < -this_ewap->u_del || v0 < -this_ewap->v_del || __isnan(u0) || __isnan(v0)) {
         continue;
       }
 

pyresample/ewa/dask_ewa.py

@@ -351,8 +351,8 @@ def _run_fornav_single(self, data, out_chunks, target_geo_def, fill_value, **kwa
         ll2cr_blocks = self.cache['ll2cr_blocks'].items()
         ll2cr_numblocks = ll2cr_result.shape if isinstance(ll2cr_result, np.ndarray) else ll2cr_result.numblocks
         fornav_task_name = "fornav-{}".format(data.name)
-        maximum_weight_mode = kwargs.get('maximum_weight_mode', False)
-        weight_sum_min = kwargs.get('weight_sum_min', -1.0)
+        maximum_weight_mode = kwargs.setdefault('maximum_weight_mode', False)
+        weight_sum_min = kwargs.setdefault('weight_sum_min', -1.0)
         output_stack = self._generate_fornav_dask_tasks(out_chunks,
                                                         ll2cr_blocks,
                                                         fornav_task_name,

pyresample/test/test_ewa_fornav.py

@@ -54,6 +54,28 @@ def test_fornav_swath_larger(self):
         self.assertTrue(((out == 1) | np.isnan(out)).all(),
                         msg="Unexpected interpolation values were returned")
 
+    def test_fornav_swath_wide_input(self):
+        """Test that a swath with large input pixels on the left edge of the output."""
+        from pyresample.ewa import _fornav
+        swath_shape = (400, 800)
+        data_type = np.float32
+        # Create a fake row and cols array
+        rows = np.empty(swath_shape, dtype=np.float32)
+        rows[:] = np.linspace(-500, 500, 400)[:, None]
+        cols = np.empty(swath_shape, dtype=np.float32)
+        cols[:] = np.linspace(-500, 500, 800) + 0.5
+        rows_per_scan = 16
+        # Create a fake data swath
+        data = np.ones(swath_shape, dtype=data_type)
+        out = np.empty((800, 1000), dtype=data_type)
+
+        grid_points_covered = _fornav.fornav_wrapper(cols, rows, (data,), (out,),
+                                                     np.nan, np.nan, rows_per_scan)
+        one_grid_points_covered = grid_points_covered[0]
+        # the upper-left 500x500 square should be filled with 1s at least
+        assert 500 * 500 <= one_grid_points_covered <= 505 * 505
+        np.testing.assert_allclose(out[:500, :500], 1)
+
     def test_fornav_swath_smaller(self):
         """Test that a swath smaller than the output grid is entirely used."""
         from pyresample.ewa import _fornav