Raster imports: handle north-oriented file orders

This boils down to south-oriented files needing to be shifted down half a basedata cell while south oriented files are shifted up. Updates #845
shawnlaffan · Jan 31, 2023 · 18f22df · 18f22df
1 parent 7cd3027
commit 18f22df
Showing 1 changed file with 5 additions and 3 deletions.
diff --git a/lib/Biodiverse/BaseData/Import.pm b/lib/Biodiverse/BaseData/Import.pm
@@ -740,6 +740,9 @@ sub import_data_raster {
         #  that it should since Biodiverse doesn't either.
         $cellsize_e ||= abs $tf_1;
         $cellsize_n ||= abs $tf_5;
+        if ($tf_5 < 0) {  #  shift down south-oriented files
+            $halfcellsize_n = -(abs $halfcellsize_n);
+        }
 
         # iterate over each band
         foreach my $band_id ( 1 .. $band_count ) {
@@ -835,7 +838,7 @@ sub import_data_raster {
                               floor( ( $ngeo - $cellorigin_n ) / $cellsize_n );
                             $grpn =
                               $cellorigin_n +
-                              $ncell * $cellsize_n -
+                              $ncell * $cellsize_n +
                               $halfcellsize_n;
                         }
 
@@ -878,10 +881,9 @@ sub import_data_raster {
                                 $ngeo = $tf_3 + $gridx * $tf_4 + $gridy * $tf_5;
                                 $ncell = floor( ( $ngeo - $cellorigin_n ) / $cellsize_n );
 
-                                # subtract half cell width since position is top-left
                                 $grpn =
                                   $cellorigin_n +
-                                  $ncell * $cellsize_n -
+                                  $ncell * $cellsize_n +
                                   $halfcellsize_n;
 
                                 #  cannot guarantee constant groups