Fix.

Signed-off-by: Daniel Scheffler <danschef@gfz-potsdam.de>

gms_preprocessing/algorithms/classification.py

@@ -422,7 +422,7 @@ class kNN_SAM_Classifier(SAM_Classifier):
     def label_unclassified_pixels(self, label_unclassified, threshold):
         # type: (int, Union[str, int, float]) -> GeoArray
         cmap_labelled0 = self._label_unclassified_pixels(
-            self.cmap[:, :, 0], label_unclassified, threshold, self.angles_deg[:, :, 0]
+            self.cmap.get_subset(zslice=slice(None, 1)), label_unclassified, threshold, self.angles_deg[:, :, 0]
         )
         cmap = self.cmap
         cmap[cmap_labelled0 == label_unclassified] = label_unclassified