RandomGeoSampler: improve performance (#1968)

torchgeo/samplers/utils.py

@@ -56,17 +56,16 @@ def get_random_bounding_box(
     """
     t_size = _to_tuple(size)
 
-    width = (bounds.maxx - bounds.minx - t_size[1]) // res
-    height = (bounds.maxy - bounds.miny - t_size[0]) // res
+    # May be negative if bounding box is smaller than patch size
+    width = (bounds.maxx - bounds.minx - t_size[1]) / res
+    height = (bounds.maxy - bounds.miny - t_size[0]) / res
 
     minx = bounds.minx
     miny = bounds.miny
 
-    # random.randrange crashes for inputs <= 0
-    if width > 0:
-        minx += torch.rand(1).item() * width * res
-    if height > 0:
-        miny += torch.rand(1).item() * height * res
+    # Use an integer multiple of res to avoid resampling
+    minx += int(torch.rand(1).item() * width) * res
+    miny += int(torch.rand(1).item() * height) * res
 
     maxx = minx + t_size[1]
     maxy = miny + t_size[0]