diff --git a/lib/xmet/geo.py b/lib/xmet/geo.py
index 221a1d4..3949c3f 100644
--- a/lib/xmet/geo.py
+++ b/lib/xmet/geo.py
@@ -1,4 +1,5 @@
 import re
+import math
 import shapely
 
 def load_poly_from_file(path: str) -> shapely.Polygon:
@@ -16,3 +17,9 @@ def load_poly_from_file(path: str) -> shapely.Polygon:
             points.append((float(lon), float(lat)))
 
     return shapely.Polygon(points)
+
+def line_heading(p1: shapely.Point, p2: shapely.Point) -> float:
+    dx = p2.x - p1.x
+    dy = p2.y - p1.y
+
+    return math.atan2(dy, dx)