From 67403b0e96226a1a1ab24bd635e8fe5b3d04acbb Mon Sep 17 00:00:00 2001
From: John Lambert <johnlambert@gatech.edu>
Date: Sat, 21 Aug 2021 21:08:37 -0600
Subject: [PATCH] clean up SFMdata

---
 python/gtsam/examples/SFMdata.py | 33 +++++++++++++++++---------------
 1 file changed, 18 insertions(+), 15 deletions(-)

diff --git a/python/gtsam/examples/SFMdata.py b/python/gtsam/examples/SFMdata.py
index 6ac9c5726..ad414a256 100644
--- a/python/gtsam/examples/SFMdata.py
+++ b/python/gtsam/examples/SFMdata.py
@@ -5,36 +5,39 @@ A structure-from-motion example with landmarks
 """
 # pylint: disable=invalid-name, E1101
 
+from typing import List
+
 import numpy as np
 
 import gtsam
+from gtsam import Cal3_S2, Point3, Pose3
 
 
-def createPoints():
+def createPoints() -> List[Point3]:
     # Create the set of ground-truth landmarks
-    points = [gtsam.Point3(10.0, 10.0, 10.0),
-              gtsam.Point3(-10.0, 10.0, 10.0),
-              gtsam.Point3(-10.0, -10.0, 10.0),
-              gtsam.Point3(10.0, -10.0, 10.0),
-              gtsam.Point3(10.0, 10.0, -10.0),
-              gtsam.Point3(-10.0, 10.0, -10.0),
-              gtsam.Point3(-10.0, -10.0, -10.0),
-              gtsam.Point3(10.0, -10.0, -10.0)]
+    points = [
+        Point3(10.0, 10.0, 10.0),
+        Point3(-10.0, 10.0, 10.0),
+        Point3(-10.0, -10.0, 10.0),
+        Point3(10.0, -10.0, 10.0),
+        Point3(10.0, 10.0, -10.0),
+        Point3(-10.0, 10.0, -10.0),
+        Point3(-10.0, -10.0, -10.0),
+        Point3(10.0, -10.0, -10.0),
+    ]
     return points
 
 
-def createPoses(K):
-    # Create the set of ground-truth poses
+def createPoses(K: Cal3_S2) -> List[Pose3]:
+    """Generate a set of ground-truth camera poses arranged in a circle about the origin."""
     radius = 40.0
     height = 10.0
-    angles = np.linspace(0, 2*np.pi, 8, endpoint=False)
+    angles = np.linspace(0, 2 * np.pi, 8, endpoint=False)
     up = gtsam.Point3(0, 0, 1)
     target = gtsam.Point3(0, 0, 0)
     poses = []
     for theta in angles:
-        position = gtsam.Point3(radius*np.cos(theta),
-                                radius*np.sin(theta),
-                                height)
+        position = gtsam.Point3(radius * np.cos(theta), radius * np.sin(theta), height)
         camera = gtsam.PinholeCameraCal3_S2.Lookat(position, target, up, K)
         poses.append(camera.pose())
     return poses