Fix interpolation error

CHANGELOG.md

@@ -89,6 +89,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Annotations aren't updated after reopening a task (<https://github.com/opencv/cvat/pull/1753>)
 - Labels aren't updated after reopening a task (<https://github.com/opencv/cvat/pull/1753>)
 - Canvas isn't fitted after collapsing side panel in attribute annotation mode (<https://github.com/opencv/cvat/pull/1753>)
+- Error when interpolating polygons (<https://github.com/opencv/cvat/pull/1878>)
 
 ### Security
 - SQL injection in Django `CVE-2020-9402` (<https://github.com/opencv/cvat/pull/1657>)

cvat/apps/dataset_manager/annotation.py

@@ -442,11 +442,11 @@ def normalize_shape(shape):
 
     @staticmethod
     def get_interpolated_shapes(track, start_frame, end_frame):
-        def copy_shape(source, frame, points = None):
+        def copy_shape(source, frame, points=None):
             copied = deepcopy(source)
             copied["keyframe"] = True
             copied["frame"] = frame
-            if points:
+            if points is not None:
                 copied["points"] = points
             return copied
 

cvat/apps/dataset_manager/tests/test_annotation.py

@@ -8,7 +8,7 @@
 
 
 class TrackManagerTest(TestCase):
-    def test_single_point_interpolation(self):
+    def test_point_interpolation(self):
         track = {
             "frame": 0,
             "label_id": 0,
@@ -36,4 +36,94 @@ def test_single_point_interpolation(self):
 
         interpolated = TrackManager.get_interpolated_shapes(track, 0, 2)
 
+        self.assertEqual(len(interpolated), 3)
+
+    def test_polygon_interpolation(self):
+        track = {
+            "frame": 0,
+            "label_id": 0,
+            "group": None,
+            "attributes": [],
+            "shapes": [
+                {
+                    "frame": 0,
+                    "points": [1.0, 2.0, 3.0, 4.0, 5.0, 2.0],
+                    "type": "polygon",
+                    "occluded": False,
+                    "outside": False,
+                    "attributes": []
+                },
+                {
+                    "frame": 2,
+                    "attributes": [],
+                    "points": [3.0, 4.0, 5.0, 6.0, 7.0, 6.0, 4.0, 5.0],
+                    "type": "polygon",
+                    "occluded": False,
+                    "outside": True
+                },
+            ]
+        }
+
+        interpolated = TrackManager.get_interpolated_shapes(track, 0, 2)
+
+        self.assertEqual(len(interpolated), 3)
+
+    def test_bbox_interpolation(self):
+        track = {
+            "frame": 0,
+            "label_id": 0,
+            "group": None,
+            "attributes": [],
+            "shapes": [
+                {
+                    "frame": 0,
+                    "points": [1.0, 2.0, 3.0, 4.0],
+                    "type": "rectangle",
+                    "occluded": False,
+                    "outside": False,
+                    "attributes": []
+                },
+                {
+                    "frame": 2,
+                    "attributes": [],
+                    "points": [3.0, 4.0, 5.0, 6.0],
+                    "type": "rectangle",
+                    "occluded": False,
+                    "outside": True
+                },
+            ]
+        }
+
+        interpolated = TrackManager.get_interpolated_shapes(track, 0, 2)
+
+        self.assertEqual(len(interpolated), 3)
+
+    def test_line_interpolation(self):
+        track = {
+            "frame": 0,
+            "label_id": 0,
+            "group": None,
+            "attributes": [],
+            "shapes": [
+                {
+                    "frame": 0,
+                    "points": [1.0, 2.0, 3.0, 4.0, 5.0, 6.0],
+                    "type": "polyline",
+                    "occluded": False,
+                    "outside": False,
+                    "attributes": []
+                },
+                {
+                    "frame": 2,
+                    "attributes": [],
+                    "points": [3.0, 4.0, 5.0, 6.0],
+                    "type": "polyline",
+                    "occluded": False,
+                    "outside": True
+                },
+            ]
+        }
+
+        interpolated = TrackManager.get_interpolated_shapes(track, 0, 2)
+
         self.assertEqual(len(interpolated), 3)