Ability to configure min frames for zone presence (#6680)

* Objects need to be in zones multiple times to be considered present in the zone

* Add a field to configure inertia per zone

* Formatting

* Use correct default method

* Clarify zone presence behavior

Co-authored-by: Blake Blackshear <blakeb@blakeshome.com>

---------

Co-authored-by: Blake Blackshear <blakeb@blakeshome.com>

docs/docs/configuration/index.md

@@ -467,6 +467,8 @@ cameras:
         # Required: List of x,y coordinates to define the polygon of the zone.
         # NOTE: Presence in a zone is evaluated only based on the bottom center of the objects bounding box.
         coordinates: 545,1077,747,939,788,805
+        # Optional: Number of consecutive frames required for object to be considered present in the zone. Allowed values are 1-10 (default: shown below)
+        inertia: 3
         # Optional: List of objects that can trigger this zone (default: all tracked objects)
         objects:
           - person

frigate/config.py

@@ -330,6 +330,12 @@ class ZoneConfig(BaseModel):
     coordinates: Union[str, List[str]] = Field(
         title="Coordinates polygon for the defined zone."
     )
+    inertia: int = Field(
+        default=3,
+        title="Number of consecutive frames required for object to be considered present in the zone.",
+        gt=0,
+        le=10,
+    )
     objects: List[str] = Field(
         default_factory=list,
         title="List of objects that can trigger the zone.",

frigate/object_processing.py

@@ -73,6 +73,7 @@ class TrackedObject:
         self.colormap = colormap
         self.camera_config = camera_config
         self.frame_cache = frame_cache
+        self.zone_presence = {}
         self.current_zones = []
         self.entered_zones = []
         self.false_positive = True
@@ -144,13 +145,24 @@ class TrackedObject:
             if len(zone.objects) > 0 and obj_data["label"] not in zone.objects:
                 continue
             contour = zone.contour
+            zone_score = self.zone_presence.get(name, 0)
             # check if the object is in the zone
             if cv2.pointPolygonTest(contour, bottom_center, False) >= 0:
+                self.zone_presence[name] = zone_score + 1
+
+                # an object is only considered present in a zone if it has a zone inertia of 3+
+                if zone_score >= zone.inertia:
                     # if the object passed the filters once, dont apply again
-                if name in self.current_zones or not zone_filtered(self, zone.filters):
+                    if name in self.current_zones or not zone_filtered(
+                        self, zone.filters
+                    ):
                         current_zones.append(name)
                         if name not in self.entered_zones:
                             self.entered_zones.append(name)
+            else:
+                # once an object has a zone inertia of 3+ it is not checked anymore
+                if 0 < zone_score < zone.inertia:
+                    self.zone_presence[name] = zone_score - 1
 
         if not self.false_positive:
             # if the zones changed, signal an update