Update spatial-analysis-operations.md

Author: Juliako

articles/azure-video-analyzer/video-analyzer-docs/spatial-analysis-operations.md

@@ -34,7 +34,7 @@ See an example of [Person Zone Crossing Operation](https://raw.githubusercontent
 | ------------------------- | ------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | `zones`                     | list    | List of zones.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
 | `name`                     | string  | Friendly name for this zone.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
-| `polygon`                   | string  | Each value pair represents the x,y for vertices of polygon. The polygon represents the areas in which people are tracked or counted. The float values represent the position of the vertex relative to the top-left corner. To calculate the absolute x, y values, you multiply these values with the frame size. threshold float Events are egressed when the person is greater than this number of pixels inside the zone. The default value is 48 when type is `zonecrossing` and 16 when time is `DwellTime`. These are the recommended values to achieve maximum accuracy. |
+| `polygon`                   | string  | Each value pair represents the x,y for vertices of polygon. The polygon represents the areas in which people are tracked or counted. The float values represent the position of the vertex relative to the top-left corner. To calculate the absolute x, y values, you multiply these values with the frame size. `threshold` float events are egressed when the person is greater than this number of pixels inside the zone. The default value is 48 when type is `zonecrossing` and 16 when time is `DwellTime`. These are the recommended values to achieve maximum accuracy. |
 | `eventType`                 | string  | For cognitiveservices.vision.spatialanalysis-personcrossingpolygon this should be `zonecrossing` or `zonedwelltime`.                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
 | `trigger`                   | string  | The type of trigger for sending an event. Supported Values: "event": fire when someone enters or exits the zone.                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
 | `focus`                     | string  | The point location within person's bounding box used to calculate events. Focus's value can be footprint (the footprint of person), bottom_center (the bottom center of person's bounding box), center (the center of person's bounding box). The default value is footprint.                                                                                                                                                                                                                                                                                               |