<!--
{
  "availability" : [
    "iOS: 18.0.0 -",
    "iPadOS: 18.0.0 -",
    "macOS: 15.0.0 -",
    "tvOS: 18.0.0 -",
    "visionOS: 2.0.0 -",
    "watchOS: 27.0.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "Vision",
  "identifier" : "/documentation/Vision/TrajectoryObservation",
  "metadataVersion" : "0.1.0",
  "role" : "Structure",
  "symbol" : {
    "kind" : "Structure",
    "modules" : [
      "Vision"
    ],
    "preciseIdentifier" : "s:6Vision21TrajectoryObservationV"
  },
  "title" : "TrajectoryObservation"
}
-->

# TrajectoryObservation

An observation that describes a detected trajectory.

```
struct TrajectoryObservation
```

## Topics

### Creating an observation

[`init(VNTrajectoryObservation)`](/documentation/Vision/TrajectoryObservation/init(_:))

Creates a trajectory observation.

### Inspecting an observation

[`let detectedPoints: [NormalizedPoint]`](/documentation/Vision/TrajectoryObservation/detectedPoints)

The centroid points of the detected contour along the trajectory.

[`let projectedPoints: [NormalizedPoint]`](/documentation/Vision/TrajectoryObservation/projectedPoints)

The centroids of the calculated trajectory from the detected points.

[`let equationCoefficients: simd_float3`](/documentation/Vision/TrajectoryObservation/equationCoefficients)

The coefficients of the parabolic equation.

[`let movingAverageRadius: CGFloat`](/documentation/Vision/TrajectoryObservation/movingAverageRadius)

The moving average radius of the object the request is tracking.

## Relationships

### Conforms To

[`VisionObservation`](/documentation/Vision/VisionObservation)

[`Hashable`](/documentation/Swift/Hashable)

[`Equatable`](/documentation/Swift/Equatable)

[`Escapable`](/documentation/Swift/Escapable)

[`CustomStringConvertible`](/documentation/Swift/CustomStringConvertible)

[`Encodable`](/documentation/Swift/Encodable)

[`Decodable`](/documentation/Swift/Decodable)

[`SendableMetatype`](/documentation/Swift/SendableMetatype)

[`Copyable`](/documentation/Swift/Copyable)

[`Sendable`](/documentation/Swift/Sendable)

---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)