# OpticalFlowObservation An object that represents an optical flow that an image-analysis request produces. ``` struct OpticalFlowObservation ``` ## Overview The optical flow is a 2D image, with each pixel representing the directional change from a previous to current image. ## Topics ### Creating an observation [`init?(VNPixelBufferObservation)`](/documentation/Vision/OpticalFlowObservation/init(_:)) Creates an optical flow observation. ### Inspecting an observation [`var pixelFormat: OSType`](/documentation/Vision/OpticalFlowObservation/pixelFormat) The four-character code that identifies the pixel format. [`var pixelBuffer: CVReadOnlyPixelBuffer`](/documentation/Vision/OpticalFlowObservation/pixelBuffer) [`var size: CGSize`](/documentation/Vision/OpticalFlowObservation/size) The size of the observation image. ### Getting the optical flow [`func flow(at: NormalizedPoint) -> (Float, Float)`](/documentation/Vision/OpticalFlowObservation/flow(at:)) Returns the optical flow for the specified location in the observation image. ### Accessing the memory [`func withUnsafePointer((UnsafeRawPointer) -> R) -> R`](/documentation/Vision/OpticalFlowObservation/withUnsafePointer(_:)) Invokes the given closure with a pointer to the given argument. ## Relationships ### Conforms To [`Hashable`](/documentation/Swift/Hashable) [`Decodable`](/documentation/Swift/Decodable) [`Equatable`](/documentation/Swift/Equatable) [`SendableMetatype`](/documentation/Swift/SendableMetatype) [`Sendable`](/documentation/Swift/Sendable) [`Encodable`](/documentation/Swift/Encodable) [`CustomStringConvertible`](/documentation/Swift/CustomStringConvertible) [`VisionObservation`](/documentation/Vision/VisionObservation) --- Copyright © 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)