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# VNGenerateOpticalFlowRequest

An object that generates directional change vectors for each pixel in the targeted image.

```
class VNGenerateOpticalFlowRequest
```

## Overview

This request operates at a pixel level, so both images need to have the same dimensions to successfully perform the analysis. Setting a region of interest limits the region in which the analysis occurs. However, the system reports the resulting observation at full resolution.

Optical flow requests are resource-intensive, so create only one request at a time, and release it immediately after generating optical flows.

## Topics

### Configuring the Request

[`computationAccuracy`](/documentation/Vision/VNGenerateOpticalFlowRequest/computationAccuracy-swift.property)

The accuracy level for computing optical flow.

[`VNGenerateOpticalFlowRequest.ComputationAccuracy`](/documentation/Vision/VNGenerateOpticalFlowRequest/ComputationAccuracy-swift.enum)

The supported optical flow accuracy levels.

[`outputPixelFormat`](/documentation/Vision/VNGenerateOpticalFlowRequest/outputPixelFormat)

The output buffer’s pixel format.

[`keepNetworkOutput`](/documentation/Vision/VNGenerateOpticalFlowRequest/keepNetworkOutput)

A Boolean value that indicates whether to keep the raw pixel buffer coming from the machine learning network.

### Accessing the Results

[`results`](/documentation/Vision/VNGenerateOpticalFlowRequest/results)

The results of the request to generate optical flow.

### Identifying Request Revisions

[`VNGenerateOpticalFlowRequestRevision2`](/documentation/Vision/VNGenerateOpticalFlowRequestRevision2)

A constant for specifying revision 2 of the optical flow generation request.

[`VNGenerateOpticalFlowRequestRevision1`](/documentation/Vision/VNGenerateOpticalFlowRequestRevision1)

A constant for specifying revision 1 of the optical flow generation request.


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