CODEWITHSUNDEEP
iosswiftmachine-learningface-detectionapple-vision
Pasow
Pasow

Reputation: 1

Vision Framework (iOS): How are VNDetectFaceLandmarksRequest and VNDetectFaceRectanglesRequest different?

There are two different requests that you can use for face detection tasks with the iOS Vision Framework: VNDetectFaceLandmarksRequest and VNDetectFaceRectanglesRequest. Both of them return an array of VNFaceObservation, one for each detected face. VNFaceObservation has a variety of optional properties, including boundingBox and landmarks. The landmarks object then also includes optional properties like nose, innerLips, leftEye, etc.

Do the two different Vision requests differ in how they perform face detection?

It seems that VNDetectFaceRectanglesRequest only finds a bounding box (and maybe some other properties), but does not find any landmarks. On the other hand, VNDetectFaceLandmarksRequest seems to find both, bounding box and landmarks. Are there cases where one request type will find a face and the other one will not? Is VNDetectFaceLandmarksRequest superior to VNDetectFaceRectanglesRequest, or does the latter maybe have advantages in performance or reliability?

Here is an example code of how these two Vision requests can be used:

let faceLandmarkRequest = VNDetectFaceLandmarksRequest()
let faceRectangleRequest = VNDetectFaceRectanglesRequest()
let requestHandler = VNImageRequestHandler(ciImage: image, options: [:])
try requestHandler.perform([faceRectangleRequest, faceLandmarkRequest])
if let rectangleResults = faceRectangleRequest.results as? [VNFaceObservation] {
    let boundingBox1 = rectangleResults.first?.boundingBox   //this is an optional type
}
if let landmarkResults = faceLandmarkRequest.results as? [VNFaceObservation] {
    let boundingBox2 = landmarkResults.first?.boundingBox   //this is an optional type
    let landmarks = landmarkResults.first?.landmarks   //this is an optional type
}

Upvotes: 0

Views: 1526

Answers (1)

Maksim Chizhavko
Maksim Chizhavko

Reputation: 21

  • VNDetectFaceRectanglesRequest is a more lightweight operation for finding face rectangle
  • VNDetectFaceLandmarksRequest is a heavier operation, which can also help locate landmarks on the face

Upvotes: 2

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