Detect circles width vision framework on ios11?

Question

I need to detect circles in an image. iOS11 allows to detect and track rectangles but how can we track circles ?

Is it possible ?

Answer 1

I have not seen anything like CIRectangleFeature for circles. As a workaround you may use OpenCV framework that has a Hough Circle Transformation.

Pro: it's multi-platform compliant.

Con: you need to embed a large library for one feature.

Edit: I tried implementing an objc class VNDetectCirclesRequest : VNImageBasedRequest. Unfortunately, those classes have a private implementation and the program crashes with "-[VNDetectCirclesRequest internalPerformInContext:error:] has not been implemented". I have also tried to implement this method, but the parameter context is of type VNRequestPerformingContext that is private.

See OpenCV doc