OpenCV Face Detection - vector issue

Question

I'm using the following code to perform face detection using OpenCV on the iPhone.

std::vector<Rect> faces;

face_cascade.detectMultiScale( frame_gray, faces, 1.1, 2, 0|CV_HAAR_SCALE_IMAGE, cv::Size(15, 15) );

However, when I try to build the app, an error is thrown at the detectMultiScale function call. "No matching member function call to 'detectMultiScale'".

The following further explanation is given:

The errors read: Candidate function not viable: no known conversion from 'std::vector<Rect>' to 'vector<Rect> &' for 2nd argument.

What is going on here? Evidently the compiler takes issue with the second argument. Am I using a different type of vector?

Thanks, James

XCode 4.2.1 SDK 5.0 OpenCV 2.

Answer 1

You have to add

using namespace cv; 

at the beginning.