Dnn NetReadFromDarknet model function error

C++
1

When call function forward of a model NetReadFromDarknet, only work if i call using this format:

blob = blobFromImage(image, 0.00392, Size(416, 416), Scalar(0, 0, 0),true, false);
model.setInput(blob);
Mat outMat;
outMat = model.forward();

But if i call using a vector of strings names as parameters:

        model.setInput(blob);
        Mat outMat;
        model.forward(outMat, names);

Give me back this:
terminate called after throwing an instance of ‘cv::Exception’
what(): OpenCV(4.5.5-dev) /opt/opencv/modules/core/src/matrix_wrap.cpp:2052: error: (-213:The function/feature is not implemented) in function ‘assign’

All code:

#include <opencv4/opencv2/opencv.hpp>
#include <opencv4/opencv2/core/ocl.hpp>

#include <opencv4/opencv2/dnn.hpp>
#include <opencv4/opencv2/dnn/all_layers.hpp>

#include <X11/Xlib.h>
#include <X11/Xutil.h>

#include <time.h>
using namespace cv;
using namespace std;
using namespace dnn;

int main()
{

    cv::ocl::Context context;
    cv::ocl::Device(context.device(1));

    ScreenShot screen(0, 0, 1024, 768);

    Mat image, blob;
    UMat UImg, Ublob;
    

    std::vector<std::string> class_names {"sign_red", "sign_green", "sign_yellow"};
    auto model = readNetFromDarknet("cfg.cfg", "weights/peso.weights");

    model.setPreferableBackend(cv::dnn::DNN_BACKEND_OPENCV);
    model.setPreferableTarget(DNN_TARGET_OPENCL);

    while(true) 
    {
        screen(image);

        cvtColor(image, image, COLOR_BGRA2BGR);

        int image_height = image.cols;
        int image_width = image.rows;

        auto start = getTickCount();
        
        blob = blobFromImage(image, 0.00392, Size(416, 416), Scalar(0, 0, 0),true, false);
        
        model.setInput(blob,"", 0.00392, 0);
    
        vector<int> outLayers = model.getUnconnectedOutLayers();
        vector<cv::String> layersNames = model.getLayerNames();
        
        vector<cv::String> names;
        names.resize(outLayers.size());

        Mat outMat;
        model.forward(outMat, names); // the error is called here
        ...
    }
}

How could I solve this? Thank you!

2

since yolo networks have several (2 or 3) outputs, you need a vector<Mat> to capture the results.
you also need to make sure, your names contain something meaningful !

all in all, use:

vector<Mat> outputs;
vector<string> names = model.getUnconnectedOutLayersNames();

model.forward(outputs, names);
4

Im receiving same error, already try this and a lot things…

terminate called after throwing an instance of 'cv::Exception'
  what():  OpenCV(4.5.5-dev) /opt/opencv/modules/core/src/matrix_wrap.cpp:2052: error: (-213:The function/feature is not implemented)  in function 'assign'

In my research another users pass through this problem, but anyone solve this with a reply. Thank you!