如何在決策條件下使用Object Detection Bounding Box來使用C++ OpenCV打開Raspberry Pi上的LED？

Question

我正在使用OpenCV 2.4.8創建一個應用程序，它將檢測槍。該應用程序將部署在Raspberry Pi上。 LED /蜂鳴器也連接到樹莓派。如果檢測到槍，應根據某些特定條件打開LED /蜂鳴器。我附上了相關的代碼。問題是，如何判斷槍是否被檢測到？我的意思是，檢測到的槍由邊界框顯示。現在，如何在IF-Condition中使用邊界框？我已經在代碼中註釋了所需的行，就像我想要的那樣。任何人都可以請指導我如何做到這一點？任何幫助，高度讚賞！謝謝。
這裏是我的代碼片段：

for(;;) 
{ 
    cap.retrieve(frame); 
    cap >> frame; 
std::vector<Rect> guns; 
Mat frame_gray; 

cvtColor(frame, frame_gray, COLOR_BGR2GRAY); 
equalizeHist(frame_gray, frame_gray); 

// Detect guns 
gun_cascade.detectMultiScale(frame_gray, guns, 1.1, 2, 0 | CASCADE_SCALE_IMAGE, Size(30 , 30)); 

// Set Region of Interest 
cv::Rect roi_b; 
cv::Rect roi_c; 
cv::Rect bbox; 
size_t ic = 0; // ic is index of current element 
int ac = 0; // ac is area of current element 

size_t ib = 0; // ib is index of biggest element 
int ab = 0; // ab is area of biggest element 

for (ic = 0; ic < guns.size(); ic++) // Iterate through all current elements (detected guns) 

{ 
    roi_c.x = guns[ic].x; 
    roi_c.y = guns[ic].y; 
    roi_c.width = (guns[ic].width); 
    roi_c.height = (guns[ic].height); 

    ac = roi_c.width * roi_c.height; // Get the area of current element (detected gun) 

    roi_b.x = guns[ib].x; 
    roi_b.y = guns[ib].y; 
    roi_b.width = (guns[ib].width); 
    roi_b.height = (guns[ib].height); 

    ab = roi_b.width * roi_b.height; // Get the area of biggest element, at beginning it is same as "current" element 

    if (ac > ab) 
    { 
     ib = ic; 
     roi_b.x = guns[ib].x; 
     roi_b.y = guns[ib].y; 
     roi_b.width = (guns[ib].width); 
     roi_b.height = (guns[ib].height); 
    } 

    Point pt1(guns[ic].x, guns[ic].y); // Display detected guns on main window - live stream from camera 
    Point pt2((guns[ic].x + guns[ic].height), (guns[ic].y + guns[ic].width)); 

    //bbox = cvRect(roi_b.x, roi_b.y, roi_b.width, roi_b.height); 
    //int counter = 0; 

    rectangle(frame, pt1, pt2, Scalar(0, 0, 255), 2, 8, 0); 
    putText(frame, "Gun Detected!", pt1, FONT_HERSHEY_COMPLEX_SMALL, 0.8, cvScalar(0,250,250), 1, CV_AA); 


    // if(gun detected) 
    //counter = counter + 1; 
    /* 
    if(counter > 5) 
    { 
     turn on the LED of Raspberry Pi; 
     counter = 0; 
    } 
    */ 

} //end of inner for loop 

imshow("original", frame); 
if(waitKey(30) >= 0) break; 
} //end of outer for loop 
return 0; 
} //end main 

Answer 1

你有很多可以放倒，以單行語句明確的代碼。

ab = 0; 
for(ic=0; ic < guns.size(); ic++) 
{ 
    roi_c = guns[i]; 
    if(roi_c.area() > ab) 
    { 
     roi_b = roi_c; 
     ab = roi_c.area(); 
    } 

    rectangle(frame, roi_c, Scalar(0, 0, 255), 2, 8, 0); 
} 

如果您要檢查，如果檢測至少一支槍，你可以寫：if(guns.size() > 0) { .. }。如果你想檢查檢測到的最大槍是否大於某個閾值，你可以使用類似if(roi_b.area() > some_threshold)的東西。

希望這個答案。