找到一個圖像的輪廓質心

Question

我試圖計算圖像重心，像這樣：

// Calculate centroid 
    double signedArea = 0.0; 
    sskp_point centroid; 
    for(int i=0;i<numPoints;i++) 
    { 
     double a = (points[i].x*points[(i+1)%numPoints].y)-(points[(i+1)%numPoints].x*points[i].y); 
     signedArea += a; 
     centroid.x += (points[i].x*points[(i+1)%numPoints].x)*a; 
     centroid.y += (points[i].y*points[(i+1)%numPoints].y)*a; 
     printf("points[%d] = { %f, %f }\n",i,points[i].x,points[i].y); 
    } 
    signedArea /= 2.0; 
    centroid.x /= (6*signedArea); 
    centroid.y /= (6*signedArea); 
    printf("centroid = { %f, %f }\n",centroid.x,centroid.y); 

我從算法here適應這一點，但它給我的錯誤results，誰能告訴我是什麼這適應錯了嗎？

Answer 1

你已經寫centroid.x += (points[i].x*points[(i+1)%numPoints].x)*a; 相反，它應該是centroid.x += (points[i].x+points[(i+1)%numPoints].x)*a; 你有+我更換*。

Answer 2

我看了一下，你拿這個樣本的線程，我認爲你應該有 centroid.x + =（points [i] .x + points [（i + 1）％numPoints] .x）*一個; centroid.y + =（points [i] .y + points [（i + 1）％numPoints] .y）* a;