如何正确检查H矩阵的有效性

Question

我正在使用SIFT算法进行图像匹配，并且我计算单应矩阵以了解对象与场景之间是否存在有效对应关系。方法＆＃34; isValidHMatrix＆＃34;下面发表的是我如何检查H矩阵是否良好，如发布in this question，我计算H矩阵中左上角2x2矩阵的行列式，如果行列式是> = 0那么它是其他好的H矩阵很糟糕。

但是当我应用这个概念来找到某些物体和场景之间的匹配时，我得到了下面发布的结果作为图像：

请让我知道如何正确检查H矩阵的有效性

结果：

for image 1: the object is part of the scene, but i got "invalid HMatrix,   
det(H): -8.978588811689873" 

for image 2: the object is not part of the scene, but i got "valid HMatrix, 
det(H): 3.32362768456779" 

for image 3: the object is not part of the scene, but i got 
"goodMatchesList.size() < 4 points" 

for image 4: the object is part of the scene, but i got "valid HMatrix, 
det(H): 0.153917265625088" 

for image 5: the object is part of the scene, but i got "valid HMatrix, 
det(H): 1.0012971075010808" 

for image 6: the object is part of the scene, but i got "valid HMatrix, 
det(H): 0.0037162733516824488" 

for image 7: the object is not part of the scene, but i got "invalid 
HMatrix, det(H): -2.397038481177457E-6" 

for image 8: the object is not part of the scene, but i got "valid HMatrix, 
det(H): 0.0" 

码：

private boolean isValidHMatrix(Mat hMatrix, String token) {
    // TODO Auto-generated method stub
    //double det = Core.determinant(hMatrix);
    double det = Core.determinant(hMatrix.submat(new Rect (new Point(0, 0), new Point(2, 2))));

    if (det >= 0) {
        Log.V(TAG, "isValidHMatrix", token+"_valid HMatrix, det(H): "+det);
        return true;
    } else {
        Log.V(TAG, "isValidHMatrix", token+"_invalid HMatrix, det(H): "+det);
        return false;
    }

}