编译CV_MAT_ELEM中的错误 [英] Compile error in CV_MAT_ELEM
问题描述
由于调用estimateRigidTransform(),我得到一个名为trans的cv :: Mat对象。要检索其包含的矩阵,我尝试以这种方式访问其元素:
for(i = 0; i <2; i ++) for(j = 0; j <3; j ++)
{
mtx [j] [i] = CV_MAT_ELEM(trans,double,i,j)不幸的是在VS2010我收到一个编译错误
错误C2228:'.ptr'的左侧必须有类/ struct / union
用于具有CV_MAT_ELEM的行。当我解开这个宏我发现像
(mat).data.ptr +(size_t)(mat).step *当我删除后面的.ptr时,会出现这样的情况:(a)(b)(b)(b)(b) (mat).data它编译。但我不能想象这是解决方案(或者不能想象这是一个错误,我是唯一一个注意到它)。 解决方案你不能像这样访问垫元素。对于遍历,请参阅我的其他答案与示例代码:
color matrix遍历
或查看opencv refman的灰度Mat:
Mat M; // should be grayscale
int cols = M.cols,rows = M.rows;
for(int i = 0; i< rows; i ++)
{
const double * Mi = M.ptr double(i);
for(int j = 0; j< cols; j ++)
{
Mi [j]; //是矩阵元素。
}
}
As a result of a call to estimateRigidTransform() I get a cv::Mat object named "trans". To retrieve its contained matrix I try to access its elements this way:
for (i=0; i<2; i++) for (j=0; j<3; j++)
{
mtx[j][i]=CV_MAT_ELEM(trans,double,i,j);
}
Unfortunately with VS2010 I get a compiler error
error C2228: left of '.ptr' must have class/struct/union
for the line with CV_MAT_ELEM. When I unwrap this macro I find something like
(mat).data.ptr + (size_t)(mat).step*(row) + (pix_size)*(col))
When I remove the ".ptr" behind (mat).data it compiles. But I can't imagine that's the solution (or can't imagine that's a bug and I'm the only one who noticed it). So what could be wrong here really?
Thanks!
解决方案 You don't access the mat elements like this. For a traversal see my other answer here with sample code:
color matrix traversal
or see the opencv refman for grayscale Mat:
Mat M; // should be grayscale
int cols = M.cols, rows = M.rows;
for(int i = 0; i < rows; i++)
{
const double* Mi = M.ptr<double>(i);
for(int j = 0; j < cols; j++)
{
Mi[j]; // is the matrix element.
}
}
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