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POOpenCV matrix multiplication with unknown number type
 

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  1. POOpenCV matrix multiplication with unknown number type
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    <p>I'm having some processing i.e. some matrix operations using Mat in OpenCV and the following line gives error:</p> <pre><code>matC = matA*matB; </code></pre> <p>This time, the error is not that difficult to identify since I've already known that the matrix dimensions are correct and their number types are either CV_64FC1 or CV_32FC1. </p> <p>So, I can fix this error by identifying each matrix's number type (perhaps with some if-else) and replace with a temporary matrix (Mat) that is type compatible</p> <p>However, in terms of the implementation of OpenCV Mat multiplication, is it a good one? Do we really have to check the operands' number type (and even number of channel e.g. CV_64FC3, CV_64FC2) every time a matrix operation is performed?</p> <p>is this type of checking barely avoided? since matA or matB are probably returned from a function call such as solvePnP(..., matA, matB,...) and number type of matA, matB are undefined</p> <p>Thanks, </p> <p>PS: I've stuck with OpenCV matrix operation several times, problems with number type, number of channels...</p> <p>Edit 01:</p> <p>I'm sorry for not being clear in my question! but I'm doing my best to make myself clear</p> <p>my questions are:</p> <p>1) should I and how would I do to ensure matC = matA*matB is a error-free operation?</p> <p>2) in case there should be some checking before the operation, then, should I do that every time such matrix operation is performed? is there a better choice to not replicate such checking?</p> <p>Edit 02: </p> <p>here is what I currently do to perform the checking:</p> <pre><code>tmp1 = Vect32Homo(Mat(objPoints.at&lt;Vec3f&gt;(i))); if (s1To.depth() != tmp1.depth()) { printf("Different Number Type!"); s1To.convertTo(s1To, CV_64FC1); tmp1.convertTo(tmp1, CV_64FC1); } else { printf("Same Number Type!"); } tmp = s1To*tmp1; // error prone operation </code></pre> <p>As you may see that this attempt will not work if the two matrices have different number of channel</p>
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    1. PTQuestion
    1. USShawn Le
    1. USShawn Le
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    1. COSorry, I'm not intending to be rude, but I've read your question several times and I still don't understand what you're asking. Is it just that you are questioning the design decisions of OpenCV? If so, that's off-topic here and likely to result in the question being closed. Perhaps you could edit your question to clarify.
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      1. POOpenCV matrix multiplication with unknown number type
      1. USRoger Rowland
    2. COTry reshaping them to a single channel matrix, operations on matrix aren't well defined for multi-color arrays. There is a reshape() function that simply changes the header withotu copyign data
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      1. POOpenCV matrix multiplication with unknown number type
      1. USMartin Beckett
    3. CO@Beckett: how about number type difference? are you suggesting that I should unify their channel and number type using reshape before doing matrix operations? I'm not sure that is your advice
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      1. POOpenCV matrix multiplication with unknown number type
      1. USShawn Le
 

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