CODEWITHSUNDEEP
c++qtopencvvector
ner
ner

Reputation: 711

How do I declare a vector in OpenCV?

How do you write a vector in OpenCV? that contains 3 values like this v = [p1,p2,p3]? This is what I tried:

int dim [1] = {3};
Mat v(1,dim,CV_32F, Scalar(p1,p2,p3));

But when I do debug in Qt, I see in the local and expression window that the vector v indeed has 1 column and 3 rows but has also 2 dim. I was wondering if this is due to the Mat type in the declaration. With which type could I replace it to get just a simple vector of 3 values?

Upvotes: 4

Views: 24866

Answers (1)

Miki
Miki

Reputation: 41775

Which type could I use to get just a simple vector of 3 values? I want to do some operation on this vector like use the norm and change it's elements.

You can use cv::Vec type.

Assuming you're working on double values (the same applies for other types) you can:

// Create a vector
Vec3d v;

// Assign values / Change elements
v[0] = 1.1;
v[1] = 2.2;
v[2] = 3.3;

// Or initialize in the constructor directly 
Vec3d u(1.1, 2.2, 3.3);

// Read values
double d0 = v[0];

// Compute the norm, using cv::norm 
double norm_L2 = norm(v, NORM_L2); // or norm(v);
double norm_L1 = norm(v, NORM_L1);

For:

  • double type use Vec3d
  • float type use Vec3f
  • int type use Vec3i
  • short type use Vec3s
  • ushort type use Vec3w
  • uchar type use Vec3b

Upvotes: 7

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