To save vector "KeyPoint" to file using builtin write function

ipunished
116 ●1 ●1 ●6

Hi,

I want to write a vector of detected Keypoints to file and while I was told it can be done through operator overloading, I found out a function in the keypoint class documentation.

The documentation here shows a function called write..

// reading/writing a vector of keypoints to a file storage
void write(FileStorage& fs, const string& name, const vector<KeyPoint>& keypoints);
void read(const FileNode& node, vector<KeyPoint>& keypoints);

So basically there is a function to write the vector to file.. can some one please explain this and also, an example on how to use this would be great.

Thank you

answered Nov 11 '12

Simone
372 ●2 ●3 ●12

updated Nov 11 '12

Hi,

it's actually simple. In order to save your keypoints

 vector<Keypoint> mykpts;
 FileStorage fs("keypoints.yml", FileStorage::WRITE);
 write( fs , "aNameYouLike", mykpts );
 fs.release();

This will store your keypoints in a file named keypoints.yml and the node containing the data is named "aNameYouLike". This will be used to read back the keypoints from the file:

  vector<Keypoint> mykpts2;
  FileStorage fs2("keypoints.yml", FileStorage::READ);
  FileNode kptFileNode = fs2["aNameYouLike"];
  read( kptFileNode, mykpts2 );
  fs2.release();

You may want to check the XML/YAML file storage documentation for more information.

Hope it helps

Comments

Thank you. That was very helpful. I wish I could upvote this more than once.

ipunished (Nov 11 '12)edit

thank you very much too! the information was very useful

Olbitla (Dec 5 '12)edit

i am using XML storage way.It can save keypoint perfectly of first image. now i want that i used for loop and it save my image keypoint one by one.so how can i do it.

salman (Oct 13 '17)edit

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