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Home » Community » Newbie corner » stl question
stl question [message #32796] Fri, 10 June 2011 05:37 Go to next message
GaroRobe is currently offline  GaroRobe
Messages: 30
Registered: May 2011
Location: Khabarovsk, Russia
Member

So.

I've got a method in OpenCV I need to use. It has parameters with type vector<vector<Point3d>>. It is a data about primitive regular mesh (in model coords) for each frame. Filling it manually feels wrong, so I do it like:
vector<Point2f> checkboardMesh;

for ( int i = 0; i < board_h; i++ )
		for ( int j = 0; j < board_w;i++ )
			checkboardMesh.push_back ( * new Point2f ( j, i ) );

And here I get stuck: will I not get memory leak here? AFAIK std::vector copies element on insert. Should I do it like
for ( int i = 0; i < board_h; i++ )
for ( int j = 0; j < board_w; j++ )
{
	tmpP = new Point2f ( j, i );
	checkboardMesh.push_back ( *tmpP );
	delete tmpP;
}

maybe? If I do, then I'd rather look for a better idea.

Or maybe there is some way of using Upp containers here?

P.S.: The method I mentioned is cv::calibrateCamera btw:
double cv::calibrateCamera( const vector<vector<Point3f> >& objectPoints,
                          const vector<vector<Point2f> >& imagePoints,
                          Size imageSize, Mat& cameraMatrix, Mat& distCoeffs,
                          vector<Mat>& rvecs, vector<Mat>& tvecs, int flags )
Re: stl question [message #32797 is a reply to message #32796] Fri, 10 June 2011 07:55 Go to previous messageGo to next message
dolik.rce is currently offline  dolik.rce
Messages: 1789
Registered: August 2008
Location: Czech Republic
Ultimate Contributor

Hi GaroRobe,

You don't have to use new at all Wink Just creating a temporary object is fine, since std::vector will make a copy:
vector<Point2f> checkboardMesh;

for ( int i = 0; i < board_h; i++ )
		for ( int j = 0; j < board_w; j++ )
			checkboardMesh.push_back ( Point2f ( j, i ) );


Using U++ containers should be possible, but it would be an ugly hack Smile Something allong the lines of:
	using std::vector;
	using cv::Point2f;

	Vector<Point2f> v; //this requires to do NAMESPACE_UPP; NTL_MOVEABLE(cv::Point2f); END_UPP_NAMESPACE; in global scope

	vector<Point2f> checkboardMesh;

	for ( int i = 0; i < board_h; i++ )
		for ( int j = 0; j < board_w; j++ )
			v.Add( Point2f ( j, i ) );
	
	checkboardMesh.resize(v.GetCount());
	memmove(&checkboardMesh[0],v.Begin(),v.GetCount()*sizeof(Point2f));
In other words: not elegant and definitelly not recomended. Please never do something like that Wink

Honza
Re: stl question [message #32799 is a reply to message #32797] Fri, 10 June 2011 08:21 Go to previous message
GaroRobe is currently offline  GaroRobe
Messages: 30
Registered: May 2011
Location: Khabarovsk, Russia
Member

Wouldn't have guessed. Thanks a lot Smile
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