Memory leak problem using CvExtractSURF

advanced
#1

Hello,

I want to extract SURF points and create an XML with the information from a series of keyframes of a video.

This is the function that does the work:

  
  
void xVideo::extractSURFDescriptor(int f1){  
	ofxXmlSettings *surfXML = new ofxXmlSettings();  
	imageKeypoints = 0;  
	imageDescriptors = 0;  
	surfXML->addTag( "SURF" );  
	surfXML->pushTag( "SURF" , 0 );  
	ofxCvColorImage *image = new ofxCvColorImage();  
	image->allocate( getWidth(), getHeight() );  
	image->setFromPixels( getPixels(), getWidth(), getHeight() );  
		  
	ofxCvGrayscaleImage *imageGray = new ofxCvGrayscaleImage();  
	imageGray->allocate( image->getWidth(), image->getHeight() );  
	imageGray->setFromColorImage( *image );  
	  
	cvExtractSURF( imageGray->getCvImage(), 0, &imageKeypoints, &imageDescriptors, storage, params );	  
	  
	CvSeqReader reader, kreader;  
	cvStartReadSeq( imageKeypoints, &kreader );  
	cvStartReadSeq( imageDescriptors, &reader );  
	int len = (int) ( imageDescriptors->elem_size/sizeof(float) );  
	for( int i = 0; i < imageDescriptors->total ; i++ ){  
		const CvSURFPoint* kp = (const CvSURFPoint*)kreader.ptr;  
		surfXML->addTag( "INFO" );  
		surfXML->pushTag( "INFO" , i );  
		surfXML->addValue( "X", kp->pt.x );  
		surfXML->addValue( "Y", kp->pt.y );  
		surfXML->addValue( "LAPLACIAN" , kp->laplacian );  
		const float* descriptor = (const float*)reader.ptr;  
		for (int d = 0 ; d < len ; d++) {  
			surfXML->addValue( "V", descriptor[d] );  
		}  
		surfXML->popTag();  
		CV_NEXT_SEQ_ELEM( kreader.seq->elem_size, kreader );  
		CV_NEXT_SEQ_ELEM( reader.seq->elem_size, reader );  
	}  
	surfXML->saveFile( title + "/xml/surf/s" + ofToString( f1 ) + ".xml" );  
	  
	image->clear();  
	imageGray->clear();  
	cvClearMemStorage( storage );  
	surfXML->clear();  
}

I have storage and params initialize on the class constructor

  
  
xVideo::xVideo(){  
        //...  
	storage = cvCreateMemStorage( 0 );	  
	params = cvSURFParams( 500, 1 );  
}

and on the .h of the class

  
  
        CvMemStorage* storage;  
	CvSURFParams params;   
	CvSeq *imageKeypoints, *imageDescriptors;

When the program enters this function he isn’t cleaning memory, I call the clear for image, imageGray and surfXML and do the cvClearMemStorage for the storage.

Can anyone help me?

thank you
João

#2

cvclearmemstorage doesn’t release any memory it just deletes the contents of the mem storage, from opencv docs:

The function resets the top (free space boundary) of the storage to the very beginning. This function does not deallocate any memory. If the storage has a parent, the function returns all blocks to the parent.

what you want is cvReleaseMemStorage

#3

The problem continues, i substitute

  
  
cvClearMemStorage( storage );

for

  
  
cvReleaseMemStorage( &storage );

and added

  
storage = cvCreateMemStorage( 0 );

to the beginning to the function and memory keeps increasing.

#4

oh yes, the clear can be ok if you’re allocating in the constructor and using that memory after that.

this:

  
  
imageGray = new ofxCvGrayscaleImage()

and

  
ofxXmlSettings *surfXML = new ofxXmlSettings();

though, is done every time so you need to delete it at the end:

  
delete imageGray;  
delete surfXML

or even better, if you know the size of the image size at the beginning, you can just declare imageGray as a variable in the .h and allocate it at the beginning. the same goes for surfXML. it will be even faster since you don’t need to initialize the instances every time.

#5

i thought the

  
  
imageGray->clear();

would do release. I have put the delete on both images and the xml file and memory still grows :slight_smile:

#6

hi~ glad to see discussion about surf here. i also find the memory leak problem with this method. i doubt it’s because imageKeypoints and imageDescriptors? because each cycle there are:
imageKeypoints = 0
imageDescriptors = 0
so maybe these memories are not released

#7

it’s not enough to call clear() on the images. for every call to new, you need a matching delete:

ofImage* imageGrey = new ofImage();

…

delete imageGrey;

#8

Hi UnZynpernet,

Finally you could fix the problem with memory. I am in the same case and not know where to shoot.

thanks!!

#9

Fix:

// create memory
imaStorage = cvCreateMemStorage(0);

//exec SURF
cvExtractSURF( oCVgrayImg.getCvImage(), 0, &imageKeypoints, &imageDescriptors, imaStorage, params);

//find homograpy
imaEncontrados = locatePlanarObject( objectKeypoints, objectDescriptors, imageKeypoints, imageDescriptors, src_corners, dst_corners );

//delete an reset memory
cvReleaseMemStorage(&imaStorage);

And the memory dont grow… :slight_smile: