docs: private void addDescriptor(boolean positive, NccFeature f) {
  		// avoid adding the same descriptor twice or adding contradicting results
  		if( positive)
  			if( distance(f,templatePositive) < 0.05 ) {
  				return;
  			}
  		if( !positive) {
  			if( distance(f,templateNegative) < 0.05 ) {
  				return;
  			}
  			// a positive positive can have very bad affects on tracking, try to avoid learning a positive
  			// example as a negative one
  			if( distance(f,templatePositive) < 0.05 ) {
  				return;
  			}
  		}
  
  		if( positive )
  			templatePositive.add(f);
  		else
  			templateNegative.add(f);
  	}