code: public void configure( double descriptorRegionScale , double periodX, double periodY) {
  		this.radius = descriptorRegionScale*scaleToRadius;
  		this.periodX = (int)(periodX+0.5);
  		this.periodY = (int)(periodY+0.5);
  		this.featureWidth = (int)(alg.getCanonicalWidth()*descriptorRegionScale + 0.5);
  
  		descriptions = new FastQueue<Desc>(alg.getDescriptionType(),true) {
  			@Override
  			protected Desc createInstance() {
  				return alg.createDescription();
  			}
  		};
  	}
docs: Configures size of the descriptor and the frequency at which it's computed
  
  @param descriptorRegionScale Relative size of the descriptor region to its canonical size
  @param periodX Period in pixels along x-axis of samples
  @param periodY Period in pixels along y-axis of samples