code: public void process( double c_x , double c_y , double sigma , double orientation , TupleDesc_F64 descriptor )
  	{
  		descriptor.fill(0);
  
  		computeRawDescriptor(c_x, c_y, sigma, orientation, descriptor);
  
  		normalizeDescriptor(descriptor,maxDescriptorElementValue);
  	}
docs: Computes the SIFT descriptor for the specified key point
  
  @param c_x center of key point.  x-axis
  @param c_y center of key point.  y-axis
  @param sigma Computed sigma in scale-space for this point
  @param orientation Orientation of keypoint in radians
  @param descriptor (output) Storage for computed descriptor.  Make sure it's the appropriate length first