code: public static CalibrationDetectorSquareGrid squareGrid(@Nullable ConfigSquareGrid config, ConfigGridDimen configDimen) {
  		if( config == null )
  			config = new ConfigSquareGrid();
  		config.checkValidity();
  
  		return new CalibrationDetectorSquareGrid(config,configDimen);
  	}
docs: Detector for a grid of square targets.   All squares must be entirely visible inside the image.
  
  @see boofcv.alg.fiducial.calib.grid.DetectSquareGridFiducial
  
  @param config Configuration for chessboard detector
  @return Square grid target detector.