code: public void setPixelPerUnit(double pixelPerUnit) {
  		if (pixelPerUnit < MINIMUM_PIXEL_PER_UNIT) {
  			pixelPerUnit = MINIMUM_PIXEL_PER_UNIT;
  		}
  		if (pixelPerUnit > MAXIMUM_PIXEL_PER_UNIT) {
  			pixelPerUnit = MAXIMUM_PIXEL_PER_UNIT;
  		}
  		this.pixelPerUnit = pixelPerUnit;
  		setPixelPerUnitBased(true);
  		postConstruct();
  	}
docs: Sets the scale value in pixel per map unit.
  
  @param pixelPerUnit
  the scale value (pix/map unit)