Three-dimensional printing system and method of printing a three-dimensional object

A three-dimensional printing system, comprising:

• a three-dimensional printing device that prints a three-dimensional printing object;
• a region determination device for a slice model, the region determination device dividing a region of the slice model into a printing region to be printed and a non-printing region not to be printed, the slice model being obtained as a result of slicing a three-dimensional model of a three-dimensional printing object at a predetermined interval and being defined by contours representing profiles of the three-dimensional printing object, wherein the contours include an island contour representing a shape of an outer profile of the printing region of the three-dimensional printing object and a hole contour representing a shape of a hole in the three-dimensional printing object, the region determination device comprising:
• a storage processor that stores the slice model and an internal level variable and a temporary retain variable;
• an advancing direction setting processor that sets an advancing direction for the island contour of the slice model stored by the storage processor and a different advancing direction for the hole contour of the slice model;
• a scanning line setting processor that sets, for the slice model stored by the storage processor, a scanning line directed in a predetermined direction so as to cross the contours;
• an intersection specifying processor that specifies intersections at which the contours and the scanning line cross each other;
• a contour determination processor that determines whether each of the contours crossing the scanning line at the intersections specified by the intersection specifying processor is the island contour or the hole contour;
• a first internal level setting processor that, in a case in which the contour crossing the scanning line is determined to be the island contour by the contour determination processor, when the island contour crosses the scanning line in a first direction, increases a value of the internal level variable by a predetermined value, and when the island contour crosses the scanning line in a second direction opposite to the first direction, decreases the value of the internal level variable by the predetermined value;
• a second internal level setting processor that, in a case in which the contour crossing the scanning line is determined to be the hole contour by the contour determination processor, when the hole contour crosses the scanning line in the second direction, assigns the value of the internal level variable to the temporary retain variable and then substitutes “0” for the internal level variable, and when the hole contour crosses the scanning line in the first direction, assigns a value of the temporary retain variable back to the internal level variable;
• a region determination processor that determines a region, corresponding to a value of the internal level variable that is not 0, to be the printing region and determines a region, corresponding to the value of the internal level variable that is 0, to be the non-printing region, the internal level variable being set by the first internal level setting processor and the second internal level setting processor, wherein
• the three-dimensional printing device prints the three-dimensional printing object according to the printing region and the non-printing region determined by the region determination processor.