Apparatus and method to reduce an amount of coordinate data representing an object taken by an imaging device in a three dimensional space

A non-transitory, computer-readable recording medium having stored therein a program for causing a computer to execute a process comprising:

• obtaining a second straight line by mapping a first straight line that passes a projection center of a target image taken by a first imaging device in a three dimensional space and a point representing an object in a projection plane of the first imaging device, onto each of a plurality of reference images respectively taken by a plurality of second imaging devices, and generating a reference line-segment representing an existing range of the object on the second straight line for each of the plurality of reference images;
• transforming, for each of the plurality of reference line-segments respectively generated on the plurality of reference images, a coordinate value of a first endpoint of the reference line-segment into a difference between a coordinate value of the first end point and a coordinate value of a second endpoint of the reference line-segment;
• storing the coordinate value of the second endpoint and the difference in a memory;
• restoring the coordinate value of the first endpoint from the coordinate value of the second endpoint and the difference stored in the memory;
• and
• mapping the coordinate value of the second endpoint and the restored coordinate value of the first endpoint, onto a depth-direction line that is perpendicular to the projection plane of the first imaging device, and determining overlap of a plurality of line-segments on the depth-direction line whose endpoints are mapped from each of the plurality of reference line-segments on the plurality of reference images.

A method comprising:

• obtaining a second straight line by mapping a first straight line that passes a projection center of a target image taken by a first imaging device in a three dimensional space and a point representing an object in a projection plane of the first imaging device, onto each of a plurality of reference images respectively taken by a plurality of second imaging devices, and generating a reference line-segment representing an existing range of the object on the second straight line for each of the plurality of reference images;
• transforming, for each of the plurality of reference line-segments respectively generated on the plurality of reference images, a coordinate value of a first endpoint of the reference line-segment into a difference between a coordinate value of the first end point and a coordinate value of a second endpoint of the reference line-segment;
• storing the coordinate value of the second endpoint and the difference in a memory;
• restoring the coordinate value of the first endpoint from the coordinate value of the second endpoint and the difference stored in the memory;
• and
• mapping the coordinate value of the second endpoint and the restored coordinate value of the first endpoint, onto a depth-direction line that is perpendicular to the projection plane of the first imaging device, and determining overlap of a plurality of line-segments on the depth-direction line whose endpoints are mapped from each of the plurality of reference line-segments on the plurality of reference images.