Apparatus and method for estimating orientation of camera

An orientation estimation method, comprising:

• detecting a marker from an image acquired from an image capturing unit that creates the image of a photographed range at a predetermined photographing cycle;
• estimating, based on a position of the marker on the image and a position of the marker in a real space, a position and an orientation of the image capturing unit;
• detecting, when the marker is not detected from the image, a plurality of feature points from the image and a subsequent image to be acquired after the image;
• estimating the position and the orientation of the image capturing unit based on positions of the plurality of feature points on the image, positions of the plurality of feature points in the real space, and initial values of the position and the orientation of the image capturing unit;
• calculating, from a first image acquired while the position and the orientation of the image capturing unit are estimated based on the position of the marker on the image and the position of the marker in the real space, at least one failure index indicating a possibility that the detection of the marker is failed, and determining whether or not the at least one failure index satisfies a shift preparation start reference;
• and
• setting, when the at least one failure index satisfies the shift preparation start reference, the initial values of the position and the orientation of the image capturing unit from the position and the orientation of the image capturing unit estimated based on the position of the marker on the image having been acquired in a predetermined period before the first image,
• wherein the marker is determined to not be detected from the image based on the calculated at least one failure index.

A non-transitory computer-readable recording medium storing an orientation estimation computer program for causing a computer to execute a process, the process comprising:

• detecting a marker from an image acquired from an image capturing unit that creates the image of a photographed range at a predetermined photographing cycle;
• estimating, based on a position of the marker on the image and a position of the marker in a real space, a position and an orientation of the image capturing unit;
• detecting, when the marker is not detected from the image, a plurality of feature points from the image and a subsequent image to be acquired after the image;
• estimating the position and the orientation of the image capturing unit based on positions of the plurality of feature points on the image, positions of the plurality of feature points in the real space, and initial values of the position and the orientation of the image capturing unit;
• calculating, from a first image acquired while the position and the orientation of the image capturing unit are estimated based on the position of the marker on the image and the position of the marker in the real space, at least one failure index indicating a possibility that the detection of the marker is failed, and determine whether or not the at least one failure index satisfies a shift preparation start reference;
• and
• setting, when the at least one failure index satisfies the shift preparation start reference, the initial values of the position and the orientation of the image capturing unit from the position and the orientation of the image capturing unit estimated based on the position of the marker on the image having been acquired in a predetermined period before the first image,
• wherein the marker is determined to not be detected from the image based on the calculated at least one failure index.