Positioning apparatus and positioning method regarding a position of mobile object

A positioning method for use in a positioning apparatus mounted in a mobile object, said positioning method comprising:

• imaging a first scenery image at a first spot where said mobile object exists;
• extracting a first image feature from said first scenery image having been imaged;
• acquiring a piece of first position information which is a piece of approximate position information related to said mobile object existing at said first spot;
• storing a piece of second position information corresponding to each of second spots which are spots on a movement route along which said mobile object is predicted to move, as well as a second image feature of a second scenery image having been imaged in advance at each of said second spots, into scenery image feature storage means, such that said piece of second position information and said second image feature are correlated with each other;
• on a basis of distances between a spot indicated by said piece of first position information and spots indicated by said respective pieces of second position information, selecting said plurality pieces of second position information and corresponding said plurality of second image features from inside of said scenery image feature storage means;
• collating said first image feature with each of said selected plurality of second image features, and thereby calculating pieces of relative position information between said first spot and said respective second spots corresponding to said selected plurality of second image features;
• and
• determining consistency among said calculated plurality pieces of relative position information, and outputting a piece of determinate position information related to said mobile object on the basis of a result of said determination.

A non-transitory computer readable medium storing therein a program that causes a computer to execute processing for use in a positioning apparatus mounted in a mobile object, said processing comprising the processes of:

• imaging a first scenery image at a first spot where said mobile object exists;
• extracting a first image feature from said first scenery image having been imaged;
• acquiring a piece of first position information which is a piece of approximate position information related to said mobile object existing at said first spot;
• storing a piece of second position information corresponding to each of second spots which are spots on a movement route along which said mobile object is predicted to move, as well as a second image feature of a second scenery image having been imaged in advance at each of said second spots, into scenery image feature storage, such that said piece of second position information and said second image feature are correlated with each other;
• on a basis of distances between a spot indicated by said piece of first position information and spots indicated by said respective pieces of second position information, selecting said plurality pieces of second position information and corresponding said plurality of second image features from inside of said scenery image feature storage;
• collating said first image feature with each of said selected plurality of second image features, and thereby calculating pieces of relative position information between said first spot and said respective second spots corresponding to said selected plurality of second image features;
• and
• determining consistency among said calculated plurality pieces of relative position information, and outputting a piece of determinate position information related to said mobile object on a basis of a result of said determination, each one of the spots being a particular position.