Travel road shape recognition apparatus and travel road shape recognition method

A travel road shape recognition method comprising:

• an image acquiring step of acquiring a captured image of an area ahead of an own vehicle in an advancing direction of the own vehicle, from an imaging means;
• a first shape calculating step of calculating a first travel road shape approximating a shape of a travel road boundary of a travel road on which the own vehicle is traveling based on a plurality of feature points indicating the travel road boundary in the captured image;
• a position detecting step of detecting a worsening position over an area from near to far from the own vehicle in the captured image, the worsening position being a position on the first travel road shape at which a degree of coincidence with the feature points worsens;
• a second shape calculating step of calculating a second travel road shape approximating the shape of the travel road boundary in an area farther from the own vehicle, beyond the worsening position, in the captured image, when the worsening position is detected;
• and
• a recognizing step of recognizing the travel road boundary in the area nearer to the own vehicle, up to the worsening position, from the first travel road shape, and the travel road boundary in the area farther from the own vehicle, beyond the worsening position, from the second travel road shape.