Calibration method, non-transitory recording medium, and calibration device

A non-transitory recording medium recording a calibration program of an imaging device including a wide angle lens, the program causing a computer to execute processing including:

• acquiring a first image captured by the imaging device, at least a portion of a pattern surface being projected to the first image, at least a portion of a first mirror surface provided on a first surface being projected to the first image, at least a portion of a second mirror surface provided on a second surface being projected to the first image, a calibration pattern being provided in the pattern surface, the first surface intersecting the pattern surface, the second surface intersecting the pattern surface and being parallel to the first surface, the second mirror surface opposing the first mirror surface;
• extracting a part of the first image where the pattern surface is projected as a first pattern region, a first mirror image of the pattern surface formed on the first mirror surface appearing in the first pattern region, a second mirror image of the pattern surface formed on the second mirror surface appearing in the first pattern region;
• and
• calibrating a parameter of the imaging device based on the first pattern region, the parameter including a focal length of the wide angle lens.

A calibration device, comprising:

• a pattern surface, a calibration pattern being provided in the pattern surface;
• a first mirror surface provided on a first surface intersecting the pattern surface;
• and
• a second mirror surface provided on a second surface to oppose the first mirror surface, the second surface intersecting the pattern surface and being parallel to the first surface,
• the device being capable of placing a wide angle lens of an imaging device at a position between the first mirror surface and the second mirror surface, the position being separated from the pattern surface,
• the device being used to calibrate a parameter of the imaging device based on a first image captured by the imaging device.