State determination apparatus, state determination method, and computer-readable recording medium

1 . A state determination apparatus comprising:

at least one memory storing instructions; and

at least one processor configured to execute the instructions to:

acquire, as a fixed image, each of time-series images obtained by continuously shooting a rotating object with an image capturing apparatus via a first optical device that rotates and emits incident light;

calculate a displacement amount of a plurality of specific points on the object, using each of the acquired fixed images, and, with one of the plurality of specific points as a reference specific point, calculate a difference between the displacement amount of the reference specific point and the displacement amount of each specific point other than the reference specific point;

calculate, as an out-of-plane displacement, a displacement of a surface of the object on an image plane of the image capturing apparatus following movement of the object in a normal direction of the image plane, using the difference;

calculate, as an in-plane displacement, a displacement of the surface of the object on the image plane following movement of the surface of the object in a direction along the surface, using the difference and the out-of-plane displacement; and

specify an abnormality of the object, based on a distribution of the in-plane displacement or a temporal change of the out-of-plane displacement.

2 . The state determination apparatus according to claim 1 ,

further at least one processor configured to execute the instructions to:

acquire the fixed images, by detecting a rotation direction and rotation speed of the object, and controlling a rotation direction and rotation speed of the incident light in the first optical device, based on the detected rotation direction and rotation speed.

3 . The state determination apparatus according to claim 2 ,

further at least one processor configured to execute the instructions to:

wherein the first optical device has two or more prism elements, is configured such that the two or more prism elements rotate independently to each other about an optical axis of the incident light, and is installed such that the optical axis of the incident light coincides with a normal on the image plane of the image capturing apparatus, and

further at least one processor configured to execute the instructions to:

rotate the two or more prism elements in opposite directions to each other, and control a rotation direction and rotation speed of the two or more prism elements, such that an image captured by the image capturing apparatus through the two or more prism elements rotates at the same rotation speed as the rotation speed of the object in an opposite direction to the rotation direction of the object.

4 . The state determination apparatus according to claim 1 ,

wherein a second optical device is disposed between the object and the first optical device, and is configured to track translational movement of the object, take an image of the object and cause the taken image to be incident on the first optical device, and

further at least one processor configured to execute the instructions to:

detect a direction of the translational movement of the object and a movement amount at a time of the translational movement, and control the second optical device, based on the detected translational direction and translational movement amount.

5 . The state determination apparatus according to claim 1 ,

further at least one processor configured to execute the instructions to:

derive a depth movement amount of the surface of the object that has moved in the normal direction using the difference, and calculate the out-of-plane displacement using the depth movement amount.

6 . A state determination method comprising:

acquiring, as a fixed image, each of time-series images obtained by continuously shooting a rotating object with an image capturing apparatus via a first optical device that rotates and emits incident light;

calculating a displacement amount of a plurality of specific points on the object, using each of the acquired fixed images, and, with one of the plurality of specific points as a reference specific point, calculating a difference between the displacement amount of the reference specific point and the displacement amount of each specific point other than the reference specific point;

calculating, as an out-of-plane displacement, a displacement of a surface of the object on an image plane of the image capturing apparatus following movement of the object in a normal direction of the image plane, using the difference;

calculating, as an in-plane displacement, a displacement of the surface of the object on the image plane following movement of the surface of the object in a direction along the surface, using the difference and the out-of-plane displacement; and

specifying an abnormality of the object, based on a distribution of the in-plane displacement or a temporal change of the out-of-plane displacement.

7 . The state determination method according to claim 6 ,

wherein, in the acquiring the fixed image, acquiring the fixed images, by detecting a rotation direction and rotation speed of the object, and controlling a rotation direction and rotation speed of the incident light in the first optical device, based on the detected rotation direction and rotation speed.

8 . The state determination method according to claim 7 ,

wherein the first optical device has two or more prism elements, is configured such that the two or more prism elements rotate independently to each other about an optical axis of the incident light, and is installed such that the optical axis of the incident light coincides with a normal on the image plane of the image capturing apparatus, and

in the acquiring the fixed image, rotating the two or more prism elements in opposite directions to each other, and controlling a rotation direction and rotation speed of the two or more prism elements, such that an image captured by the image capturing apparatus through the two or more prism elements rotates at the same rotation speed as the rotation speed of the object in an opposite direction to the rotation direction of the object.

9 . The state determination method according to claim 6 ,

wherein a second optical device is disposed between the object and the first optical device, and is configured to track translational movement of the object, take an image of the object and cause the taken image to be incident on the first optical device, and

in the acquiring the fixed image, detecting a direction of the translational movement of the object and a movement amount at a time of the translational movement, and controlling the second optical device, based on the detected translational direction and translational movement amount.

10 . The state determination method according to claim 6 ,

wherein, in the calculating the out-of-plane displacement, deriving a depth movement amount of the surface of the object that has moved in the normal direction using the difference, and calculating the out-of-plane displacement using the depth movement amount.

11 . A non-transitory computer-readable recording medium including a program recorded thereon, the program including instructions that cause a computer to carry out:

acquiring, as a fixed image, each of time-series images obtained by continuously shooting a rotating object with an image capturing apparatus via a first optical device that rotates and emits incident light;

calculating a displacement amount of a plurality of specific points on the object, using each of the acquired fixed images, and, with one of the plurality of specific points as a reference specific point, calculating a difference between the displacement amount of the reference specific point and the displacement amount of each specific point other than the reference specific point;

calculating, as an out-of-plane displacement, a displacement of a surface of the object on an image plane of the image capturing apparatus following movement of the object in a normal direction of the image plane, using the difference;

calculating, as an in-plane displacement, a displacement of the surface of the object on the image plane following movement of the surface of the object in a direction along the surface, using the difference and the out-of-plane displacement; and

specifying an abnormality of the object, based on a distribution of the in-plane displacement or a temporal change of the out-of-plane displacement.

12 . The non-transitory computer-readable recording medium according to claim 11 ,

wherein, in the acquiring the fixed image, acquiring the fixed images, by detecting a rotation direction and rotation speed of the object, and controlling a rotation direction and rotation speed of the incident light in the first optical device, based on the detected rotation direction and rotation speed.

13 . The non-transitory computer-readable recording medium according to claim 12 ,

wherein the first optical device has two or more prism elements, is configured such that the two or more prism elements rotate independently to each other about an optical axis of the incident light, and is installed such that the optical axis of the incident light coincides with a normal on the image plane of the image capturing apparatus, and

in the acquiring the fixed image, rotating the two or more prism elements in opposite directions to each other, and controlling a rotation direction and rotation speed of the two or more prism elements, such that an image captured by the image capturing apparatus through the two or more prism elements rotates at the same rotation speed as the rotation speed of the object in an opposite direction to the rotation direction of the object.

14 . The non-transitory computer-readable recording medium according to claim 11 ,

wherein a second optical device is disposed between the object and the first optical device, and is configured to track translational movement of the object, take an image of the object and cause the taken image to be incident on the first optical device, and

in the acquiring the fixed image, detecting a direction of the translational movement of the object and a movement amount at a time of the translational movement, and controlling the second optical device, based on the detected translational direction and translational movement amount.

15 . The non-transitory computer-readable recording medium according to claim 11 ,

wherein, in the calculating the out-of-plane displacement, deriving a depth movement amount of the surface of the object that has moved in the normal direction using the difference, and calculating the out-of-plane displacement using the depth movement amount.