Device, method, and computer readable medium for area identification using motion from a projected pattern
An area identifying device includes a projecting unit, an image capturing unit, a calculating unit, and an identifying unit. The projecting unit is configured to project a pattern so that the pattern performs a predetermined movement. The image capturing unit is configured to capture, in sequential order, multiple images of a projection area on which the pattern is projected, each image including a plurality of image areas. The calculating unit is configured to calculate an amount of change of pattern appearances for each image area in the multiple images. The identifying unit is configured to identify, as a reflective area, at least one image area having a different amount of change of the pattern appearances from a reference amount of change of the pattern appearances based on the predetermined movement, among the calculated amounts of change of the pattern appearances.
1. An area identifying device comprising:
a projecting unit configured to project a pattern so that the pattern performs a predetermined movement;
an image capturing unit configured to capture, in time-sequential order, images of projection areas on which the pattern is projected; and
a processor configured to execute a program to implement a calculating unit and an identifying unit,
the calculating unit being configured to calculate, based on pixel values of the images, an amount of change of pattern appearances for each of multiple image areas in the images, and
the identifying unit being configured to identify, as a spatial location of a reflective area of a physical item that has a constant reflectance ratio, at least one image area having a different amount of change of the pattern appearances from a reference amount of change of the pattern appearances based on the predetermined movement, among the calculated amounts of change of the pattern appearances.
2. The device according to claim 1 , wherein the identifying unit calculates differences between the reference amount of change of the pattern appearances and the respective calculated amounts of change of the pattern appearances, and identifies, as the spatial location of the reflective area, an image area having an amount of change of the pattern appearances for which the calculated difference is equal to or greater than a threshold value.
3. The device according to claim 1 , wherein the projecting unit projects the pattern while shifting the pattern in an oblique direction with respect to a coordinate system of the projecting unit.
4. The device according to claim 1 , wherein
the pattern is a gradation pattern, and
the amount of change of the pattern appearances is a brightness value difference.
5. The device according to claim 1 , wherein
the pattern is a sinusoidal pattern, and
the amount of change of the pattern appearances is a phase.
6. The device according to claim 1 , wherein the identifying unit sets, as an unidentifiable area, an image area having the calculated amount of change of the pattern appearances that is equal to or smaller than a threshold value.
7. An area identifying device, comprising:
a projecting unit configured to project a pattern so that the pattern performs a predetermined movement;
an image capturing unit configured to capture, in time-sequential order, images of projection areas on which the pattern is projected; and
a processor configured to execute a program to implement a calculating unit and an identifying unit,
the calculating unit being configured to calculate, based on pixel values of the images, an amount of change of pattern appearances for each of multiple image areas in the images, and
the identifying unit being configured to identify, as a spatial location of a reflective area of a physical item that has a constant reflectance ratio, at least one image area having a different amount of change of the pattern appearances from a reference amount of change of the pattern appearances based on the predetermined movement, among the calculated amounts of change of the pattern appearances, wherein
the pattern is a geometrical pattern, and
the amount of change of the pattern appearances is a motion vector.
8. The device according to claim 7 , wherein the geometrical pattern comprises a lattice in which a plurality of transverse lines having random thicknesses are crossed at random positions.
9. An area identifying method comprising:
projecting a pattern so that the pattern performs a predetermined movement;
capturing, in time-sequential order, images of projection areas on which the pattern is projected;
calculating, based on pixel values of the images, an amount of change of pattern appearances for each of multiple image areas in the images; and
identifying, as a spatial location of a reflective area of a physical item that has a constant reflectance ratio, at least one image area having a different amount of change of the pattern appearances from a reference amount of change of the pattern appearances based on the predetermined movement, among the calculated amounts of change of the pattern appearances.
10. A computer program product comprising a non-transitory computer-readable medium containing a program which, when executed by a computer, causes the computer to execute at least:
projecting a pattern so that the pattern performs a predetermined movement;
capturing, in time-sequential order, images of projection areas on which the pattern is projected;
calculating, based on pixel values of the images, an amount of change of pattern appearances for each of multiple image areas in the images; and
identifying, as a spatial location of a reflective area of a physical item that has a constant reflectance ratio, at least one image area having a different amount of change of the pattern appearances from a reference amount of change of the pattern appearances based on the predetermined movement, among the calculated amounts of change of the pattern appearances.