THREE-DIMENSIONAL-SHAPE MEASUREMENT APPARATUS, THREE-DIMENSIONAL-SHAPE MEASUREMENT METHOD, AND NON-TRANSITORY COMPUTER-READABLE STORAGE MEDIUM

• US 20150204662A1
• Filed: 01/09/2015
• Published: 07/23/2015
• Est. Priority Date: 01/17/2014
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kobayashi, Toshihiro, Higo, Tomoaki, Yamasaki, Masayoshi
• Granted Patent: US 9,557,167 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01B 11/25 by projecting a pattern, e.g. one or more lines, moiré fringes on the object G01B11/255 takes precedence ; image analysis for depth or shape recovery G06T7/50
• CPC Class Codes: G01B 11/2513 with several lines being projected in more than one direction, e.g. grids, patterns

Abstract

A first image of a space onto which a first light pattern formed from bright and dark portions and a coordinate-detection pattern projected onto each region of the space divided by the first pattern have been projected is acquired. A second image is acquired of the space onto which a second light pattern having a boundary position between bright and dark portions that is different from that of the first pattern, and a coordinate-detection pattern projected onto each region of the space divided by the second pattern have been projected. One of the first image and the second image is selected to perform three-dimensional shape measurement of an object included in the space based on the selection image.

Claims

1. A three-dimensional-shape measurement apparatus comprising:

a first acquisition unit configured to acquire a first captured image of a space onto which a first light pattern formed from a bright portion and a dark portion has been projected;

a second acquisition unit configured to acquire a second captured image of the space onto which has been projected a second light pattern formed from a bright portion and a dark portion and having a boundary position between the bright portion and the dark portion that is different from that of the first pattern;

a selection unit configured to select, for each of at least one predetermined region of the first captured image or the second captured image, based on a luminance value in the first captured image and a luminance value in the second captured image, one of the first captured image and the second captured image containing the at least one predetermined region as a selection image to be used for three-dimensional-shape measurement; and

a measurement unit configured to perform three-dimensional-shape measurement of an object included in the space based on the selection image selected by said selection unit.

2. The apparatus according to claim 1, wherein said measurement unit is operable to perform three-dimensional-shape measurement of the object using a pixel value located in the predetermined region in the selection image.

3. The apparatus according to claim 1, wherein each of the first captured image and the second captured image is formed from a non-inverted image as a captured image of the space onto which a pattern formed from a bright portion and a dark portion has been projected, and an inverted image as a captured image of the space onto which a pattern obtained by inverting the bright portion and the dark portion of the pattern has been projected, and

for each predetermined region, said selection unit is operable to acquire, as a first difference, a difference between a luminance value in the predetermined region within the non-inverted image as the first captured image and a luminance value in the predetermined region within the inverted image as the first captured image, and to acquire, as a second difference, a difference between a luminance value in the predetermined region within the non-inverted image as the second captured image and a luminance value in the predetermined region within the inverted image as the second captured image, and

selects one of the first captured image and the second captured image as a selection image based on the first difference and the second difference.

4. The apparatus according to claim 3, wherein said selection unit is operable to select the first captured image as the selection image for the predetermined region where the first difference is larger than the second difference, and to select the second captured image as the selection image for the predetermined region where the first difference is smaller than the second difference.

5. The apparatus according to claim 1, wherein the first captured image includes an image of the space where a coordinate-detection pattern is projected onto each region of the space divided by projecting the first pattern, and

the second captured image includes an image of the space where a coordinate-detection pattern is projected onto each region of the space divided by projecting the second pattern.

6. The apparatus according to claim 5, wherein said measurement unit is operable to specify, among the respective regions of the space divided by projecting the pattern in the selection image, a region onto which the coordinate-detection pattern in the selection image has been projected, and to perform the three-dimensional-shape measurement using a correspondence between the coordinate-detection pattern in the selection image and the coordinate-detection pattern projected onto the specified region among coordinate-detection patterns projected for the selection image.

7. The apparatus according to claim 5, wherein the coordinate-detection patterns are broken-line patterns in which luminance values are discontinuous.

8. The apparatus according to claim 5, wherein the coordinate-detection patterns are a plurality of patterns generated by sequentially shifting broken lines in a longitudinal direction with respect to the broken lines.

9. The apparatus according to claim 1, wherein the first pattern and the second pattern are patterns in which a boundary portion between a bright portion and a dark portion is masked.

10. The apparatus according to claim 1, further comprising:

a unit configured to generate a captured image of a reflected light component obtained by removing the influence of subsurface scattering occurring in the object from the selection image,

wherein said measurement unit is operable to perform the three-dimensional-shape measurement using the captured image of the reflected light component as the selection image.

11. The apparatus according to claim 1, wherein the first pattern and the second pattern are patterns based on Gray codes.

12. The apparatus according to claim 1, wherein:

the first pattern includes a plurality of patterns each formed from a bright portion and a dark portion, a width of at least one of the bright portion and the dark portion being different between the different patterns,

the first captured image indicates a group of captured images obtained by capturing the plurality of patterns,

the second pattern includes a plurality of patterns each formed from a bright portion and a dark portion, a width of at least one of the bright portion and the dark portion being different between the patterns, and

the second captured image indicates a group of captured images obtained by capturing the plurality of patterns.

13. The apparatus according to claim 1, wherein the object is a translucent object.

14. The apparatus according to claim 1, further comprising:

a projection unit configured to project each of the first pattern and the second pattern; and

an image capturing unit configured to capture the first captured image of the space onto which the first pattern has been projected, and the second captured image of the space onto which the second pattern has been projected.

15. A three-dimensional-shape measurement method comprising:

a first acquisition step of acquiring a first captured image of a space onto which a first light pattern formed from a bright portion and a dark portion has been projected;

a second acquisition step of acquiring a second captured image of the space onto which a second light pattern has been projected formed from a bright portion and a dark portion and having a boundary position between the bright portion and the dark portion that is different from that of the first pattern;

a selection step of selecting, for each predetermined region of the first captured image or the second captured image, based on a luminance value in the first captured image and a luminance value in the second captured image, one of the first captured image and the second captured image as a selection image to be used for three-dimensional shape measurement; and

a measurement step of performing three-dimensional shape measurement of an object included in the space based on the selection image selected in the selection unit.

16. A non-transitory computer-readable storage medium storing a computer program for causing a computer to function as

a first acquisition unit configured to acquire a first captured image of a space onto which a first light pattern formed from a bright portion and a dark portion has been projected;

a second acquisition unit configured to acquire a second captured image of the space onto which has been projected a second light pattern formed from a bright portion and a dark portion and having a boundary position between the bright portion and the dark portion, that is different from that of the first pattern;

a selection unit configured to select, for each predetermined region of the first captured image or the second captured image, based on a luminance value in the first captured image and a luminance value in the second captured image, one of the first captured image and the second captured image as a selection image to be used for three-dimensional shape measurement; and

a measurement unit configured to perform three-dimensional shape measurement of an object included in the space based on the selection image selected by said selection step.