MEASUREMENT APPARATUS AND CONTROL METHOD

• US 20080267454A1
• Filed: 04/23/2008
• Published: 10/30/2008
• Est. Priority Date: 04/26/2007
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kobayashi, Kazuhiko, Uchiyama, Shinji
• Granted Patent: US 8,326,021 B2
• Time in Patent Office: Days
• US Class Current: 382/106
• CPC Class Codes: G01B 11/14 for measuring distance or clearance between spaced objects or spaced apertures G01B11/26 takes precedence; rangefinders G01C3/00
• CPC Class Codes: G06T 2207/30244 Camera pose
• CPC Class Codes: G06T 7/33 using feature-based methods
• CPC Class Codes: G06T 7/73 using feature-based methods
• CPC Class Codes: G06V 20/64 Three-dimensional objects

Abstract

A measurement apparatus (100), which measures the relative position and orientation of an image-capturing apparatus (50) capturing images of one or more measurement objects (10) with respect to the measurement object, acquires a captured image using the image-capturing apparatus (50). Moreover, the respective geometric features present in a 3D model of the measurement object (10) are projected onto the captured image based on the position and orientation of the image-capturing apparatus (50), thereby obtaining projection geometric features. Projection geometric features to be used in calculation of the position and orientation are then selected from the resultant projection geometric features based on distances between the projection geometric features in the captured image. The relative position and orientation of the image-capturing apparatus (50) with respect to the measurement object is then calculated using the selected projection geometric features and image geometric features corresponding to the selected projection geometric features detected in the captured image.

Claims

1. A measurement apparatus for measuring relative position or orientation of an image-capturing apparatus adapted to capture images of one or more measurement objects with respect to a measurement object, wherein the measurement apparatus comprises:

an image acquiring unit configured to acquire a captured image from the image-capturing apparatus;

a projection unit configured to project geometric features of a 3D model of the measurement object onto the captured image based on a position and orientation of the image-capturing apparatus to obtain projection geometric features;

a selecting unit configured to select projection geometric features to be used in calculation of the position or orientation from the projection geometric features obtained by the projection unit based on distances with respect to the projection geometric features in the captured image; and

a calculating unit configured to calculate the relative position or orientation of the image-capturing apparatus with respect to the measurement object using the projection geometric features selected by the selecting unit and image geometric features corresponding to the selected projection geometric features detected in the captured image.

2. The apparatus according to claim 1, wherein the projection unit is adapted to obtain projection geometric features by projecting line segments constituting a 3D model of a measurement object and corresponding to image geometric features that can be detected in a captured image onto the captured image.

3. The apparatus according to claim 1, wherein the calculating unit comprises:

a setting unit configured to set up, for the selected projection geometric features, one or more points in the captured image and obtain a search direction at each point;

and a search unit configured to search the captured image for image geometric features based on the points and the direction of search set up by the setting unit.

4. The apparatus according to claim 1, wherein the projection geometric features are line segments and the selecting unit is configured to select a projection geometric feature if the projection geometric feature is at least a predetermined distance away from at least one previously determined projection geometric feature.

5. The apparatus according to claim 1, which further comprises a geometric feature sort unit configured to set the sequence of processing by the selecting unit for a plurality of projection geometric features of the measurement object obtained by the projection unit.

6. The apparatus according to claim 5, wherein the geometric feature sort unit is configured to sort the projection geometric features into an order based on the lengths of the projection geometric features in the captured image.

7. The apparatus according to claim 5, wherein the geometric feature sort unit is configured to sort the projection geometric features into an order based on measure of an ability to detect the corresponding image geometric features in the captured image.

8. The apparatus according to claim 1, wherein the projection geometric features are line segments and the selecting unit is configured to select a projection geometric feature if its length in the captured image is greater than a predetermined threshold.

9. A control method for a measurement apparatus measuring the relative position or orientation of an image-capturing apparatus adapted to capture images of one or more measurement objects with respect to a measurement object, wherein the method comprises:

acquiring a captured image from the image-capturing apparatus;

projecting respective geometric features of a 3D model of the measurement object onto the captured image based on a position and orientation of the image-capturing apparatus to obtain projection geometric features;

selecting projection geometric features to be used in calculation of the position or orientation from the projection geometric features obtained based on distances with respect to the projection geometric features in the captured image; and

calculating the relative position or orientation of the image-capturing apparatus with respect to the measurement object using the projection geometric features selected and image geometric features corresponding to the selected projection geometric features detected in the captured image.

10. The method according to claim 9, wherein the projecting of respective geometric features involves obtaining projection geometric features by projecting line segments constituting a 3D model of a measurement object and corresponding to image geometric features that can be detected in the captured image onto the captured image.

11. The method according to claim 9, wherein the calculation of the relative position or orientation comprises:

setting, for the obtained projection geometric features, one or more points in the captured image and obtaining a search direction at each point;

and searching, based on the points and the direction of search set up, the captured image for image geometric features.

12. The method according to claim 11, wherein the projection geometric features are line segments and the selection of projection geometric features involves selecting a projection geometric feature if the projection geometric feature is at least a predetermined distance away from at least one previously determined projection geometric feature.

13. The method according to claim 9, which further comprises setting the sequence of processing during the selection of projection geometric features for a plurality of projection geometric features of the measurement object obtained.

14. The method according to claim 13, wherein setting of the sequence of processing comprises sorting the projection geometric features into an order based on the length of the projection geometric features in the captured image.

15. The method according to claim 13, wherein the setting of the sequence of processing comprises sorting the projection geometric features into an order based on a measure of the ability to detect the corresponding image geometric features in the captured image.

16. The method according to claim 9, wherein the projection geometric features are line segments and the selection of projection geometric features comprises selecting a projection geometric feature if its length in the captured image is greater than a predetermined threshold.

17. A computer-readable storage medium storing a program for causing a measuring apparatus to perform a control method for measuring the relative position or orientation of an image-capturing apparatus, which image-capturing apparatus is adapted to capture images of one or more measurement objects with respect to a measurement object, the method comprising:

acquiring a captured image from the image-capturing apparatus;

projecting respective geometric features of a 3D model of the measurement object onto the captured image based on a position and orientation of the image-capturing apparatus to obtain projection geometric features;

selecting projection geometric features to be used in calculation of the position or orientation from the projection geometric features obtained in the projecting step based on distances with respect to the projection geometric features in the captured image; and

calculating the relative position or orientation of the image-capturing apparatus with respect to the measurement object using the projection geometric features selected in the selection step and image geometric features corresponding to the selected projection geometric features detected in the captured image.

18. A measurement apparatus for measuring relative position or orientation of an image-capturing apparatus adapted to capture images of one or more measurement objects with respect to a measurement object, wherein the measurement apparatus comprises:

image acquiring means for acquiring a captured image from the image-capturing apparatus;

projection means for projecting geometric features of a 3D model of the measurement object onto the captured image based on a position and orientation of the image-capturing apparatus to obtain projection geometric features;

selecting means for selecting projection geometric features to be used in calculation of the position or orientation from the projection geometric features obtained by the projection means based on distances with respect to the projection geometric features in the captured image; and

calculating means for calculating the relative position or orientation of the image-capturing apparatus with respect to the measurement object using the projection geometric features selected by the selecting means and image geometric features corresponding to the selected projection geometric features detected in the captured image.