Methods and apparatus for absolute and relative depth measurements using camera focus distance

Patent metadata

Field	Value
Publication number	US-11032464-B2
Application number	US-201916669197-A
Country	US
Kind code	B2
Filing date	Oct 30, 2019
Priority date	Jun 5, 2018
Publication date	Jun 8, 2021
Grant date	Jun 8, 2021

Abstract

A depth measuring apparatus includes a camera assembly, a position sensor, and a controller. The camera assembly is configured to capture a plurality of images of a target at a plurality of distances from the target. The position sensor is configured to capture, for each of the plurality of images, corresponding position data associated with a relative distance between the camera assembly and the target. The controller is configured to, for each of a plurality of regions within the plurality of images: determine corresponding gradient values within the plurality of images; determine a corresponding maximum gradient value from the corresponding gradient values; and determine a depth measurement for the region based on the corresponding maximum gradient and the corresponding position data captured for an image from the plurality of images that includes the corresponding maximum gradient.

First claim

What is claimed is:

1. A depth measuring apparatus comprising:
a camera assembly configured to capture a plurality of images of a target at a plurality of distances from the target;
a position sensor configured to capture, for each of the plurality of images, corresponding position data associated with a relative distance between the camera assembly and the target; and
a controller configured to, for each of a plurality of regions within the plurality of images:
determine corresponding gradient values within the plurality of images;
determine a corresponding maximum gradient value from the corresponding gradient values; and
determine a depth measurement for a region of the plurality of regions based on the corresponding maximum gradient value and the corresponding position data captured for an image from the plurality of images that includes the corresponding maximum gradient value.

2. A depth measuring apparatus comprising:
a camera assembly configured to capture a plurality of images of a target at a plurality of distances from the target;
a position sensor configured to capture, for each of the plurality of images, corresponding position data associated with a relative distance between the camera assembly and the target; and
a controller configured to:
determine a corresponding gradient value for each of a plurality of regions within each of the plurality of images;
determine, based on the corresponding gradient value for each of the plurality regions, a corresponding maximum gradient value for each of the plurality of regions; and
determine, based on the corresponding maximum gradient value for each of the plurality of regions and the corresponding position data for each of the plurality of images, a depth measurement for each of the plurality of regions.

3. The depth measuring apparatus of claim 2 , wherein the plurality of images of the target are to be captured by the camera assembly at the plurality of distances from the target by moving at least one of the camera assembly or the target.

4. The depth measuring apparatus of claim 2 , wherein the controller is to determine the corresponding gradient value by applying an image gradient filter to the plurality of images.

5. The depth measuring apparatus of claim 4 , wherein the image gradient filter comprises one or more of an edge detection filter, a Sobel filter, a Prewitt filter, or a Laplace filter.

6. The depth measuring apparatus of claim 2 , wherein the controller is further to determine the depth measurement based on a reference depth, wherein the plurality of regions are measured relative to the reference depth.

7. The depth measuring apparatus of claim 2 , wherein the camera assembly and the target are:
vertically aligned;
horizontally aligned; or
aligned along an angle.

8. The depth measuring apparatus of claim 2 , wherein the controller is to determine a plurality of depth measurements comprising the depth measurement, wherein the plurality of depth measurements are associated with a plurality of adjacent depth levels and a plurality of non-adjacent depth levels.

9. A depth measuring apparatus comprising:
a camera assembly configured to capture a plurality of images of a target at a plurality of distances from the target;
a position sensor configured to capture, for each of the plurality of images, corresponding position data associated with a relative distance between the camera assembly and the target; and
a controller configured to process the plurality of images and the corresponding position data for each of the plurality of images using an image gradient filter to determine a depth measurement for each of a plurality of regions within the plurality of images.

10. The depth measuring apparatus of claim 9 , wherein the plurality of images of the target are to be captured by the camera assembly at the plurality of distances from the target by moving at least one of the camera assembly or the target.

11. The depth measuring apparatus of claim 9 , wherein the controller is to determine a corresponding gradient value for each of the plurality of regions within the plurality of images by applying the image gradient filter to the plurality of images, wherein the controller is to determine a corresponding maximum gradient value for each of the plurality of regions based on the corresponding gradient value for each of the plurality of regions, and wherein the depth measurement is determined based on the corresponding maximum gradient value for each of the plurality of regions.

12. The depth measuring apparatus of claim 11 , wherein the image gradient filter comprises one or more of an edge detection filter, a Sobel filter, a Prewitt filter, or a Laplace filter.

13. The depth measuring apparatus of claim 9 , wherein the controller is further to determine the depth measurement based on a reference depth, wherein the plurality of regions are measured relative to the reference depth.

14. The depth measuring apparatus of claim 9 , wherein the camera assembly and the target are:
vertically aligned;
horizontally aligned; or
aligned along an angle.

15. The depth measuring apparatus of claim 9 , wherein the controller is to determine a plurality of depth measurements comprising the depth measurement, wherein the plurality of depth measurements is associated with a plurality of adjacent depth levels and a plurality of non-adjacent depth levels.

16. A method comprising:
receiving a plurality of images of a target captured by a camera assembly at a plurality of distances from the target;
receiving, for each of the plurality of images, corresponding position data associated with a relative distance between the camera assembly and the target;
determining a corresponding gradient value for each of a plurality of regions within the plurality of images;
determining, based on the corresponding gradient value for each of the plurality of regions, a corresponding maximum gradient value for each of the plurality of regions; and
determining, based on the corresponding maximum gradient value for each of the plurality of regions and the corresponding position data for each of the plurality of images, a depth measurement for each of the plurality of regions.

17. The method of claim 16 , wherein the plurality of images of the target are to be captured by the camera assembly at the plurality of distances from the target by moving at least one of the camera assembly or the target.

18. The method of claim 16 , wherein the determining of the corresponding gradient value is by applying an image gradient filter to the plurality of images.

19. The method of claim 16 , wherein the determining of the depth measurement is further based on a reference depth, wherein the plurality of regions are measured relative to the reference depth.

20. The method of claim 16 further comprising:
determining a plurality of depth measurements comprising the depth measurement, wherein the plurality of depth measurements is associated with a plurality of adjacent depth levels and a plurality of non-adjacent depth levels.

Assignees

• Applied Materials Inc

Inventors

• Celik Ozkan
• Schulze Patricia A
• Freeman Gregory J
• Wirth Paul Z
• Vercesi Tommaso

Classifications

• H04N23/673

  based on contrast or high frequency components of image signals, e.g. hill climbing method · CPC title

• H04N23/67 Primary

  Focus control based on electronic image sensor signals · CPC title

• G06T2207/20024

  Filtering details · CPC title

• G06T7/55

  from multiple images · CPC title

• G06T5/50

  using two or more images, e.g. averaging or subtraction · CPC title