DETERMINING DISTANCE BETWEEN AN OBJECT AND A CAPTURE DEVICE BASED ON CAPTURED IMAGE DATA

• US 20160055395A1
• Filed: 11/04/2015
• Published: 02/25/2016
• Est. Priority Date: 09/27/2013
• Status: Active Grant

• Current Assignee: Kofax Incorporated
• Original Assignee: Kofax Incorporated
• Inventors: Macciola, Anthony, Ma, Jiyong, Shustorovich, Alexander, Amtrup, Jan W., Thrasher, Christopher
• Granted Patent: US 9,946,954 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 2207/30176 Document
• CPC Class Codes: G06T 3/00 Geometric image transformations in the plane of the image
• CPC Class Codes: G06T 5/80 Geometric correction
• CPC Class Codes: G06T 7/60 Analysis of geometric attributes

Abstract

In various embodiments, methods, systems, and computer program products for determining distance between an object and a capture device are disclosed. The distance determination techniques are based on image data captured by the capture device, where the image data represent the object. These techniques improve the function of capture devices such as mobile phones by enabling determination of distance using a single lens capture device, and based on intrinsic parameters of the capture device, such as focal length and scaling factor(s), in preferred approaches. In some approaches, the distance estimation may be based in part on a priori knowledge regarding size of the object represented in the image data. Distance determination may be based on a homography transform and/or reference image data representing the object, a same type or similar type of object, in more approaches.

Claims

1. A method, comprising:

determining a distance between an object and a capture device based on image data captured by the capture device, wherein the image data represent the object.

2. The method as recited in claim 1, wherein determining the distance comprises estimating a normalized homography matrix {tilde over (H)}.

3. The method as recited in claim 1, comprising determining a capture device focal length using an API call to the capture device.

4. The method of claim 1, wherein the determining is based at least in part on a size of the object.

5. The method as recited in claim 1, wherein the determining is not based on a size of the object.

6. The method as recited in claim 1, wherein the determining is based on a translation vector of the object relative to the capture device.

7. The method as recited in claim 1, wherein the determining is based at least in part on one or more intrinsic capture device parameters.

8. The method as recited in claim 7, wherein the determining is based on a capture device intrinsic parameter matrix A.

9. The method as recited in claim 8, wherein:

10. The method as recited in claim 7, comprising determining one or more of the intrinsic capture device parameters based at least in part on a capture device focal length and a size of the object;

wherein the intrinsic capture device parameters comprise scaling factors;

dx and dy;

wherein the capture device focal length is determined using an API call to the capture device; and

wherein the size of the object is known a priori.

11. The method as recited in claim 7, comprising determining one or more of the intrinsic capture device parameters based at least in part on a capture device focal length and a size of the object;

wherein the intrinsic capture device parameters comprise a scaling factor σ

in a homography transform H;

wherein the capture device focal length is determined using an API call to the capture device; and

wherein the size of the object is known a priori.

12. The method as recited in claim 7, the intrinsic capture device parameters comprising one or more of a focal length corresponding to a type of the capture device and one or more scaling factors corresponding to the type of the capture device.

13. The method as recited in claim 12, comprising normalizing one or more of the scaling factors.

14. The method as recited in claim 13, wherein the normalizing is based on a homography transform H;

wherein H=σ

A(r₁, r₂, t); and

wherein σ

is a scaling factor constant.

15. The method as recited in claim 14, wherein determining the distance comprises estimating H.

16. The method as recited in claim 15, wherein H satisfies an expression λ

p_i=HP_i′

, wherein

λ

=a focal distance between a three-dimensional reference coordinate position (X, Y, Z) and a corresponding reference coordinate position of a capture device;

p_i=(x_i, y_i,

     1)^T;

P′

_I=(X_i, Y_i,

     1)^T; and

i is a respective index feature of a point p or P′

in a corresponding image.

17. A system, comprising:

a processor configured to execute logic; and

logic configured to determine a distance between an object and a capture device based on image data captured by the capture device, the image data representing the object.

18. The system as recited in claim 17, wherein the logic is configured to determine the distance based at least in part on one or more intrinsic parameters of the capture device.

19. A computer program product comprising a computer readable storage medium having computer readable program code stored thereon, the computer readable program code comprising:

computer readable program code configured to determine a distance between an object and a capture device based on image data captured by the capture device, the image data representing the object.

20. The computer program product as recited in claim 19, wherein the computer readable program code is configured to determine the distance based at least in part on one or more intrinsic parameters of the capture device.