Optical flow based tilt sensor

• US 20060177103A1
• Filed: 01/06/2006
• Published: 08/10/2006
• Est. Priority Date: 01/07/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: GestureTek Incorporated (Winning Brands Corp.)
• Inventors: Hildreth, Evan
• Granted Patent: US 7,379,566 B2
• Time in Patent Office: Days
• US Class Current: 382/107
• CPC Class Codes: A63F 2300/1087 comprising photodetecting means, e.g. a camera
• CPC Class Codes: G06F 1/1626 with a single-body enclosure integrating a flat display, e.g. Personal Digital Assistants [PDAs]
• CPC Class Codes: G06F 1/1686 the I/O peripheral being an integrated camera
• CPC Class Codes: G06F 2200/1637 Sensing arrangement for detection of housing movement or orientation, e.g. for controlling scrolling or cursor movement on the display of an handheld computer
• CPC Class Codes: G06F 3/0346 with detection of the device orientation or free movement in a 3D space, e.g. 3D mice, 6-DOF [six degrees of freedom] pointers using gyroscopes, accelerometers or tilt-sensors
• CPC Class Codes: G06T 7/269 using gradient-based methods
• CPC Class Codes: G06V 10/17 using hand-held instruments
• CPC Class Codes: G06V 40/20 Movements or behaviour, e.g. gesture recognition recognition of facial expressions G06V40/16
• CPC Class Codes: H04M 1/72427 for supporting games or graphical animations
• CPC Class Codes: H04M 2250/12 including a sensor for measuring a physical value, e.g. temperature or motion telephones including GPS signal receivers H04M2250/10
• CPC Class Codes: H04M 2250/52 including functional features of a camera constructional features concerning the integration of cameras in portable phones H04M1/0264
• CPC Class Codes: H04N 1/00307 with a mobile telephone apparatus constructional features of portable telephone sets H04M1/0202; mobile radio systems H04W84/00
• CPC Class Codes: H04N 1/00323 with a measuring, monitoring or signaling apparatus, e.g. for transmitting measured information to a central location
• CPC Class Codes: H04N 1/00352 Input means H04N1/00411 takes precedence; input arrangements for computers G06F3/00
• CPC Class Codes: H04N 1/00381 Input by recognition or interpretation of visible user gestures manual input means, e.g. digitisers, writing tablets H04N1/00392; gesture input to computers G06F3/017; recognition algorithms G06V40/20
• CPC Class Codes: H04N 2201/0084 Digital still camera
• CPC Class Codes: H04N 2201/0096 Portable devices

Abstract

A method is described for determining a description of motion of a moving mobile camera to determine a user input to an application. The method may involve capturing a series of images from a moving mobile camera and comparing stationary features present in the series of images. Optical flow analysis may be performed on the series of images to determine a description of motion of the moving mobile camera. Based on the determined motion, a user input to an application may be determined and the application may respond to the user input, for example, by updating a user interface of the application.

Claims

1. A method comprising:

capturing images from a moving mobile camera;

determining a description of motion of the moving mobile camera based on the captured images;

providing a user interface to an application on an interface device; and

determining, in an automated manner, a user input to the application based on the determined motion.

2. The method of claim 1 wherein the interface device is physically coupled to the mobile camera.

3. The method of claim 1 wherein the interface device is physically integrated in a device including the mobile camera.

4. The method of claim 1 wherein determining a description of motion is performed in an automated manner.

5. The method of claim 1 wherein determining a description of motion comprises determining one or more of a magnitude and an orientation.

6. The method of claim 1 wherein determining a description of motion of the moving mobile camera comprises calculating rotation of the moving mobile camera in two degrees of freedom.

7. The method of claim 1 wherein determining a description of motion of the moving mobile camera comprises calculating rotation of the moving mobile camera in three degrees of freedom.

8. The method of claim 1 wherein determining a description of motion of the moving mobile camera comprises calculating translation of the moving mobile camera.

9. The method of claim 1 wherein determining a description of motion of the moving mobile camera comprises calculating motion of the moving mobile camera with respect to an initial position of the moving mobile camera.

10. The method of claim 9 wherein the initial position of the moving mobile camera may be re-set by an application.

11. The method of claim 1 wherein determining a description of motion of the moving mobile camera comprises:

determining motion of features within the captured images; and

determining motion of the mobile camera based on the motion of the features.

12. The method of claim 11 wherein determining a description of motion of the moving mobile camera further comprises:

segmenting the features, based on the determined motion of the features, into a set of moving features that are moving with respect to a real-world frame of reference.

13. The method of claim 12 wherein segmenting moving features comprises selecting a set of features covering the largest area and disregarding features not selected.

14. The method of claim 12 wherein segmenting moving features comprises disregarding features that do not have a direction and magnitude similar to a significant set of features.

15. The method of claim 1 wherein determining a description of motion comprises using optical flow.

16. The method of claim 1 wherein determining a description of motion comprises:

extracting features from the captured images;

comparing images to match features present in more than one image;

determining a flow vector for matched features by calculating the displacement in the position of a feature in a current image relative to the position of the feature in a prior image; and

determining the motion of the mobile camera based on the flow vectors determined for the matched features.

17. The method of claim 16 wherein extracting features from the captured images includes detecting at least one of comers and edges.

18. The method of claim 16 wherein comparing images to match features comprises first comparing a block of an image located proximate to the known position of the feature in another image.

19. The method of claim 16 wherein comparing images to match features comprises first comparing images at a low resolution and, conditioned on whether a match is found, comparing images at a higher resolution.

20. The method of claim 16 wherein determining the motion of the mobile camera based on the flow vectors comprises determining the motion of the mobile camera in real-world units by converting the motion determined in image-dependent units.

21. The method of claim 1 wherein:

capturing images comprises capturing a sequence of images, and

determining a description of motion of the moving mobile camera comprises;

determining motion for a first feature visible in a first subset of images within the sequence of images;

determining motion for a second feature visible in a second subset of images within the sequence of images, overlapping partially with the first subset, and the second feature having a fixed physical relationship with the first feature, wherein motion for the second feature is based on the motion for the first feature even though the first feature is not visible in all of the second subset of images; and

determining the description of motion of the moving mobile camera based on the determined motions for the first and second features.

22. The method of claim 1 wherein the user input replicates a tilt sensor function and controls a tilt of an object in an application.

23. The method of claim 1 wherein the user input controls a motion of a ball in an application.

24. The method of claim 1 wherein the user input controls a steering function of a vehicle in an application.

25. The method of claim 1 wherein the user input controls a targeting function of an object in an application.

26. The method of claim 1 wherein the user input controls a navigation function of an object in an application.

27. The method of claim 1 wherein the user input controls a movement of an articulated character in an application.

28. The method of claim 1 wherein the user input controls a movement of particles in a particle simulation application.

29. The method of claim 1 wherein the user input is determined when the magnitude of the determined motion is greater than a threshold magnitude.

30. The method of claim 1 wherein the application is at least one of a game, a tracking application, and a security application.

31. The method of claim 1 wherein the moving mobile camera is physically coupled to a cellular phone.

32. A handheld device comprising:

a camera; and

a processor configured to;

capture images from the camera;

determine a description of motion of the handheld device based on the captured images;

provide a user interface to an application on an interface device; and

determine, in an automated manner, a user input to the application based on the determined motion.

33. The handheld device of claim 32 wherein the processor is further configured to determine a description of motion of the handheld device by:

extracting features from the captured images;

comparing images to match features present in more than one image;

determining a flow vector for matched features by calculating the displacement in the position of a feature in a current image relative to the position of the feature in a prior image; and

determining the motion of the handheld device based on the flow vectors determined for the matched features.

34. A computer readable medium or propagated signal having embodied thereon a computer program, the computer program comprising:

a capturing code segment for capturing images from a moving mobile camera;

a determining code segment for determining a description of motion of the moving mobile camera based on the captured images;

a providing code segment for providing a user interface to an application on an interface device; and

a determining code segment for determining, in an automated manner, a user input to the application based on the determined motion.

35. The medium or signal of claim 34 wherein:

the capturing code segment for capturing images from a moving mobile camera comprises a code segment for capturing a sequence of images, and

the determining code segment for determining a description of motion of the moving mobile camera comprises;

a code segment for determining motion for a first feature visible in a first subset of images within the sequence of images;

a code segment for determining motion for a second feature visible in a second subset of images within the sequence of images, overlapping partially with the first subset, and the second feature having a fixed physical relationship with the first feature, wherein motion for the second feature is based on the motion for the first feature even though the first feature is not visible in all of the second subset of images; and

a code segment for determining the description of motion of the moving mobile camera based on the determined motions for the first and second features.

36. A portable telephone comprising:

a camera, integrally formed in the telephone;

a display, integrally formed in the telephone;

a processing device, physically and communicatively coupled to the camera and the display; and

a computer readable medium, physically and communicatively coupled to the processing device, and including instructions for causing the processing device to perform at least the following;

receiving images captured from the camera,

determining a description of motion of the telephone based on the received images,

providing on the display a user interface to an application,

determining, in an automated manner, a user input to the application based on the description of motion of the telephone, and

providing the user input to the application.

37. The telephone of claim 36 wherein the computer readable medium is an integrated part of the processing device.