Object detection and tracking with variable-field illumination devices

• US 9,285,893 B2
• Filed: 01/18/2013
• Issued: 03/15/2016
• Est. Priority Date: 11/08/2012
• Status: Active Grant

• Current Assignee: Lmi Liquidating Co., LLC
• Original Assignee: Leap Motion Incorporated (Ultraleap Limited)
• Inventors: Holz, David Samuel
• Primary Examiner(s): RAHAMAN, MOHAMMED S
• Application Number:
  US13/744,810
• Publication Number:
  US 20140125813A1
• Time in Patent Office: 1,152 Days
• Field of Search: 348/169, 348 40- 60
• US Class Current: 1/1
• CPC Class Codes: G06F 3/017 Gesture based interaction, e.g. based on a set of recognized hand gestures interaction based on gestures traced on a digitiser G06F3/04883
• CPC Class Codes: G06F 3/0304 Detection arrangements using opto-electronic means constructional details of pointing devices not related to the detection arrangement using opto-electronic means G06F3/033; optical digitisers G06F3/042
• CPC Class Codes: G06V 10/141 Control of illumination
• CPC Class Codes: G06V 10/28 Quantising the image, e.g. histogram thresholding for discrimination between background and foreground patterns
• CPC Class Codes: G06V 40/107 Static hand or arm

Abstract

Imaging systems and methods optimize illumination of objects for purposes of detection, recognition and/or tracking by tailoring the illumination to the position of the object within the detection space. For example, feedback from a tracking system may be used to control and aim the lighting elements so that the illumination can be reduced or increased depending on the need.

Claims

1. An object illumination and image capture system part of a person-machine interface comprising:

a camera having a fixed field of view;

a plurality of individually controllable lighting elements directed toward the field of view, at least some of the lighting elements having different beam angles, including at least one wide-beam lighting element and one or more narrow-beam lighting elements; and

a controller coupled to the camera and the light sources and configured to;

operate the camera to capture a sequence of images including a control object arriving at and moving in the field of view;

operate the lighting elements to illuminate the field of view with the wide-beam lighting element while detecting the arrival of the control object and to activate the narrow-beam lighting elements and follow the control object with the narrow-beam lighting elements as it moves within the field of view; and

illuminate the moving control object using the narrow-beam lighting elements with sufficient intensity to facilitate detection of control gestures by the control object within the field of view.

2. The system of claim 1 wherein a plurality of lighting elements are narrow-beam lighting elements.

3. The system of claim 2 wherein the narrow-beam lighting elements have a beam angle of approximately 60°

.

4. The system of claim 2 wherein the at least one wide-beam lighting element has a beam angle of approximately 120°

.

5. The system of claim 2 wherein the controller is configured to track the object and activate different ones of the narrow-beam lighting elements to maintain the object in illumination as it moves.

6. The system of claim 5 wherein the controller is configured to deactivate lighting elements not necessary to illuminate the object.

7. The system of claim 2 wherein the controller is configured to steer the narrow-beam lighting elements to maintain the object in illumination by at least one such element as the object moves.

8. The system of claim 1 wherein the controller is configured to analyze images from the camera to predict a trajectory of the object and to activate or steer lighting elements in accordance with the predicted trajectory.

9. An object illumination and image capture system part of a person-machine interface comprising:

a camera having a fixed field of view;

a plurality of individually controllable lighting elements directed toward the field of view and controllable optics associated with at least some of the lighting elements, the optics controllably altering a beam angle of the associated lighting elements; and

a controller coupled to the camera and the light sources and configured to;

operate the camera to capture a sequence of images including a control object arriving at and moving in the field of view; and

operate the lighting elements and the optics to illuminate the field of view with at least one broad beam of light while detecting arrival of the control object and with one or more narrower beams of light while following the control object as it moves within the field of view; and

illuminate the moving control object using the one or more narrower beams of light with sufficient intensity to facilitate application of object axis detection to the sequence of images of the control object to detect control gestures by the control object within the field of view.

10. The system of claim 9 wherein the optics are tunable lenses.

11. The system of claim 10 wherein the controller controls the optics to vary a beam angle of a lighting element and a drive current to vary an output luminance of the lighting element.

12. A method of object illumination and image capture as a part of a person-machine interface used with a camera having a fixed field of view and a plurality of lighting elements oriented towards the field of view, at least some of the lighting elements having different beam angles, including at least one wide-beam lighting element and one or more narrow-beam lighting elements, the method comprising the actions of:

operating the camera to capture a sequence of images including a control object arriving at and moving in the field of view; and

operating the lighting elements to illuminate the field of view with the wide-beam lighting element while detecting the arrival of the control object and to activate the narrow-beam lighting elements and follow the control object with the narrow-beam lighting elements as it moves within the field of view; and

illuminate the moving control object using the one or more narrow-beam lighting elements with sufficient intensity to facilitate application of object axis detection to the sequence of images of the control object to detect control gestures by the control object within the field of view.

13. The method of claim 12 wherein the lighting elements include a plurality of narrow-beam lighting elements.

14. The method of claim 13 wherein the narrow-beam lighting elements have a beam angle of approximately 60°

.

15. The method of claim 13 wherein the at least one wide-beam lighting element has a beam angle of approximately 120°

.

16. The method of claim 13 wherein the object is tracked and different ones of the narrow-beam lighting elements are activated to maintain the object in illumination as it moves.

17. The method of claim 16 further comprising the step of deactivating lighting elements not necessary to illuminate the object.

18. The method of claim 13 further comprising the step of steering the narrow-beam lighting elements to maintain the object in illumination by at least one such element as the object moves.

19. The method of claim 12 further comprising the step of analyzing images from the camera to predict a trajectory of the object and activating or steering lighting elements in accordance with the predicted trajectory.

20. A method of object illumination and image capture as a part of a person-machine interface used with a camera having a fixed field of view and a plurality of individually controllable lighting elements oriented towards the field of view and controllable optics associated with at least some of the lighting elements, the optics controllably altering a beam angle of the associated lighting elements, including at least one wide-beam lighting element and one or more narrow-beam lighting elements, the method comprising the actions of:

operating the camera to capture a sequence of images including a control object arriving at and moving in the field of view;

operating the lighting elements and the optics to illuminate the field of view with the wide-beam lighting element while detecting the arrival of the control object and to activate the narrow-beam lighting elements and follow the control object with the narrow-beam lighting elements as it moves within the field of view; and

illuminate the moving control object using the one or more narrow beam lighting elements with sufficient intensity to facilitate detection of control gestures by the control object within the field of view.