Dynamic camera focusing
Apparatus for focusing a camera having an optic axis, an optic center and a field of view, to image a scene, the apparatus comprising: an illumination system controllable to illuminate substantially any region of interest (ROI) of the scene in the field of view of the camera with a relatively small fiducial spot of light; a ranging system configured to determine a range for the fiducial spot relative to the camera; and a controller that focuses the camera to a distance responsive to the determined range.
1. Apparatus for focusing a camera having an optic axis, an optic center and a field of view, to image a scene, the apparatus comprising:
an illumination system controllable to illuminate substantially any region of interest (ROI) of the scene in the field of view of the camera with a fiducial spot of light;
a position sensing device that determines a direction relative to the camera optic axis along which the illumination system illuminates the ROI with the fiducial spot of light;
a ranging system configured to determine a range for the fiducial spot relative to the camera; and
a controller that focuses the camera to a distance responsive to the determined range.
2. Apparatus according to claim 1 comprising a display screen that displays an image of the scene and a location in the scene illuminated by the fiducial spot of light.
3. Apparatus according to claim 1 wherein the controller is configured to process the range to provide a distance to which to focus the camera that is substantially equal to a scalar product of a vector from the camera optic center to the fiducial spot with a unit vector coincident with the camera optic axis.
4. Apparatus according to claim 1 and comprising a controller, manually operable to aim the illumination system to illuminate a desired ROI in the scene.
5. Apparatus according to claim 4 wherein the manually operable controller is operable to control the apparatus to determine the range for the fiducial spot when the ROI is illuminated therewith.
6. Apparatus according to claim 4 wherein the manually operable controller is operable to focus the camera when the range is determined.
7. Apparatus according to claim 6 wherein the manually operable controller is operable to lock the camera focus.
8. Apparatus according to claim 4 wherein the manually operable controller is operable to control the camera to acquire an image of the scene when the camera is focused.
9. Apparatus according to claim 4 wherein the controller comprises a rotatable roller-ball, finger-operated to provide a function of the controller.
10. Apparatus according to claim 4 wherein the controller comprises a touch sensitive screen finger-operated to provide a function of the controller.
11. Apparatus according to claim 1 wherein the light is non-visible light.
12. Apparatus according to claim 1 wherein a direction along which the illumination system illuminates the ROI is not parallel to the camera optic axis.
13. Apparatus according to claim 1 wherein the illumination system encodes light it uses to provide a fiducial spot to distinguish its fiducial spot from a fiducial spot provided by an illumination system of another camera.
14. A camera comprising an apparatus according to claim 1 .
15. A method of focusing a camera having an optic axis and optic center to image a scene, the method comprising:
illuminating an off axis region of interest in the scene with a relatively small fiducial spot of light;
determining a range for the fiducial spot relative to the camera; and
focusing the camera responsive to a scalar product of a vector from the camera optic center to the fiducial spot with a unit vector coincident with the camera optic axis.