Automatic camera head and operation method

1. An automatic camera head for panning and tilting a video camera, comprising a base, an intermediate element connected to said base and rotatable relative to said base about a pan rotation axis, a camera holder connected to said intermediate element and rotatable relative to said intermediate element about a tilt rotation axis orthogonal to the pan rotation axis, a pan actuator arranged to turn the intermediate element about the pan rotation axis, a tilt actuator arranged to turn the camera holder about the tilt rotation axis, wherein the pan actuator and/or the tilt actuator include DC brushless motors driving the intermediate element respectively the camera holder directly, the automatic camera head having at least one ring actuator arranged to act on a ring control of an objective of the camera, wherein said ring control is one of: zoom, iris, and focus and a control unit arranged to execute a calibration process with the steps of:

moving the ring control by the ring actuator;

determining limit angles in the ring control;

determining the field of view of the objective at a plurality of positions of the ring control.

2. The automatic camera head of claim 1 , wherein determining the field of view of the objective includes:

take at least a first image and a second image of a scene by the camera at different pan and/or tilt angles;

identify and pair key features in the first and second image;

determine the field of view based on the separation of paired key features in the first and second images.

3. An automatic camera head for panning and tilting a video camera, comprising a base, an intermediate element connected to said base and rotatable relative to said base about a pan rotation axis, a camera holder connected to said intermediate element and rotatable relative to said intermediate element about a tilt rotation axis orthogonal to the pan rotation axis, a pan actuator arranged to turn the intermediate element about the pan rotation axis, a tilt actuator arranged to turn the camera holder about the tilt rotation axis, wherein the pan actuator and/or the tilt actuator include DC brushless motors driving the intermediate element respectively the camera holder directly having a control unit arranged to execute a dynamic calibration process with the steps of:

cause a change of angle of the pan rotation axis and/or of the tilt rotation axis,

capturing video data during the change of angle, by a video camera mounted on the camera holder,

determine an allowed range of dynamic parameters for the pan rotation axis and/or the tilt rotation axis based on the captured video data.

4. An automatic camera head for panning and tilting a video camera, comprising a base, an intermediate element connected to said base and rotatable relative to said base about a pan rotation axis, a camera holder connected to said intermediate element and rotatable relative to said intermediate element about a tilt rotation axis orthogonal to the pan rotation axis, a pan actuator arranged to turn the intermediate element about the pan rotation axis, a tilt actuator arranged to turn the camera holder about the tilt rotation axis, wherein the pan actuator and/or the tilt actuator include motors driving the intermediate element respectively the camera holder, the camera head having at least one ring actuator arranged to act on a ring control of an objective of the camera and a control unit arranged to execute a calibration process with the steps of:

moving the ring control by the ring actuator;

determining limit angles in the ring control;

determining the field of view of the objective at a plurality of positions of the ring control, wherein

determining the field of view of the objective includes:

take at least a first image and a second image of a scene by the camera at different pan and/or tilt angles;

identify and pair key features in the first and second image;

determine the field of view based on the separation of paired key features in the first and second images.

5. An automatic camera head for panning and tilting a video camera, comprising a base, an intermediate element connected to said base and rotatable relative to said base about a pan rotation axis, a camera holder connected to said intermediate element and rotatable relative to said intermediate element about a tilt rotation axis orthogonal to the pan rotation axis, a pan actuator arranged to turn the intermediate element about the pan rotation axis, a tilt actuator arranged to turn the camera holder about the tilt rotation axis, wherein the pan actuator and/or the tilt actuator include motors driving the intermediate element respectively the camera holder, the camera head having a control unit arranged to execute a dynamic calibration process with the steps of:

cause a change of angle of the pan rotation axis and/or of the tilt rotation axis,

capturing video data during the change of angle, by a video camera mounted on the camera holder,

determine an allowed range of dynamic parameters for the pan rotation axis and/or the tilt rotation axis based on the captured video data.

6. An automatic camera head for panning and tilting a video camera, comprising a base, an intermediate element connected to said base and rotatable relative to said base about a pan rotation axis, a camera holder connected to said intermediate element and rotatable relative to said intermediate element about a tilt rotation axis orthogonal to the pan rotation axis, a pan actuator arranged to turn the intermediate element about the pan rotation axis, a tilt actuator arranged to turn the camera holder about the tilt rotation axis, wherein the pan actuator and/or the tilt actuator include DC brushless motors driving the intermediate element respectively the camera holder directly or via a strain-wave reduction gear, the automatic camera head comprising at least one ring actuator arranged to act on a ring control of an objective of the camera, wherein said ring control is one of: zoom, iris, and focus, and a control unit arranged to execute a calibration process with the steps of:

moving the ring control by the ring actuator;

determining limit angles in the ring control;

determining the field of view of the objective at a plurality of positions of the ring control.

7. The automatic camera head of claim 6 , including a torque measurement unit delivering a signal indicative of the torque applied to the ring control.

8. The automatic camera head of claim 6 , including angle encoders delivering a signal indicative of a pan angle between the base and the intermediate member and/or of a tilt angle between the intermediate member and the camera holder.

9. The automatic camera head of claim 6 , comprising a detachable rigging platform attachable to the camera and releasably connected to the camera holder, wherein the has ring actuator is attached to the rigging platform.

10. An automatic camera head for panning and tilting a video camera, comprising a base, an intermediate element connected to said base and rotatable relative to said base about a pan rotation axis, a camera holder connected to said intermediate element and rotatable relative to said intermediate element about a tilt rotation axis orthogonal to the pan rotation axis, a pan actuator arranged to turn the intermediate element about the pan rotation axis, a tilt actuator arranged to turn the camera holder about the tilt rotation axis, wherein the pan actuator and/or the tilt actuator include DC brushless motors driving the intermediate element respectively the camera holder directly or via a strain-wave reduction gear, the automatic camera head comprising a control unit arranged to execute a calibration process with the steps of:

take at least a first image and a second image of a scene by the camera at different pan and/or tilt angles;

identify and pair key features in the first and second image;

determining a field of view of the camera based on the separation of paired key features in the first and second images.

11. The automatic camera head of claim 10 , including angle encoders delivering a signal indicative of a pan angle between the base and the intermediate member and/or of a tilt angle between the intermediate member and the camera holder.

12. The camera head of claim 10 , comprising a communication interface and an input device arranged to set the camera head in a manual state in which the motors produce no torque and in which directives received from the communication interface are ignored.

13. An automatic camera head for panning and tilting a video camera, comprising a base, an intermediate element connected to said base and rotatable relative to said base about a pan rotation axis, a camera holder connected to said intermediate element and rotatable relative to said intermediate element about a tilt rotation axis orthogonal to the pan rotation axis, a pan actuator arranged to turn the intermediate element about the pan rotation axis, a tilt actuator arranged to turn the camera holder about the tilt rotation axis, wherein the pan actuator and/or the tilt actuator include DC brushless motors driving the intermediate element respectively the camera holder directly or via a strain-wave reduction gear, having a control unit arranged to execute a dynamic calibration process with the steps of:

cause a change of angle of the pan rotation axis and/or of the tilt rotation axis,

capturing video data during the change of angle, by a video camera mounted on the camera holder,

determine an allowed range of dynamic parameters for the pan rotation axis and/or the tilt rotation axis based on the captured video data.

14. The automatic camera head of claim 13 , including angle encoders delivering a signal indicative of a pan angle between the base and the intermediate member and/or of a tilt angle between the intermediate member and the camera holder.

15. The camera head of claim 13 , comprising a communication interface and an input device arranged to set the camera head in a manual state in which the motors produce no torque and in which directives received from the communication interface are ignored.