SE515134C2 - System and method of camera positioning in a virtual studio - Google Patents

Abstract

The present invention refers to a method and a system in a virtual studio for optical non-contact positioning of at least one camera (11, 31) in a volume by means of one or more tracking cameras (18, 38). The camera (11, 31) is equipped with a marker unit (19, 39), which is visible at least from one tracking camera (18, 38), which generates a signal containing information about the position and/or orientation of the camera (11, 31). Said information is transferred to a unit for further processing with respect to a second set of information for generating an essentially coherent main information.

Description

25 30 515 134 _2 * A second system uses an additional camera attached to the TV camera and is aimed at the ceiling of the study where coded discs that can be detected by the camera have been mounted and your image document indicates the position of the TV camera.

BRIEF DESCRIPTION OF THE INVENTION The object of the present invention is to provide a system for non-contact position control of at least one camera in a volume in real time in a very simple and accurate manner.

The system according to the invention enables unhindered movement of the TV camera over a surface without affecting the generation of position and orientation parameters.

This information has been solved in that the initially mentioned camera is provided with a marker unit, which is visible at least from a tracking hinge. The tracking mainer generates a signal containing information about the position of the camera and / or the orientation of which information is transmitted to a unit for further processing with respect to a second amount of information relevant to the studio constituting a substantially coherent main information.

In a preferred embodiment, the tracking camera is a CCD equipped camera and operates within the IR range. Preferably, the tracking camera communicates with a computer unit, which is also connected to the camera for positioning the camera.

The tracking cameras are arranged to measure the marker unit, whereby information about the degrees of freedom of the marker unit is determined. The position of the camera is determined relative to a global coordinate system belonging to the volume.

According to the method according to the invention for non-contact position determination of at least one camera in a volume by means of one or two tracking cameras, the method comprises the steps of providing the camera with a marker unit visible at least from one of the tracking cameras, and that by means of the tracking camera generate a signal containing information about the camera's degrees of freedom.

The method further includes the step of measuring the camera's image capture unit related and the generated degrees of freedom are related to the measurement.

Advantageously, measurement of the tracking cores can be done according to an automatic method in which a special cursor unit is attached to the TV mount's object mount, after which the tracking canary system relatively measures the cursor unit relative to the cursor arranged on the TV camera during the entire measurement process.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described below with reference to exemplary embodiments shown in the accompanying drawings, in which: Fig. 2 shows very schematically a system according to the invention. Fig. 2 schematically shows a marker unit which can be used in a system according to the invention.

DESCRIPTION OF THE EMBODIMENT According to the invention, a camera system is used to measure the position and orientation of one or more of your TV / video cameras in a studio (or a place where film recording is performed). Each TV core to be tracked / positioned is provided with at least one marker and measured by means of a real-time arrangement specific to the system. Information about the TV camera's position and orientation was then transmitted in real time to a computer system that controls the virtual camera, ie. a camera that in the virtual studio corresponds to the real camera. The term "TV camera" is used here for the sake of simplicity and means the film studio cameras that produce real images and can consist of any type of camera. The camera can also be rigid or movable and operated manually or remotely controlled (robot).

Fig. 1 shows a film studio where an object 10, in this case a car, is filmed by means of a camera II (TV or video camera). The system further comprises at least one computer unit 12 for generating images 13 which can constitute the background or prop, so-called a virtual studio. These images can also be stored in some memory and retrieved when needed. In addition, the system comprises a second computer unit 14 for effecting an assembly 15, i.e. combine the images 16 and 17 obtained from the camera 11 and the computer unit 12. Of course, the computer unit 12 and 14 can be integrated in one and the same computer unit.

It is also possible to transmit information from multiple TV cameras that generate “real” images and merge them into the computer 14.

The system also comprises a number of "tracking cameras" 18 and at least one cursor unit 19 arranged on the TV camera 11, which is visible from at least one of the cameras, preferably from at least three of the cameras 18. The tracking cameras 18 preferably consist of IR-based CCD cameras. These cameras can be equipped with IR generating devices or communicate with, e.g. IR flashes. The cursor unit consists of one or your cursors provided with a reflecting surface. Active markers (coded or uncoded) that generate IR (or other type of light) can also be used.

To detect all degrees of brightness of the TV camera, use 3 or 2 of your CCD cameras 18.

Preferably, the 50 and 60 Hz CCD cameras operate in sync with the studio synchronization.

However, this is not a limitation. The function of a CCD camera is believed to be known to one skilled in the art and is not described in detail herein.

In one embodiment, the system may comprise only a tracking camera and a marker arranged on the TV camera, positioning taking place in accordance with the Swedish patent, no. 9700066-5, described method.

Fig. 2 schematically shows a marker unit 19 consisting of 6 spherical or partially spherical markers 20 arranged on the ends of supporting rods 21 constituting a stand. The markers are arranged at different levels to enable more accurate determination of its and thus the position and orientation of the camera. It is also possible to use a marker unit comprising a marker or a threshold value passphrase in 515 134 _5__ markers. The size of the markers in the marker unit can also vary. Of course, the invention is not limited to this drying of the marker unit and different embodiments may occur.

In a preferred embodiment, the position determination takes place by each CCD camera detecting IR reactions (or light) from the markers. The camera includes optical elements, which project the image of the cursor onto a CCD disc in the camera. The surface of the CCD unit is then scanned and the image signals comprising pixel information are converted into a suitable video signal by means of a conversion unit, which may be integrated in the CCD unit. The video signal representing the image lines is then sent serially or in parallel to a processing unit. The processing unit digitizes the received video signal, for example an A / D converter is used. This signal can also be digitized in the camera.

The pixels are arranged in lines by means of a low pass filter to deliver a partially continuous signal, which can be processed as an analog signal. However, in the preferred embodiment, each pixel is measured individually and from the measured value a value is interpolated which determines when a The digitized signal is transmitted to a comparator unit which interpolates individually plotted values around the predetermined threshold value, also called a memory level . As described above, the purpose is to determine when the amplitude of the signal exceeds the threshold value. Each passage represents a start and stop coordinate of each segment with a high resolution, which can be about 30 times the number of pixels in a row. In a calculation unit, the center point is calculated.

For a circular marker, the arena of the image can be calculated. The result can then be transformed into an interface unit for further transfer to the computer unit, in which the calculated values (center point, ie x-, y-, z-position by measuring with two cameras, area diameter) can be used to show the position of the cursor .

By continuously scanning the markers, their movement can be detected. Camera rotations and 10 15 20 25 515 134 -6r- movements are detected by the markers having different levels and distances from each other and the camera.

The CCD cameras 18 are arranged to measure the marker units and calculate, e.g. 6 degrees of freedom for each cursor unit (each cursor x-, y-, z-coordinate, pan, tilt and roll). Before recording, the TV camera's image capture device, e.g. CCD measured and the six degrees of freedom generated are related to this. Each camera may include a computer unit for calculating the positions of the markers; alternatively, a central unit or computer unit 14 may be used to perform image analysis and / or computational work. The signal from the CCD cameras (processed or unprocessed) was then sent to the computer 14 for use in assembly.

The marker unit 19 is preferably arranged on the upper side of the TV camera and the CCD cameras are hung from a stand or the ceiling facing the camera.

Preferably, the CCD cameras are calibrated in a volume (studio) specific coordinate system.

Thus, the calculated degrees of freedom of the TV camera's image unit can be given in a global (in kïïordineïtqsyštërrfšpeci fi líifór volume.

During calibration, the CCD cameras can be measured according to an automatic procedure in which a special cursor unit is attached to the TV camera's object mount, after which the CCD camera system (or tracking camera system) measures the cursor unit relative to the cursor mounted on the TV camera throughout the measurement process.

While we have illustrated and described only a preferred embodiment of the invention, it will be appreciated that your variations and modifications may occur within the scope of the appended claims. 10 15 515 REFERENCE DESIGNATIONS r- fl \ O 20 object camera computer unit greek computer unit montage image image tracking camera cursor unit cursor bar 134

Claims (9)

1.0 20 25 30 515 134 _8, _ PATENT REQUIREMENTS A system in a virtual studio and intended for non-contact position determination of at least one camera (11) in a volume by means of one or more tracking cameras (18), characterized in that the camera (1 1) is provided with a marker unit (19), which is visible at least from a tracking camera (18), which tracking camera generates a signal containing information about the position and / or orientation of the camera (1 1), which information is reduced to a unit for a further relevant amount of information constituting a substantial processing with respect to a second for the studio coherent main information. 2. A system according to claim 1, characterized in that the tracking camera is a CCD equipped camera. 3. - äëtßfaf-nliat P fl tæëf fl v år r is characterized by the fact that the tracking chain operates within the IR range. System according to claim 1, characterized in that the tracking camera communicates with a computer unit (14), which is also connected to the camera (11) for positioning the camera (11). System according to claim 1, characterized in that the tracking channels (18) are arranged to measure in the marker unit (19), information on the degrees of freedom of the marker unit being taken into account. 6. A system according to claim 1, characterized in that the position of the camera is determined relative to a global coordinate system belonging to the volume. In a virtual studio, a method for determining the position position of at least one camera (11) in a volume by means of one or more tracking cameras (18), characterized in that the method comprises the steps of - providing the camera (II) with a marker unit (19) visible at least from one of the tracking cameras (18), and - generating a signal containing information about the degrees of freedom of the camera (l 1) by the tracking camera, and - transmitting the information to a unit for further processing with respect to a second amount of information relevant to the studio constituting a substantially coherent main information. A method according to claim 7, for measuring the camera (l 1) image capture unit relate and the generated degrees of unity are related to the measurement. Method according to claim 7, characterized in that measurement of the tracking cameras can take place according to an automatic method in which a special cursor unit is attached to the object mount of the TV camera, after which the CCD camera system tracking camera system relatively measures the cursor unit relative to the cursor arranged on the TV camera. . The present invention relates to a method and system in a virtual studio and intended for non-contact position determination of at least one camera (11) in a volume by means of one or two tracking cores (18). The camera (11) is provided with a marker unit (19), which is visible at least from a tracking camera (18). The tracking camera generates a signal containing information about the position and / or orientation of the camera (11), which information is transmitted to a unit for further processing with respect to a second amount of information relevant to the studio constituting a substantially coherent main information. (Fig. 1)