DE102008028014A1 - Method for simultaneous film-recording of e.g. foot ball player, with multiple cameras from multiple directions, during frame photography, involves combining cameras with similar viewing directions and illuminations to directional group - Google Patents

Abstract

The method involves coding lights of light sources i.e. gas discharge lamps, using a multiplexing process by a multiplexer, where the multiplexing process relates to polarization of the light and color of the light. The selection of suitable light portions is used by a demultiplexer at cameras for illumination. The cameras with similar viewing directions and associated illuminations are combined to a directional group. Color filters are arranged in front of the cameras and light sources. An independent claim is also included for an arrangement for simultaneous film recording of an object with multiple cameras from multiple directions.

Description

State of the art:

Movies are often shot with just one camera. Therefore, must the scenes are repeated for the different directions of view to be turned around. This often leads to errors Re-cut (connection error, continuity error). Only at events, which are not (or only very expensive) repeatable, are several Cameras used from different directions (eg live, football, elaborate explosions or blasts). This also applies to productions too, where throughput to the disadvantage of quality in the foreground stands (for example, soaps).

A problem every director can sing a song of:
All difficulties usually arise only because one turns with a camera and the different processes for the different settings are often recorded several times. It could all be so easy if films like football games were shot. 3-4 cameras, one for the long shots, 2 for close-ups (shot / counter-shot) and one for the two. So each process would be recorded only once, you would never remember how to play the process at the last setting ....
... For expensive, complex productions quite a few cameras are used at the same time. These are mostly used from one direction. A decisive argument against the inclusion of feature films a la football is the light. In the case of film, the illumination is always optimized for a specific camera direction. Only then can you optimally model with light and shadow. For the football variant, everything must be uniformly (bright) illuminated so that each of the 3 or 4 recording cameras also has sufficient light available. By the way, TV soaps (like the Lindenstraße) are recorded in this way. The lighting is correspondingly atmospheric.
To ( http://www.movie-college.de/filmschule/filmgestaltung/anschlussfehler.htm ).

moreover are shutters or closures (eg mirror shutter Arriflex, orbital aperture or LCD shutter) known to cameras. The camera ARRIFLEX 435 has a controllable shutter with trigger signal (Input and output).

LCD shutter TFT displays can take less than 10 ms (sometimes 1 ms) have switching times. For pure black / white function (eg shutter) shorter switching times are possible.

For recording stereoscopic videos (3D), the field-sequential 3D method exists:
... What has the interlacing process to do with 3D technology? It first makes it possible to easily record 3D videos. For this one uses all odd lines (first field) for the picture for the left eye and all even lines (second field) for the picture for the right eye (vice versa it goes of course). Almost all commercial 3D video cameras on the market generate such a procuring 3D video signal (also called interlaced or field-sequential 3D). It is important to understand that it is technically a normal video signal, TV and VCR do not notice a difference to a non-3D signal. The viewer on the TV sees everything without 3D images, that is, each left and right perspective with each eye.
Source ( http://pwimmer.gmxhome.de/LoadFrames.html?/3D/3DVideoTechnique.html ).

To be z. For example, the NuView adapter (with LCD shutter and mirror) is used.

It Also gives flat shutter in LCD shutter glasses or switchable Glazing.

common Basic principles of light sources are light bulbs, gas discharge lamps, LEDs, as well as stroboscopes (which also operated quasi-continuously can be) and the sun or daylight.

Metal halide lamps reach over other high-pressure gas discharge lamps one very high color rendering index (at the for film and TV used HMI lamps up to 90). The color temperature is important Feature of light sources.

The Problem in the prior art, as mentioned above, when filming with several cameras (from different directions) in the lighting. Disturbing are usually light sources that represent a backlight. Backlights can dazzle the camera, just annoying be visible or illuminate the (uninteresting) environment the movie object (eg actor or room area) stronger than the (important), what should actually be filmed.

moreover causes the same scene to rotate several times higher Costs, an increased logistical effort and longer Rotation times.

There are also switchable glazings ( "Glaswelt" 7/2003, page 24, part III, 8/2003, page 22 ). These can be found in: Suspended-particle devices SPD (via switchable absorber particles), switchable mirrors (based on metal hydride), polymer-dispersed-liquid-crystal systems PDLC (light-scattering liquid crystals), and thermotropic layers (above threshold temperature - less suitable for high changes guess).

It is the object of the present invention, a method and a Device to imagine, in which a scene or a movie object can be filmed simultaneously from different directions, backlight effects be avoided and simultaneously several (for each one Camera optimal) lighting can be realized.

These Tasks are characterized by those specified in the claims Characteristics solved.

Description of the invention

The The basic idea of the invention is the respective inappropriate light sources Invisible for the respective camera or camera group to darken. These (counter) light sources can be used in the Also referred to as undesirable, inappropriate or disturbing become.

There Cameras looking in a similar direction often need the same or similar optimal lighting, these cameras are grouped into a group (direction group), so like the associated single light sources as well.

The Hiding does not have to refer to all light sources (some may therefore always remain visible) or there must be no (almost) completely hide the unwanted light sources be achieved.

The simultaneous films of the same scene or object from different Directions does not have to take place simultaneously in the technical sense, since the actual image acquisition (eg when using shutters) can be asynchronous. Simultaneously or temporally parallel means that the same process can be absorbed in one go. It can (optional) the individual images (eg by a few milliseconds) against each other be staggered, d. H. the exposure process the frames takes place asynchronously.

All Embodiments are comparable to multiplexing. In wavelength division multiplexing, the multiplexer (MUX, Encoder) and the demultiplexer (demux) one on top of the other matched color filter (or selective mirror). In the polarization process Polfilter (for Mux and Demux) are used. When the Time division multiplexing methods send the light sources of a group synchronous light pulse while the cameras of this directional group perform the exposure process (eg using an LCD shutter for Mux and demux).

in the In the simplest case, a light source group consists of only one light source, and / or the associated Kameragruppe also only off a camera.

1 schematically shows a location with two light sources and two cameras.

The Invention will now be described in detail.

A Embodiment (a type of color or wavelength multiplexing) for preferably technical camera systems (eg production monitoring) for example, different (not or little overlapping) Color filter in front of the light sources and matching color filter before The cameras use each of the unwanted light sources filter out. The number of filters or camera directions is not limited to three (RGB), but can be arbitrary be (also infrared or UV possible). It can also used filters with several pass colors at the same time become. Of course, optional monochromatic (or spectrally restricted, such as fluorescent lamps) Light sources used as an alternative to (or also with) the color filters become. The color filter may optionally also have a time-dependent (eg, periodic) transmission spectrum.

A Another embodiment (polarization method) is in the use of polarized light. In addition (in each case parallel) polarizers (also polar filters) in front of the light sources of the placed a group and (matching, so parallel to the light source polarizers) Analyzers in front of the group of associated cameras. These Embodiment is typically on two directional groups limited, but there are also three of these groups possible if a weakening in half (0.5 = cos (60 °)) is sufficient. Even if part of the Polarization is lost in reflections or scatters, so prevents the polarization method direct blinding by backlighting or the visibility of the unwanted light sources. Naturally Optionally, light sources that are self-polarized may also be used Generate light (eg laser). The analyzer (a additional polarizing filter in front of the camera) can optionally also by a rotating polarizer are formed. This could by means of a camera the respective fields (or other picture parts) be recorded with changing illumination.

Another embodiment (which is the preferred variant) uses a time division multiplex method. For this purpose, pulsed or self-shined light sources and (in groups) temporally offset (serial) recording times are used. The light of a source group should be emitted simultaneously with the actual recording time of the single image (eg during shutter opening). The duration of the light plays rather a subordinate role (300 km / ms), however, the quality of the sharpness of the pulse of the light source already rather. Light bulbs, for example, are (with direct use), due to their afterglow, only conditionally for high pulse rates. However, the light of each temporal (quasi-continuous) source may be chopped off by a source shutter (eg, LCD shutter). Optionally, the shutter can also be applied to illumination reflectors (or a mirror with a time-dependent reflectance is conceivable).

In front every light source (with appropriate size also at some distance from it) can be a controllable shutter (eg switchable glazing). It is possible, partially (or completely) absorbing the source light (Absorber) or diffuser (diffuser), as in both cases less light blasted in the original beam direction becomes. Alternatively (but also at the same time for shutters) can the light sources (except bulbs) optional as well be operated pulsed itself. Often decides primary the average power (thermal aspects) over the maximum brightness of light sources. For example LEDs can be pulsed up to the high megahertz range become. The usually annoying flicker (eg 100 Hz) of fluorescent tubes (or other gas discharge lamps) could be specifically exploited to pulsed light too generate, with the flicker (the peaks) in sync with the camera shutter or to the actual exposure process should take place. It may optionally be necessary in the short breaks a small residual current maintain, so z. B. not for every light pulse must be re-ignited. The luminosity most of the light sources is (partly with a slight delay) current-dependent (eg approximately linear).

By the optional modification of ECG (electronic ballast) Accordingly, periodic light pulses could be generated. A stroboscope (strobo) also generates light pulses. They are also stroboscopic Chains (to increase the power) conceivable, the serial send the individual light pulses.

Naturally should all light sources of a group (in the time-division multiplexing) radiate (largely) synchronously. The eye is in comparison to the light sources or cameras very sluggish and therefore takes a high-frequency Flicker barely true.

These Time control of the method can be over (eg at start of shooting) synchronized watches are made with sufficient accuracy, or via a common trigger pulse (eg by radio, Data cables, or power cables; The mains frequency can also be used as a time signal serve).

All Light sources of a group emit synchronous light pulses (setpoint). These pulses should be the bulk of their intensity during the respective recording of the individual images of the associated Have cameras.

The Clocks of different groups have a predefined offset (a groupwise constant offset), or the controlled event (eg shutter opening, read-out process, light pulse transmission) takes place delayed by this offset.

Various Groups (cameras with associated light sources) are running asynchronous, but with the same period. They are theoretical Any number of groups (during a scene) possible, provided the light pulses are sufficiently sharp and the lighting or Recording a single image (or image section) sufficiently fast.

On The timed light pulses should match the inclusion of the appropriate one Single image (or image area) done. The camera clock (for the shutter or readout process) runs naturally synchronous to the clock of the associated light sources.

There Cameras often have a shutter anyway, just have to whose opening time are controlled.

alternative the camera shutter can also be used with electronically readable (CMOS, CCD, Ikonoskop, Vidiconoder or similar) image sensors reading out or exposing the individual image (or the image area, z. B. a line) time window controlled. To do this possibly adapted to the conventional readout methods become. It could optionally also useless intermediate images deliberately discarded (skipped frame) and / or optional additional higher frame rates are recorded.

optional should quality over a digital display be judged the desired lighting condition.

It is not a strict separation of the different temporal group light pulses necessary, they should only be largely temporary disjoint (that is, having little overlap).

One Another advantage of the invention is the possibility of energy-saving Illuminate as the light energy only during the actual Single-frame lighting must be available, (but z. Not if the shutter is currently locked). This can reduce the average power consumption the light sources are lowered.

One Another advantage is the possibility of the procedure low Retrofit. For example, only the Ballasts of the light sources are exchanged, LCD shutter In front of the light sources attached, the shutter of the camera with the respective Clock are synchronized and / or the electr. Readout of the Picture (or area).

at Light sources with high heat radiation can optionally be Heat protection glass (between radiation source and shutter or color filter or polarizer) may be necessary.

All above method (embodiments) can at the same time, combined with each other.

The claims describe:
A method of simultaneously filming a multi-camera filmed object from multiple directions wherein a multiplexer encodes the light of the light sources via a multiplexing process and a demultiplexer on the cameras uses the selection of the appropriate amount of light for exposure.

One Method of the multiplex method, the polarization of light relates to the color of the light, or a time division method over Is light pulses.

A Arrangement for simultaneous film recording of a filmed object characterized by multiple cameras and multiple light sources a multiplexer that receives the light from the sources via a multiplexing process coded and a demultiplexer to select the appropriate proportion of light for the exposure in the respective camera.

A Device in which the multiplexing process the polarization of Light is concerned, the color of the light, or is a time division multiplex method.

A Device in which the light pulses of the time-division multiplex method using a shutter, preferably an LCD shutter, or pulsed light sources be generated.

A Apparatus in which a time-division multiplexing method is used, with a demultiplexer of a device to time coordinated reading of the camera sensor has, or with a camera shutter, preferably an LCD shutter, for tuning the exposure time in sync with the associated light sources.

A Apparatus in which a time-division multiplexing method is used, in which the pulsed light sources, preferably gas discharge lamps, through a periodic time-dependent current flow are, and preferably with an input for a synchronization signal to synchronize the pulse time.

A Application of the invention to single-frame photography is possible.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited non-patent literature

• - http://www.movie-college.de/filmschule/filmgestaltung/anschlussfehler.htm [0002]
• - http://pwimmer.gmxhome.de/LoadFrames.html?/3D/3DVideoTechnique.html [0005]
• - "glaswelt" 7/2003, page 24, part III, 8/2003, page 22 [0012]

Claims (7)

A method for simultaneous film recording a filmed object with multiple cameras from multiple directions in which a multiplexer over the light of the light sources a multiplexing method, a demultiplexer on the cameras the selection of the appropriate proportion of light used for the exposure and the cameras with similar line of sight and their associated Lighting can be grouped into directional groups. The method of claim 1, wherein the multiplexing method: a) concerns the polarization of the light, b) the color of the light concerns, or c) a time division multiplex method is used and where different directional groups are asynchronous to each other Exposure, preferably in real-time recordings. An arrangement for simultaneously recording a film Filmed object marked with multiple cameras from multiple directions through a multiplexer of the light of the light sources over Multiplexing encodes a demultiplexer on the cameras of the the selection of the appropriate proportion of light used for the exposure and the cameras with similar viewing directions and their associated lighting grouped into directional groups. Apparatus according to claim 3, wherein the multiplexing method: a) concerns the polarization of the light, b) the color of the light concerns, or c) a time division multiplex method is used and where different directional groups are asynchronous to each other Exposure, preferably in real-time recordings. Device according to one of claims 3 or 4, in which the light pulses of the time-division multiplexing method by means of a shutter, preferably LCD shutter, or pulsed light sources are generated. Device according to one of claims 3 to 6, in which a time-division multiplexing method is applied, with a Demultiplexer of a device for timed Reading out the camera sensor, or with a camera shutter, preferably an LCD shutter to adjust the exposure time synchrony to the associated light sources. Device according to one of claims 3 to 5, in which a time division multiplex method is applied, in which the pulsed light sources, preferably gas discharge lamps or LEDs characterized by a periodic time-dependent current flow, and preferably with an input for a synchronization signal to synchronize the pulse time.