WO2003014826A1

WO2003014826A1 - Animation of image sequence

Info

Publication number: WO2003014826A1
Application number: PCT/DK2002/000510
Authority: WO
Inventors: Eskil MØHL; Anders Munck
Original assignee: Steinbauer Aps
Priority date: 2001-07-24
Filing date: 2002-07-24
Publication date: 2003-02-20

Abstract

The invention relates to methods and devices for animation based on a sequence of fixedly mounted, discrete images, whereby a viewer who moves in relation thereto will experience an animated image sequence, wherein compensation is made for the angles at which the viewer observes the image faces, whereby the proportions of the image are experienced as being approximately correct. Corresponding to the invention compensation is made for the image such that the part of the image face viewed with the smallest distance between viewer and image face have been downscaled in relation to the parts of the image that are viewed with a larger distance.

Description

Animation of image sequence

FIELD OF THE INVENTION

The invention relates to methods and devices pπmarily for animation based on a number of fixedly mounted discrete images, whereby a viewer moving in relation thereto experiences an animated image sequence.

BACKGROUND OF THE INVENTION

The background on which it is possible to create the impression of movement by observing a number of discrete individual images is the phi-effect (inertia of the eye) that makes use of the fact that, within certain limits, the eye/brain does not perceive a number of individual images as such, but rather the brain allows the images to "merge".

It is thus well known that when movies are shown, it is possible to obtain an animated effect by intermittently showing a sequence of non-identical, discrete images, which principle is also applied to cartoons, the only difference being that the individual image is a drawing. Conventional movie shows may take place by projecting in sequence transparent images onto a face, such as a cinema screen, or by creating the images directly on a screen as is the case eg on a TV screen.

However, it is also well known that fixed images may also bring about an animated effect, eg by quick "leafing" through a pad with sheets of paper that have, at their edges, a number of drawings that combine to bring about an animated image sequence. This method is typically used when sketches for cartoons are being made.

However, devices as such are also known, whereby it is possible by means of fixedly mounted, discrete images to obtain an animated effect. One example of this includes optical toys that have been known for more than 100 years, wherein, by means of a mechanical arrangement, it has been possible to impart the impression that images are animated. However, such toys have always be limited by their ability to be used only for short animated sequences and by their effect being conditioned by a specific distance and viewing angle. Most often the images are located on drums, rotating discs and the like, and the effect was achieved by means of openings that enabled display of the individual image for only a fraction of a second.

The desire to make it possible to animate images mechanically without being restricted to short animated sequences and without being dependent on a specific distance or viewing angle has been acknowledged for a number of years, and a number of devices for realising this object are available, in particular with a view to displaying animated sequences to an observer who moves past an arrangement of fixed images. Typically the observer is in or on a means of transportation, eg a train, a car or an escalator, and the images are typically arranged on a wall face, eg the wall of a tunnel or a number of billboards.

The prior art solutions are typically based on two different principles: (1) the stroboscope-principle, whereby images on an open face are illuminated in short bursts, and (2) the lamella-principle, whereby the images are arranged in such a fashion that the images can be viewed from a given position only. The stroboscope-solution is, as the name implies, based on a stroboscope lamp emitting, for the individual image, short bursts of light and displaying the image for a fraction of a second. A clear and well-displayed image results that animates like a television set, but the principle presupposes a relatively complex control and, likewise, the establishment and operation of the light sources are costly.

The lamella-principle relies on the image being visible only from one more or less acute angel, whereby the image is displayed only in a flash as you pass it by. This principle hardly requires any technical measures, it easy to maintain, but can be viewed only from specific angles and often yields a slightly blurred display. This principle is described in detail in WO 96/138/22.

In order to obtain a more clear image, the lamellae can be configured such that each individual image is "scanned" by the viewer, ie the individual image is constructed of partial image components on the eye's retina which are, due to the inertia of the eye/brain, perceived as one single image. This is described in Danish patent application No. PA 1998 01240 that discloses a device that shows specific sections of an image in accordance with the angle at which the image is viewed, whereby - upon movement relative to the face with ensuing continuous change of the angle - a complete image is displayed as a continuous sequence of vertical sections.

Since typically the viewer will not change his point of fixation, the image is detected by a "scanning", during which the continuously scanned area of the image moves across the retina. In case of quick movement relative to such image, the illusion will result that it has been stationary relative to the viewer. The effect of such arrangement does not depend of the position of the viewer relative to the image, due to the image being "drawn" in front of the viewer and not needing to be viewed close up. The movement relative to a sequence of individually drawn images, wherein each individual image thus seems to emerge and disappear again at the same place relative to the viewer will mean that a sequence of images is perceived as being animated.

To obtain the continuous image detection, an arrangement is used for each image, wherein a plate of an opaque material is mounted at a certain distance from the image, and wherein the plate comprises a vertical, relatively narrow opening for each of the individual images in the animated sequence. In order to be able to re-establish the image on the retina in the original format, it is necessary to downscale the image horizontally, or in other words to make it narrow. The parallax-difference by movement horizontally past the vertical slot thus results in the representation of the image being, to the viewer, re-established in the original format. In connection with the nomenclature used in the application, this scaling is referred to as the initial scaling. The application does not contain any specific description of the guidelines according to which this scaling is to be performed.

The animation will thus be accomplished by horizontal movement relative to a sequence of such images that are re-created on the viewer's retina, eg by the viewer being on a train that moves through a tunnel on the wall of which the images are arranged. Thereby the horizontal movement brings about both the reestablishment of the image and its animation.

The lamella principle described above is also described in US patent application GB-A-2230 101.

In order to ensure adequate animated effect, it is necessary to determine in advance a sufficiently large number of "frames", ie separate images, per second, typically between 12 and 24, where it applies to each individual image that it must appear sharp and sufficiently illuminated to ensure an acceptable contrast relative to the surroundings. Since the speed of movement of the viewer relative to the sequence of images is typically determined in advance, eg the speed of a train through a tunnel, the number of frames per second will be determined by the distance between the individual images, as is described in detail in WO 96/13822.

In order to further enable control of the image formation, PA 1998 01240 describes how the images can be scaled (compressed) horizontally, resulting in a sequence of "narrow" images.

BRIEF DESCRIPTION OF THE INVENTION

It is a typical feature of the above-cited prior art that the distortions of the images that will occur as a direct function of the geometric conditions during viewing of the images, including the angles at which the viewer views the images, or parts there of, through the slots, are not taken into consideration.

When, in the following, the terms "horizontal" and "vertical" are employed, they are intended to be merely illustrative and not to relate specifically to the particular situation in which a viewer moves in the ideally horizontal plane. More generally, the terms "horizontal" and "vertical" as used in this application are intended to designate just a first direction and a second direction perpendicular thereto, wherein the first direction is determined by the direction of movement of the viewer, ie in case the viewer moves "uphill" the term "horizontal" covers this situation, too. In the following the terms "viewer/view" and "observer/observe " are used synonymously, and likewise the viewer can be natural, eg a person, as well as non-natural, eg a camera.

The present invention is based on the findings that in order to create an animated image with approximately correct proportions when viewed through a narrow slot, it is necessary to compensate for the actual conditions in which the image is viewed, including the angles at which the viewer observes the image faces, the distance between the various elements (viewer, slot wall, image face), and the shape of the image faces as such. The term "correct proportions" is to be understood as establishment of an image with the "original" proportions contained in the starting material. By the term "approximately" is to be understood that a correct geometrical compensation is, in theory, only possible for one single point that can be moved relative to the image faces, eg one single viewer seated in a predetermined space in a train. It follows that an average position for a viewer must be determined, but that it will apply that to viewers located around this average position, the thus created image will be perceived as considerably more correct compared to the situation where no compensation for the geometrical conditions was made.

More specifically the above is obtained by compensation for one or more of the following conditions: the angle in the horizontal plane at which the images are viewed, the angle in the vertical plane at which the images are viewed, and the curvature of the image faces in the vertical plane. When, in the following, the terms "upscale/downscale" are used they are intended just to denote relative indications, which means that downscaling can be performed by upscaling other areas of the image face.

Corresponding to the first circumstance, compensation is made for the horizontal viewing angle by scaling of the image in the vertical direction as a function of a horizontal position, whereby the part of the image face that is viewed with the smallest distance between viewer and image face has be downscaled relative to the parts of the image that are viewed with a larger distance. Of course, this also applies to all intermediate distances and it follows that this is a continuous scaling of the height of the image in its longitudinal direction. This will entail eg that in a situation, where the viewer looks forwards the actual image will decrease in height towards the viewer in order to thereby appear as a trapeze-like figure with parallel, vertical edges, and therefore such image will be typical for this aspect of the invention.

Corresponding to the second circumstance, compensation is made for the vertical viewing angle by scaling the image in the horizontal direction as a function of a vertical position, whereby the part of the image face that is viewed with the smallest distance between viewer and image face is downscaled relative to the parts of the image that are viewed with a larger distance. This also applies to all the intermediate distances, and it follows that this is a continuous scaling of the width of the image in its longitudinal direction. This will entail eg that in a situation, where the viewer looks upwards the actual image will decrease in width away from the viewer in order to thereby appear as a trapeze-like figure with parallel, horizontal edges, and therefore such image will be typical for this aspect of the invention.

Corresponding to the third circumstance, compensation is made for a curved image face by scaling the image in the horizontal direction as a function of a vertical position, whereby the part of the image face that is viewed with a smaller distance between viewer and image face than the part of the image face that is viewed with a larger distance is downscaled relative to the parts of the image that are viewed with the larger distance. This will mean eg that in a situation where the viewer looks into a curved (concave) tunnel wall, the image will decrease in width towards the top and bottom of the tunnel.

The above-described scalings are additive, whereby - according to choice - it is possible to compensate for one or more of the three parameters. This would result eg in the actual image appearing as a figure with pairs of non- parallel sides that may be straight or curved, and it follows that such image will be typical for this aspect of the invention.

It follows from the above that, in the widest aspect of the invention, it is simply its object to compensate for the described circumstances to such extent that the viewed image will, to a given viewer, be perceived more correctly than in case no compensation was made. As will appear, the described scaling will require a relatively comprehensive processing of images, but to eg a digitally represented image, this could be obtained with the standard functions of a conventional computer-based image-processing program, ie the individual image can be "drawn" or "withdrawn" as needed.

The exact degree of scaling will, as described above, be subject to a choice made by the skilled person taking his starting point in the relevant situation, but since the described overall correlation between scaling and the resulting effect is equivocal, they will merely be experiments of routine for determining the scaling necessary for the various parameters.

According to a more narrow aspect, the invention relates to a number of mathematical formulas that determine, for a set of given values, a composite transfer function between the desired, perceived image and the actually perceived image. Albeit these formulas will lead to the "correct" solution it is important to point out that, as mentioned above, it is a theoretical solution and that the determination of the parameters of the formulas will highly influence the impression imparted to a large number of viewers in various positions, eg passengers in a train compartment. These formulas also enable determination of the aforementioned initial scaling.

When it is stated above that the invention relates to animation, this concept also covers the particular case where a still image is animated, ie all images are identical.

Corresponding to a further aspect of the invention, it relates to a system for showing an animated sequence of images, comprising a number of mirrors, wherein the system for showing images comprises a first face comprising at least one slot-shaped opening, wherein - for each opening - there is arranged a first mirror and a second mirror opposite the opening with their respective planes oriented in parallel with the slot-shaped opening, and wherein the two mirrors are oriented towards a first and a second area, respectively, to each their side of the slot-shaped opening, whereby the first area can be viewed through the slot via the first mirror and the second area could be viewed through the slot via the second mirror.

DESCRIPTION OF THE DRAWINGS

In the following, the invention will be described with reference to the drawing, wherein

Figure 1 shows the front of a mounting box with vertical, narrow openings;

Figure 2 shows an opened box;

Figure 3 shows the explanatory circumstances for the experienced image;

Figure 4 an explanatory representation for scaling in the horizontal direction; Figure 5 shows an explanatory representation for scaling in the vertical direction;

Figure 6 shows a representation corresponding to that of Figure 4, but wherein mirrors are used;

Figure 7 shows a representation corresponding to that of Figure 5, but wherein mirrors are used; and

Figure 8 shows an embodiment with a mounting box, wherein two mirrors are arranged for each slot opening.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

As described initially, this invention relates primarily to the creation of an animated sequence when a sequence of images is viewed through a narrow slot belonging to each image, while the viewer moves along the sequence of images.

Figures 1 and 2 show a simple mounting box for use to this end. The box comprises a front plate 1 with a number of vertical, slot-shaped openings 2, typically one per image, arranged in front of a back wall of images whose width will normally be downscaled. The front may be tilted upwards or outwards by means of a hinge at the top or on the side of the box, whereby the images there behind can be changed. Each box may optionally consist of several lids, depending on their weight. A total arrangement inside eg a tunnel would normally comprise a large number of boxes. The boxes are configured and dimensioned in accordance with the given circumstances, but typically an arrangement could consist of a sequence of boxes having a length of 5-10 meters with slots that have a height of about 1 meter and a depth of about 4-8 cm. Each box has a number of light pipes 3 at the top and at the bottom throughout the entire length of the box and which illuminate the images 4 on the back face of the box. Figure 2 shows an opened box with a back wall to the left and front with light pipes 4 to the right. As mentioned initially the illumination is selected in accordance with the prevailing conditions, for one thing depending on the surrounding conditions of light, but also the time during which the individual image is observed by the passer-by to ensure that the images "remains" on the retina. Depending on the geometrical conditions, separating walls 6 can be mounted between the individual images, whereby it is ensured that a viewer sees only one image at a time.

As described initially there are four types of scaling that should be considered in connection with the realisation of the invention.

(1 ) Initial scaling: Here the image is down-scaled horizontally to achieve the "movie" effect without the image being experienced as too wide and impossible to see. This scaling depends primarily on the distance between the viewer, the slot and the image face, respectively, and in most cases it is necessary for the animation to be seen in the intended, "original" format.

(2) Vertical compensation: Here the image is scaled if the viewer is located above or underneath the image on the wall in order to compensate for the vertical displacement of the viewer. This yields an image that has, following the compensation, either a narrower dimension at the top or at the bottom.

(3) Horizontal compensation: Here the image is scaled if the viewer looks inwards at the wall at an angle in the horizontal plane. Thus, in this case compensation is made for the viewer looking slightly forwards or backwards relative to the direction of advancement. This yields an image that has, following compensation, a slightly smaller dimension at the right-hand side or at the left-hand side.

(4) Compensation for curved wall: Here compensation is made to enable an image hung on a curved wall to be viewed in its original format. In case of a concave wall, this means that the compensated image will be the widest at the centre in the vertical axis. In case of a convex wall this means that the compensated image will be the narrowest at the centre corresponding to the vertical axis.

It applies to these four scalings: (1 ) this is the scaling described in principle in PA 1998 01240 and will usually be necessary. Concerning (2) and (3), this is an optional compensation in the mentioned cases that makes the image representation appear as if it is perpendicular to the direction of viewing of the viewer. In other words, it represents the image face as if it points directly towards an observer rather than imparting the impression that the image is viewed at an angle. Concerning (4), this is a compensation for the fact that the format of the image need not be changed if it were to be hung on either a concave or a convex surface.

Figure 3 shows the explanatory conditions that it is desired to realise. A viewer with an eye point 10 sees ahead of him at an angle β relative to the front of the box 12, behind which images (not shown) are arranged on a face 13. As described above, the front is provided with a number of slots (not shown). Reference numeral 11 designates the image that it is desired to realise, ie a "virtual" image that is experienced as being located perpendicular to the viewing direction and with correct geometrical proportions. The angle β shown in the figure may both represent an angle in the horizontal and the vertical planes, as will be elaborated below in connection with the description of a theoretical solution to the scaling with regard to the various parameters.

The following relates to the conditions that are given in order to enable establishment of animated images for a bypassing viewer when images are fixedly mounted on a wall behind another wall provided with slots. In particular the scaling of the fixed image will be discussed in relation to the animated (realised) image. Below, reference is made to the animated image field, which is the image viewed/experienced by the viewer, as well as to the fixed image, which is the image mounted on the wall.

The scaling of the fixed image can be divided into independent scalings in the horizontal and vertical directions. It applies to the horizontal scaling: (refer to Figure 4).

Horizontal scaling

The width of the animated image field Ax [m]

The width of the fixed image Bx [m]

Perpendicular distance between viewer and animated image field Cx [m]

Perpendicular distance between viewer and slot wall Dx [m]

Perpendicular distance between slot wall and fixed image Ex [m]

Position of front edge of image relative to slot Box (F 1 )

Angle between normal to animated image field and slot wall βx

(horizontal viewing angle)

Position on animated image field ax [m]

Position on fixed image bx [m] (F 2)

In order to make the animated image appear with correct proportions, it shall apply that the position of the image section seen in the animated image corresponds to the corresponding image position seen by the viewer through the slot.

b = f(a_x, A_x, Cx, E_x, βx)

On the basis of trigonometrical deliberations, the correlation between bx and ax can be deduced. The correlation is shown in F 1 and F 2, see appendix that shows the formulas F1 -F6.

Vertical scaling

The nomenclature refers to Figure 5.

The height of the animated image field Ay [m]

The height in the vertical plane of the fixed image By [m]

The height in the sideways plane of the fixed image Hz [m]

Perpendicular distance between viewer and animated lower edge Cy [m]

Perpendicular distance between viewer and fixed wall Dy [m]

Vertical distance from eye point to lowermost edge on fixed image

Hoy [m] (F 3)

Angle between horizontal from eye point to lowermost edge of image field αy (Vertical viewing angle)

Angle between image field and the horizontal plane βy

Position on animated image field ay [m]

Vertical position on fixed image hy [m]

Sideways position on fixed image sz [m]

Unfolded height of fixed image h [m]

sz, which is an expression of the curvature of the tunnel wall, can be expressed as a function of by (F 4).

The vertical scaling of the image is independent of the position of the slot wall relative to the location of the fixed image and the height and width of the slots. However, the height of the slots should be sufficient to enable the viewer to see the entire height of the image.

Parameter dependency While horizontal and vertical scalings are independent, it applies that some of the parameters depend on each other. In general it applies that

Ax = f 1 (hy) Cx = f2 (hy) βx = f3 (ax) Cy = f4 (ax) βy = F5 (AX)

It is presupposed that the parameters that describe the location and orientation of the tunnel wall and the slot wall are constant for each individual fixed image.

Width of the slots

In order for the animated image to be sharp, the slot width must be so small that at any time the viewer will be able to see only a small vertical section of the fixed image. This can be expressed by the relation between the width of the fixed image and the width of the slot not being allowed to exceed a given ratio. This means that

wherein B_s is the horizontal slot width. In the figures the slot is illustrated as a line "without width".

Slot wall with mirrors

In an arrangement, wherein the tunnel wall is provided with mirrors and the fixed image is located on the back side of the slot wall, it applies to horizontal scaling that F.1 and F.2 are valid when the distance between slot wall and the fixed image Ex is replaced by to times the distance between slot wall and the tunnel wall, where the mirrors are located. See Figure 6.

For the vertical scaling with mirror arrangement formulas F1 , F2, F3 and F4 apply when Dy is inserted as

Dy = Ey +2 G (F.7)

As will appear from the above the formulas thus produced are general and take into account all possible (ie desirable or undesirable) parameters.

The formulas are intended for use in the following manner. First the basic geometrical relations are determined, ie the angles of the viewing direction in the horizontal and vertical planes relative to the slot wall, and the distances between the eye point of the viewer and the slot wall, and between the slot wall and the image faces (the tunnel wall), respectively. If the viewer looks perpendicular onto the image faces the angles βx and βy will be 90° and this compensation will then be annulled, which fact has been taken into consideration in the general formulas.

Now the parameters of the "virtual" image are determined, ie its dimensions and the desired distance from the eye point. The virtual image should normally correspond to an original image, ie an image created by a graphic image reproducer or a draftsman, while retaining its properties.

When thus all of the above parameters have been determined it is possible for each "virtual" point ax, ay to determine an image point bx, by corresponding to a point on the image arranged on the tunnel wall. If the image face is curved it is possible to compensate therefor as outlined in Figure 5. These calculations are repeated for each one of the images of the image sequence. It also follows that the images need not be scaled in a similar manner, but that compensation can be made for varying distances and curvatures. In the above, the images are described as being located in correspondence with the back wall of the display box, ie corresponding to the tunnel wall, but it may also be possible, by means of mirrors located on the back wall, to view images arranged on the inner sides of the slot wall, which will - in accordance with the disclosures of Figures 4 and 5 - involve mounting of the images as shown in Figures 6 and 7, respectively. The use of mirrors makes it possible to reduce the depth of the mounting boxes.

Figure 8 shows an embodiment with a mounting box in which there is, for each slot opening, arranged two mirrors whereby a viewer who looks "forwards" through the slot via a first mirror sees a first image arranged on the inner side of the mirror plate, and a viewer who looks "backwards" through the slot via a second mirror sees another image arranged on the inner side of the slot plate, but to the other side of the slot. This arrangement makes it possible for two viewers to see each their animated sequence. The latter, however, would also be possible without use of mirrors, eg by alternatingly arranging images that can be viewed only from a given direction, eg "forwards" or "backwards" in relation to the direction of movement.

As was emphasized initially, the above-described theoretical solution is only "correct" for one single eye point, which will, of course, not apply to the individual viewer who will almost always be outside this point. The choice of the "optimal" eye point is therefore an individual choice adapted to the given situation in order to thereby achieve the best average effect for a group of viewers.

As was also emphasized initially the described scaling corresponding to the invention can also be carried out without use of the above-given calculation models, but may accomplished exclusively with starting point in the described general correlation between the various types of scaling and the thereby ensuing unequivocal effect, and therefore the experiments performed will exclusively be routine experiments for determining the necessary scaling of the various parameters.

Appendix

(F.l)

(F.2)

H_oγ = D_γ ^■ tan(or_r ) (F.3)

y - (C_r ^■ sin(α_r )+a_r ■ sin(?_r ))• Dy-f( y) - D_γ ■ tan(α_r ) (F.5)

C_y ^■ cos(a_r)- _γ ^■ cos(?₇ )

Claims

C l a i m s

1. A method of scaling an image face as compensation for the conditions in which a viewer views the image, comprising at least one of the following steps:

- to compensate for a viewing angle in the horizontal plane between the viewer and the image face by scaling the image face in the vertical direction as a function of a horizontal position, whereby the image face, corresponding to the vertical direction, is downscaled in a direction from the part of the image face that is viewed with the largest distance between viewer and image face and the part of the image that is viewed with the smallest distance;

- to compensate for a viewing angle in the vertical plane between the viewer and the image face by scaling the image in the horizontal direction as a function of a vertical position, whereby the image face, corresponding to the horizontal direction, is downscaled in the direction from the part of the image face that is viewed with the largest distance between viewer and image face and the part of the image that is viewed with the smallest distance; and - to compensate for a curvature of the image face in the vertical plane by scaling the image in the horizontal direction as a function of a vertical position, whereby the part of the image that is viewed with a smaller distance between viewer and image face than the part of the image face that is viewed with a larger distance is downscaled relative to the parts of the image that are viewed with the larger distance.

2. A method according to claim 1 , further comprising the step:

- to mount one or more images behind a sheet covering, wherein the covering for each image comprises a slot-shaped opening which is narrow compared to the image.

3. A method according to claim 2, wherein a number of images are mounted in sequence in the horizontal direction behind vertically oriented openings, and wherein the slots are configured such that a viewer will, when passing by the sequence of images in the horizontal direction, be able to observe the images individually in the given sequence, preferably such that the images are different in order to thereby create an animated effect.

4. A method of establishing a system for creating an animated effect to a viewer who moves in relation to the system, comprising:

- to produce a sequence of images, wherein the images are preferably initially downscaled in one single dimension; - to mount the images at a distance from each other on a face, where the face may comprise a curvature;

- to shield each of the images by means of an essentially opaque shielding , wherein the shielding of each of the images comprises a slot-shaped opening which is narrow compared to the width of the image, and wherein the openings are preferably oriented perpendicular to the direction of scaling of the images;

- to determine a viewing direction for a viewer who moves in a direction along with the images;

- to determine a viewing angle in the horizontal plane between the viewer and the individual image face;

- to determine a viewing angle in the vertical plane between the viewer and the individual image face;

- to determine a distance from the viewer and a dimension of the images the viewer is to experience when viewing the images through the openings;

- to compensate for one or more of the parameters: viewing angle in the horizontal plane, viewing angle in the vertical plane, and for a curvature of the image face as featured in claim 1.

5. A method according to any one of claims 1-4, wherein the compensation has been carried out with one or more of the formulas designated F1-F7 and the variables contained therein.

6. A method of scaling an image in one single dimension by use of the formula designated F2.

7. A system of displaying images, comprising: - a first face comprising at least one slot-shaped opening;

- wherein, for each opening, a first mirror and a second mirror opposite the opening are mounted with each their respective planes oriented in parallel with the slot-shaped opening;

- and wherein the two mirrors are oriented towards a first and a second area, respectively, to each their side of the slot-shaped opening, whereby the first area may be viewed through the slot via the first mirror, and the second area may be viewed through the slot via the second mirror.

8. A system according to claim 7, further comprising a second face arranged essentially in parallel with the first face and on which the mirrors are mounted.

9. A system of creating an animated effect to a viewer who moves in an essentially horizontal direction in relation to the system, comprising:

- a sequence of images mounted at a distance from each other on a face, where the images are shielded by means of an essentially opaque sheet, wherein the shielding comprises, for each of the images, an essentially vertically oriented, slot-shaped opening that is narrow relative to the width of the image, wherein the images comprise two pairs of opposite sides, and wherein the images have been scaled such that the sides for at least the one pair are non- parallel.

10. A system of creating an animated effect in accordance with claim 9, wherein the images have initially been downscaled in one single dimension, preferably in the horizontal direction.