GB2054901A

GB2054901A - Three Dimensional Images

Info

Publication number: GB2054901A
Application number: GB8015331A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-05-11
Filing date: 1980-05-09
Publication date: 1981-02-18

Abstract

According to this invention, the means for producing a three- dimensional reproduction of an object or scene, as viewed from around a 360 DEG arc, comprises a series of photographs 2 taken from around a circle which are reproduced anamorphically and mounted within a cylindroid 6 composed of positive- focus cylindrical lenses, with an image behind each lens to produce an isomorphic virtual image, at a pre- calculated conjugate-focus, which superimposes in register with the virtual-images produced by adjacent lenses. The object so represented is observed through the group of lenses nearest the viewer, and appears to remain stationary when viewed from around the cylindroid through a succession of groups of lenses, but varies according to the angle of view therein represented. <IMAGE>

Description

SPECIFICATION Means for Producing Three-Dimensional Representations of Views Through a 3600Arc This invention relates to the representation of a panoramic scene and of the perifery of an object wherein three-dimensional views through a 3600 Arc are exhibited, with parallax, within a cylindroid.

Known means for producing a periferogram either require a continuous angle-of-view to be recorded and fail to include parallactic information by depicting the object's perifery as viewed perpendicularly at each point only, or require laser-light holographic techniques wherein colour rendition is a problem.

Now, the object of this invention is to enable a stereoscopic photographic reproduction, in colour, of an object viewable from all sides, or of a scenic panorama viewable through a 3600 arc, to be made, and for the three-dimensional reproduction to be viewed by the naked eye, i.e. without the necessity of employing special glasses or equivalent analysing apparatus, and without the necessity of employing holographic techniques.

According to the said invention the three-dimensional representation is produced by a method which includes reproducing, with a camera and with an anamorphotic lens, a series of views of the object or scene taken towards the centre of a circle from a plurality of equally-spaced positions around its circumference, in order to produce a measurable degree of anamorphism in the image representing each angular view. The said images are fixed by any suitable mounting, in a one-to-one relationship, behind a similar plurality of positive-focus cylindrical lenses which are abutted by their vertical, adjacent, straight edges to comprise a hollow cylindroid within which the images are mounted.The particular principal-focal-lengths of the said lenses and the particular distance behind a lens at which an anamorphic image is mounted are pre-calculated, in each case, as hereinafter described, to produce horizontal enlargement of each image, equal in degree to its horizontal width compression, in its virtual-image which is superimposed on the other virtual-images produced in a similar manner by the lenses and images adjacent to it, so that, at their common conjugate focal-plane, the overlapping edges of adjacent virtual-images mutually superimpose, substantially in pictorial register.

Thus the object so represented is observable through the group of adjacent lenses nearest the viewer, and appears to remain stationary when viewed from around the cylindroid through a succession of groups of lenses, but varies according to the angles of view therein represented. Objects at various distances, whose representations in superimposed virtual-images fail to register at the preselected conjugate-focus, exhibit relative parqllactic displacement when observed through various groups of lenses which exhibit various angular views.

The invention further consists in apparatus for producing and exhibiting a stereoscopic reproduction of an object or scene with a 3600 viewing angle, the said apparatus including (1) A cylindroid composed of, or containing, a plurality of positive-focus cylindrical lenses of any type including those with convex surfaces, or Fresnel lenses, whose principal-focal-lengths are designed to be appropriate to the series of anamorphic images to be employed therewith, and (2) a similar plurality of images which represent a series of photographed views taken towards the centre of a circle from a similar plurality of equally-spaced positions on its circumference, the said images being reproduced anamorphically, to a size which enables them to be mounted within the cylindroid with each image accurately located at a pre-calculated distance behind a lens.

The cylindroid may be machined or moulded in glass or plastic or may be assembled by fixing a plurality of lenses, or lens-elements, edge-to-edge to produce the cylindroid.

The series of anamorphic images may be produced from a plurality of photographs taken by a kinematographic or "still" camera which may, or may not, be equipped with an anamorphotic lens. The camera may be physically moved around the circle, or may remain stationary while the object to be photographed is rotated by a rotatable mounting in order to photograph the series of angular views.

The series of images so obtained may be reproduced, with the dimensions and degree of anamorphism necessary with a given cylindroid to produce the three-dimensional representation, by photographic enlargement with a projector which may utilise a variable-power anamorphotic projecting lens of standard or known construction.

Various sizes of representation may be provided by various sizes of cylindroid in which all dimensions of the cylindroid and of the images are scaled in proportion to the corresponding dimension of a notional cylindroid, whose lenses are taken to be equal in width to the equally spaced camera positions, and whose circumference is taken to be equal to, and superimposed on, the circle employed in photographing the series of views.In the notional cylindroid, the principal-focal-length and conjugate foci of each notional cylindrical lens, necessary to produce magnification equal in degree to the anamorphism produced and measured in the images prepared for mounting with a cylindroid, is calculated by inserting the value of the measured camera-to-object distance and the degree of anamorphism in the following standard lens equations:- V Equation No. 1 F=----- F M-1 and F(M-1) Equation No. 2 u=- wherein, M F=principal-focal-length of a cylindrical lens, V=radial distance, or average radial distance, from camera to object, M=magnification by lens of each image's width, being the inverse of the image's anamorphism, u=the conjugate focal-length between a lens and an image.

Thus in each size of cylindroid its radius, the lenses' and images' widths, the necessity conjugate focal-lengths and the lenses' principal-focal-lengths, are all scaled, in the same ratio, in relation to the dimensions of the notional cylindroid.

The mounting for the images is provided by either one of two general types of structure, in one of which the images' surfaces are located in contact with the inner surface of the cylindroid which is shaped to locate and support each image on a len's conjugate focal plane. In this type of mounting the lens-to-image distance denoted by "u" in Equation No. 2, above, is provided by the appropriately designed thickness of the cylindroid's wall. In the other type of mounting the images are supported at the distance denoted by "u" in the above.

Equation No. 2, by, for example, a cylindric structure to which the images are attached and which is located concentric within the cylindroid of lenses by means of, for example, flanges or stays which connect the images' supporting structure of the cylindroid at their ends.

Images visible near the edges of the cylindroid do not contribute to the field of view as seen from each viewpoint and may be masked by opaque or translucent strips inserted between the cylindroid and the images' surface in line with the abutting edges of the lenses and the edges of adjacent images.

Masking of images near the edges of a cylindroid which employs lenses operating at an effective "F number" of one, or thereabouts, may be adequately provided by the lenses' mutual screening, and by light externally reflected from the cylindroid's edges, as viewed.

The viewing angle of each lens may be increased, for lenses whose conjugate focus is a curved field, by providing curvature of each images' surface about a radius on the lens's optical centre. In this arrangement the sine of 21 the angle of view of a lens one lens's width 2ximage to optical centre and the width of the field of view exhibited by the cylindroid from each viewpoint =(sine 5 angle of view of lens)x(diameter of cylindroid).

In order that the present invention may be clearly understood and readily carried into effect, constructional embodiments thereof are hereinafter more fully described with reference to the accompanying drawings, wherein Figure 1 is a plan view of the disposition, around a circle, of viewpoints from which a series of images is produced with a camera, Figure 2 is a cylindroid whose inner surface is shaped to provide curvature of each image's surface mounted in contact therewith, Figure 3 is an image-supporting sheet which is shaped in preparation for its insertion into a cylindroid, and Figure 4 is a partly exploded view of a cylindroid with an image-supporting sheet mounted concentrically remote from the cylindroid's inner surface.

Referring now to the said drawings, and in particular to Figure 1 thereof, the equally-spaced viewpoints 1 are marked on the circumference of a circle 2 which may be drawn on a fixed surface, and around which a camera 3 is serially moved to each viewpoint, in order to produce a series of photographs with the camera aligned towards the circle's centre 4. Alternatively, viewpoints may be marked on a rotatably mounted table, which supports the object, and which is turned to bring each viewpoint in line with a fixed camera 3. The succesive exposures by the camera can be timed to coincide with its alignment with viewpoints marked on a table whose rotation is produced by a constant speed motor.

In each of the foregoing arrangements a series of photographs produced by, for example, an isomorphotic lens in a still or ciné camera 3 are projected anamorphotically, in succession, onto a sheet of film to produce photographically a series of adjacent anamorphic images as a master film. The master film is magnified by isomorphic projection to produce photographically an image sheet on a paper or plastic support for mounting in a cylindroid, on which sheet the distance between the mid lines of adjacent anamorphic images is equal to the width, including any curvature, of an image mount on its cylindroid. The master film may be produced directly in a camera 3, equipped with an anamorphotic lens, in which the film is advanced, between each exposure, by one frame whose width is made equal to each anamorphic image's width in the camera.

In order to calculate the principal-focal-length for a cylindroid's lenses, and its radius, to produce a three-dimensional reproduction from a given master film, the camera-to-object distance, and the degree of anamorphism of the images on the master film, may be measured or computed and employed in equations Nos. 1 and 2 to thereby compute the principal-focal-lengths of the cylindroid's lenses, and the lens-to-image distance which would be necessary to produce the three-dimensional reproduction in a notional cylindroid, whose radius was the same as that of the circle employed with the camera. The dimensions of a cylindroid of any required size to be used with the same series of images may be calculated by scaling the dimensions of the notional cylindroid.

Conversely, to produce a three-dimensional reproduction of any object in a given cylindroid, the camera-to-object distance may be adjusted to include the whole object in the camera lens's field. The measured distance from the camera lens to the centre of the object is then taken as the radius of the circle on which equally-spaced positions for the camera's series of photographs, one for each cylindroid's lens, are marked. The series of photographs is taken and developed. The scale relationship between the radius of the circle and that of the given cylindroid is ascertained.The required virtualimages' conjugate focal distance, which is calculated from the camera-to-object distance by using this ascertained scale factor, is substituted for "V" and the known principal-focal-length of the given cylindroid's lenses is substituted for "F", in equation No. 1 in order to calculate the required magnification "M". The inverse of the value found for "M" is the degree of anamorphism to be produced in each of the photographs, which are projected through a variable-power anamorphotic lens to produce the series of adjacent images on the master film.The values for "F" and "M" are substituted in equation No. 2 to find "u", and this lens-to-image distance "u" is arithmetically deducted from the cylindroid's radius in order to determine the images' radius when properly located in the cylindroid, and hence the length of the circumference on which the images should be located by their mounting. This length, in this example, is the sum of the widths of the adjacent images, which are photographically reproduced to this size by isomorphic projection of the master film.

Referring again to figure 1, the angular field-of-view 5 of the camera 3 covers the same proportion of the circle's area 2 as the field of view seen in the completed device when viewed from any side, and objects located in the circular area 6 remain in the field-of-view seen throughout the 360" viewing arc.

Referring now to Figure 2, a cylindroid 1, which is made as a moulding of glass or plastic, is provided with abutted cylindrical convex lenses 2 whose surface curvature is a cylindric in order to reduce spherical aberration and to minimise internal reflections near each lens's edges.

The convex curvature of each image-mounting surface 3 is made the same as each lens's field curvature which may be determined for a sample lens by, for example, a ray-track apparatus employing a light beam the width of a lens to plot the curve which minimises the lens's wide-angle distortion.

The thickness of the cylindroid's wall, 4 measured from the lens's surface to the image mounting surface, comprises the distance denoted by "u" in lens equation number 2, plus the radius of curvature of the lens.

Referring now to Figure 3, the sheet of paper, film or plastic 1 onto which the adjacent anamorphic images 2 are printed, with each image equal in width to an image-mount, including curvature 3, is creased 4 along the edges of the images and bent to produce curvature 5 across each image's width. The creased images'-supporting sheet is inserted into the cylindroid 6 and aligned in contact with the curved image-mounting surfaces 3, to which it may be glued.

The images'-supporting sheet is made of, or supplied with, a light diffusing backing which is translucent if the cylindroid is to be illuminated from within.

Referring now to Figure 4, a cylindroid's lenses 1 are bi-convex and located concentric with a sheet of adjacent anamorphic images 2, which is creased 3 along the images' edges and bent to provide concave curvature 4 of each image's surface, by means of two similar flanges 5 which are fitted in contact with the inner surface 6 of the cylindroid 7 at its two ends 8.Each flange 5 is provided with lens-shaped excissions 9 which align its outer rim with the lenses, 1 and, at the flange's concentric inner rim further excissions 10 are provided whose shape is the same as a lens's fieldcurvature in order to support the images' surfaces 2 thereon, such that the abutting edges of adjacent lenses 11 and of adjacent images 1 2 are located by the flange on one of its radii and the separation 13 between each lens's optical centre and image's surface, denoted hereinbefore by "u" in lens equation 2, is provided by the annular width of the flange and the lenses in contact therewith.

Slots 14 are perforated in the flanges 5 in line with the edges of the lenses 9 and image-locating excissions, 10 and are arranged concentrically to provide mountings for the tabs 1 5 provided at the two ends of each opaque strip 1 6 of thin plastic. Each strip 1 6 is located and supported by the abutting edges 1 7 of the lenses' convex surfaces. The opaque strips 1 6 mask from view images at the edges of the cylindroid, as viewed, which do not contribute to the field of view, as seen, from anyside.

Image anamorphism may vary with object-distance from the camera lens and an object at one such distance may be selected for optimum reproduction, with "u", calculated from equation 2, using the inverse of the image-anamorphism of this object. Objects at other distances are reproduced, with this degree of magnification, in correct proportions overall, but with some discontinuities at lenses' boundaries, whose scenic location varies with viewing angle. Widely varying object distances, in different quadrants of the viewpoint circle, may be accommodated in the device by a smooth variation of the 'u' dimension, calculated for images in each quadrant of the cylindroid.

The device here described may be employed in industry to provide object-periferograms and scenic-panoramas, and to provide decorative light diffusing shades.

Claims

1. A method for producing a stereoscopic reproduction in colour of an object or scenic panorama as viewed around a 3600 arc which comprises reproducing, with a camera and with an anamorphotic lens, a series of views of the object or scene, taken towards the centre of a circle from a plurality of equaliy-spaced positions around its circumference, in order to produce a measurable degree of anamorphism in the image representing each angular view. The said images are fixed by any suitable mounting, in a one-to-one relationship, behind a similar plurality of positive-focus cylindrical lenses which are abutted by their vertical, adjacent, straight edges to comprise a hollow cylindroid within which the images are mounted.The particular principal-focal-lengths of the said lenses and the particular distance behind a lens at which an anamorphic image is mounted are pre-calculated, in each case, as hereinbefore described, to produce horizontal enlargement of each image, equal in degree to its width compression, in its virtual-image which is superimposed on the other virtual-images produced in a similar manner by the lenses and images adjacent to it, so that, at their common conjugate focalplane, the overlapping edges of adjacent virtual-images mutually superimpose, substantially in pictorial register.

Thus the object so represented is observable through the group of adjacent lenses nearest the viewer, and appears to remain stationary when viewed from around the cylindroid through a succession of groups of lenses, but varies according to the angles-of-view therein represented.

2. Apparatus for producing and exhibiting the stereoscopic reproduction claimed in Claim 1, the said apparatus including (1) a cylindroid composed of, or containing, a plurality of positive-focus cylindrical lenses of any type including those with convex surfaces, or - Fresnel lenses, whose principaifocal lengths are designed to be appropriate to the series of anamorphic images to be employed therewith, and (2) a similar plurality of images which represent a series of photographed views taken towards the centre of a circle from a similar plurality of equally-spaced positions on its circumference, the said images being reproduced anamorphotically, to a size which enables them to be mounted within the cylindroid with each image accurately located at a pre-calculated distance behind a lens.

3. Means, as claimed in Claim 1 and in Claim 2, whereby a plurality of angular views, photographed from around a circle, may be exhibited as a composite field of view, seen as a single picture which varies with an observer's varying angle-of-view, as successive, vertical-strip, portions of the lenses' respective virtual-images are brought into view.