CA2355323A1

CA2355323A1 - Arrangement for the production of a scene image of a front view by incident light projection

Info

Publication number: CA2355323A1
Application number: CA002355323A
Authority: CA
Inventors: Klaus Hiller; Christhard Deter; Hans-Werner Kuhlmann
Original assignee: Individual
Current assignee: Schneider Laser Technologies AG
Priority date: 1999-11-03
Filing date: 2000-11-02
Publication date: 2001-05-10
Also published as: CN1336073A; DE19952896C1; EP1145547A3; KR20010101368A; WO2001033841A2; EP1145547A2; JP2003513322A; DE19952896C5; IL144088A0; WO2001033841A3

Abstract

The invention relates to a device for creating an image (1) for a front view by means of an incident projection, in particular for image display in a training station, in a simulator, or in an adventure world, by means of a projector (2, 3). Said device is characterised, whereby one or several projectors (2, 3) project the image of a normal view, onto a projection plan e (6) within a projection dome, by means of a refracted, brightness- and/or colour-modulated light beam emanating from a point of origin, in the form of individual lines and images. Said projectors (2, 3) are arranged in a position, such that the point of origin of the projection beams lies in fron t of the front plane of a participating person (7).

Description

500350.20138 ARRANGEMENT FOR THE PRODUCTION OF A SCENE IMAGE OF A
FRONT VIEW BY INCIDENT LIGHT PROJECTION
The invention is directed to an arrangement for generating a scene image in a front view by incident light projection, particularly for image display in a training station or in a simulator or in a virtual reality setting.
EP 0 836 169 B1 discloses a training station in which three projectors generate divided images which are imaged on a screen. The image generated on the screen is deflected via a collimating mirror onto a projection surface and shown to the acting person.
Due to the optical imaging of an image proceeding from an object plane in an image plane, the projectors are arranged well behind the back of and far above the head of the acting person. The collimating mirror is required so that a part of the scene image can be generated at all in an area which is usually perceived from a driving or navigating position.
In simulators of this kind, which are used, for example, for driver education, the projectors are arranged approximately 2 m above the head of the acting person and, e.g., approximately 1 meter behind the head of the acting person.
This is required on the grounds of optical laws relating to optical imaging and the size of the image, since it is desirable to avoid shadows on the scene image of the front view to be displayed due to the person or due to structures in a driver's compartment. Therefore, simulators of the type mentioned above are very large.
In particular, in moving systems, massive device parts are located far outside of the movement axes, so that considerable dynamic loads due to occurring acceleration forces must be brought under control. A stable and therefore massive mechanical construction is needed for this purpose, which involves considerable expenditure on mechanical or hydraulic drives.
Further, commonly used image projectors have a shallow depth of focus and unsatisfactory image resolution, especially at the edge of the image.

It is the object of the invention to reduce expenditure for the realization of training installations, simulators or virtual reality settings and to improve the realism of a front view of a generated scene image. The invention should be suitable for simulators with moving systems (flying screen) as well as for S simulators without moving systems (fixed screen).
In an arrangement for generating a scene image of a front view by incident light projection, particularly for image display in a training station or in a simulator or in a virtual reality setting by means of a projector, the above-stated object is met according to the invention in that at least one projector writes the scene image of the front view on a projection surface with a brightness-modulated and/or color-modulated light bundle which is deflected in two dimensions proceeding from a point of origin within a projection cone and each projector is arranged in such a way that its point of origin is located in front of an acting person in the viewing direction of the acting person.
The advantage in arranging the projector in front of the acting person consists in that possible shadows on parts of the image caused by structures or by the observer are drastically reduced. The projector can accordingly be arranged closer to the eye level of the observer. In particular, this has the advantage that image distortion is reduced. If it is desirable to eliminate these relatively minor image imperfections as well, the required correction steps can be realized at the scene image at a comparatively small expense. The principle of the invention can also be realized by a plurality of projectors, e.g., two or three, when the scene image is composed of partial images.
While only one acting person is mentioned in the description, this does not mean that the invention is limited to applications involving only one individual person. Rather, the principle of the invention can also be applied when there are two persons, such as a driver and passenger, or a group of persons.
Projectors which write the scene image on a projection surface with a deflected brightness-modulated and/or color-modulated light bundle proceeding from a point of origin in two dimensions within a projection cone are particularly advantageous. They are also known as "laser projectors." Projectors of this kind are fundamentally distinguished from common imaging projectors such as LCD

projectors or CRT projectors with respect to the imaging principles of the light bundle. Since a red-green-blue light bundle is deflected in a "laser projector" for writing the image points of a line and no conventional optical imaging is carried out in an image plane proceeding from an object plane internal to the device, considerably larger projection angles can be achieved and the distance between the projector and the projection surface can be freely selected within wide limits.
Extensive geometric corrections can be carned out with a projector of the kind mentioned above, so that image distortion due to oblique projection or as the result of the shape of the projection surface can be corrected to a great extent.
Further, the image of a projector of this type is sharp within a very large depth range, so that the projection distance from the projection surface can vary extensively. A projector of this type and the corresponding correction possibilities for the display of images are described in DE 197 37 374 C2. The scene image is corrected for the position of the principal point or eyepoint relative to the projection surface, wherein an image recording camera or an image computer records and/or calculates the scene image for this eyepoint. When using transformation optics, for example, according to DE 43 24 849 C2, the point of origin of the projection is the outlet pupil of the transformation optics; otherwise, when no transformation optics are used, it is the deflection point of the line deflection through a polygon mirror.
The projector is advantageously arranged in a position in which the point of origin of the projection rays is located in front of (ventral) the frontal plane in which the eyepoint of the acting person is located. In this position, the area of possible shadowing of projection rays by the acting person or by a driver's compartment is very slight or even nonexistent.
A projection surface having at least one center of curvature is advisably used in the arrangement. With a cylindrical or curved projection surface, the scene image of a frontal view can be shown in a particularly favorable manner because the field of view of the acting person can be completely filled with a realistic image content. In particular, the projection surface can be the inner surface of a semicircular body, for example, a sphere or a parabolic semicircular body.
In an advantageous further development of the invention, the geometry is selected in such a way that the eyepoint of the acting person or the point of origin of the projection rays is located in a center of curvature of the projection surface. In this case, the occurring visible geometric image distortions are very slight, so that there are very few required corrections in the scene image to be displayed or these corrections can even be omitted. In any other position, more extensive image distortion occurs which can only be corrected at increased technical expense and sometimes with a loss of quality of the image display.
When the projection surface has more than one center of curvature, as is the case in a parabolic or semicircular projection surface, it is advisable for the reasons mentioned above that the point of origin of the projection rays is located in a first center of curvature and the eyepoint of the acting person is located in a second center of curvature of the projection surface.
Due to the respective spatial arrangement of structures, e.g., of a simulator compartment and of the projector, it is not always possible to position the projector or the acting person in a center of curvature. In this case, for low image distortion, each projector should be arranged in such a way that its projection cone intersects a center of curvature with a selected plane. The projector has a principal projection axis which is determined by the intersection line of two planes: a horizontal plane defined by its parallel position relative to the line direction in the center of the image height of the projection cone and by the point of origin of the deflected light bundle, and a vertical plane which is determined by its vertical position relative to the line direction in the center of the image width of the projection cone and by the point of origin of the deflected light bundle. Low image distortion is achieved when the vertical plane or the horizontal plane or both planes contain/contains one or both centers of curvature.
Further, the expenditure on correction for the projection is also substantially reduced when the acting person is located in a defined position relative to the projection surface. This is the case when the median plane and/or the frontal plane through the eyepoint of the acting person contain/contains one or both centers of curvature.
In particular, for projections in which a very large horizontal viewing angle is to be filled up with a scene image, the scene image is advisably not shown with an individual projector but, rather, is halved or quartered and each of these divided up images is associated with an individual projector. Therefore, at least two projectors are preferably arranged in such a way that the principal projection axes of these projectors intersect at a point located to the rear (dorsal) of the acting person and are oriented relative to one another such that two generated images contact without transition at their corresponding side edges on the projection surface. The point of origin of the projection rays is located in front of (ventral) one of the frontal planes of the acting person.
One of the designated planes, the horizontal plane or the vertical plane, must be identical for the projectors in order for the principal projection axes of the projectors to intersect. The projectors are arranged and oriented relative to one another in such a way that two adjacent images adjoin one another seamlessly at their common side edges. Due to the correction possibilities described in DE

374 C2, the divided images of the projectors can be arranged next to one another seamlessly in a pixel-exact manner and then appear unified on the projection surface to form a scene image. An overlap area such as in CRT projectors, for example, is not required.
When there are a plurality of projectors, it is advantageous when the intersection point of the principal projection axes coincides with a center of curvature of the projection surface. In this case, the image distortion is very low and any corrections which may be necessary require very little effort.
In the case of a spherical or semispherical projection surface, the intersection point of the principal projection axes is advisably located in the center of curvature of this projection surface. This minimizes image distortion.
The advantage of minimized image distortion is also achieved when the vertical plane or the horizontal plane of each projector includes one or both centers of curvature of the projection surface. In this case, the intersection of the principal projection axes does not lie in the center of curvature.
In a further development of the invention, the point of origin of the projection rays of each projector lies transversely less than 1 meter above (cranial) the eyepoint of the acting person in relation to the transverse plane through the eyepoint of the acting person.

As a result, the headroom of a training station, simulator or virtual reality setting is reduced by a factor of 0.3 to 0.5 compared to known arrangements working with incident projection (front projection). The structural size is now determined essentially only by the magnitude of the curved projection surface.
In this respect, the structural height is given approximately by the image height and the width is given by a horizontal radius of the semicircular projection surface.
Due to the considerable reduction in the structural size, moving systems have considerable advantages with respect to the dynamic behavior of the moving systems because, for one, the mass can be kept smaller as a whole and, on the other hand, the center of mass lies closer to the movement axes. The projectors are advantageously arranged at supporting parts of an outer facing of a simulator compartment. The simulator compartment serves as an outer shell in which are arranged, for example, a driver's compartment, one or more projectors, and one or more projection surfaces associated with these projectors. With one projector, which works with a writing light bundle, a substantially larger projection angle can be realized compared with a conventional object-magnifying image projection. This has the advantage that, for example, a 180-degree projection can be realized with two projectors instead of with four CRT projectors.
In another advantageous configuration of the arrangement, the transverse plane through the eyepoint of the acting person intersects the projection surface and this intersection line, from the point of view of the acting person, lies in the range of +/- 10° of another intersection line which is generated through the horizontal axis of the projector on the projection surface. In this way, it is ensured that the acting person enjoys optimum visual coverage approximately in the center of the image and can take into account the real viewing conditions, for example, from the driver's position in a locomotive or from the driver's cab of a truck.
The invention is described more fully in the following with the example of a locomotive simulator with reference to the drawings.
Fig. 1 shows a simulator with incident light projection according to general prior art as viewed from the viewing plane of the acting person;

Fig. 2 shows a simulator according to Fig. 1 in a top view of the acting person;
Fig. 3 shows a simulator with a projector for incident light projection for generating a scene image in the viewing plane of the acting person;
Fig. 4 shows a simulator according to Fig. 3 in a top view of the acting person;
Fig. 5 shows a simulator similar to Fig. 3, but with two projectors;
Fig. 6 shows a simulator similar according to Fig. 5 in a top view of the acting person; and Fig. 7 shows a simulator similar to Fig. 3 in a top view of the acting person.
Fig. 1 shows a simulator for locomotive driver training, according to the prior art, with a view of an acting person 7. Fig. 2 shows a top view of the simulator according to Fig. 1. A movement system is not shown in the Figures for the sake of clarity. Also, a driver's compartment 10 is only shown schematically. It is intended to represent the driver's cabin of a locomotive. Two CRT
projectors 2 and 3 are used for projecting a scene image 1, each of which generates an image 4 and 5 on a projection surface 6. The two images 4 and 5 are combined to form a scene image 1 with a horizontal dimension of 90° and a vertical dimension of 30° in relation to the eyepoint of the acting person. These known projectors which work on an image-projecting principle deliver correspondingly large, sharp and undistorted images only from a relatively great projection distance, for which reason the projection distance must amount to approximately 4 m with an image height of about 2 m. Further, the projection surface must have the most uniform possible distance from the projector because of the limited depth of focus.

- g -Since the structures of the driver's cabin can cause shadows on the images, the projectors must be arranged correspondingly high above the driver's cabin. In order to circumvent this, deflecting mirrors are used according to the prior art as is known, for example, from EP 0 836 169 B 1. As a result of these conditions, the projectors are arranged more than 1 m behind and more than 1 m above the position of the acting person 7. This is particularly disadvantageous when the projectors 2 and 3 are subject to the dynamics of the simulator in a flying-screen system. In this case, relatively massive projectors are located very far from the movement axes.
Further, with CRT projectors, the projection cones generating the images 4 and 5 must overlap by approximately 2° to 4° in order to achieve the desired seamless joining of images 4 and S by means of edge blending, as it is called. Typically, for this purpose, there is an intersection point S of the principal projection rays which, as can be seen in the example according to Fig. 1 and Fig. 2, is located far to the rear of the position of the acting person and far above the head of the acting person, and the projection rays intersect.
In the following Figures, identical reference numbers designate the same elements as in Fig. 1 and Fig. 2. Also, the dimensional ratios correspond to one another in order to illustrate the advantages of the invention.
Fig. 3 shows an arrangement according to the invention for generating a scene image with an individual projector 2 with a view of the acting person 7. Fig. 4 shows the arrangement according to Fig. 3 in a top view. In this case, an individual projector 2 is used to show a scene image which is larger than that in Fig. 1. The projector is not an imaging projector, but rather writes the image 4 on the projection surface 6 with a deflected brightness-modulated and/or color-modulated light bundle from a point of origin in two dimensions within a projection cone. However, a plurality of light bundles can also be written simultaneously as is shown in DE 197 26 860 C 1.
These projectors are also known as laser projectors. An example of a projector of this kind is described in DE 197 37 374 C2. The steps by which image corrections can be carried out are explained in detail in the latter reference.

The use of laser light for projection is not compulsory; rather, a collinear light bundle which can also be obtained from another light source, e.g., a luminescent diode, is sufficient for image display. In this case, as can clearly be seen from Fig. 4, a projector 2 which writes an image in two dimensions with one or more collinear light bundles is arranged in front of (ventral) a frontal plane of the acting person 7. Due to the shortened projection distance and the very extensive possibilities for image correction even at large projection angles, the projector 2 is arranged at an appreciably shorter distance above the acting person 7 in comparison to Fig. 1 and projects obliquely onto the projection surface 6 proceeding from a position in front of the center of curvature M.
Fig. 3 shows the substantially reduced structural height of the simulator compared with Fig. 1, which has an especially positive result for the dynamics of the system when it is moved, for example, in a simulator according to the flying screen principle. In Figs. 3 and 4, the center of the spherical projection surface 6 lies in a vertical plane 8 of the projector 2 and in the median plane of the acting person 7. This positioning of the projector 2 and of the acting person reduces the expenditure on correction for the projection of a distortion-free scene image 1. However, there are additional advantages for image projection when the projector 2 or the acting person 7 is located as close as possible to the center of curvature M of a curved projection surface 6. In the arrangement of Fig. 4, this can be achieved in that the projector 2, the acting person 7 and the driver's cabin 10 are displaced in the direction of the center point M in such a way that the point of origin of the projection is identical to the center point of the projection surface.
This modification is shown in Fig. 7 and leads to a greater structural depth which corresponds roughly to Fig. 2. However, no disadvantages result from this, since the structural height of the simulator which is reduced compared to Fig. 1 is retained.
Fig. 5 shows the arrangement according to the invention for the generation of a scene image with two projectors 2 and 3 with a view of the acting person 7. Fig. 6 shows the arrangement of Fig. 5 in a top view. The projectors and 3 are again arranged in front of (ventral) a frontal plane of the acting person 7.
Further, the principal projection axes of the projectors intersect in the center of - 1~ -curvature M of the semispherical projection surface 6. The center of curvature M
lies farther in the frontal plane containing the eyepoint of the acting person. As can clearly be seen in comparison to the arrangement in Fig. 1 which is shown in the same dimensional ratios, the projectors are arranged at an appreciably lower height above the eyepoint of the acting person 7. Further, a comparison between Fig.
2 and Fig. 6 shows that the projectors 2 and 3 are clearly located in front of the eyepoint AP of the acting person 7. In practice, the projector 2 and 3 can be arranged directly above a front windshield of the driver's cabin 10, for example, in a locomotive simulator. Shadows caused by the driver's cabin are accordingly completely eliminated. Fig. 5 also shows that the horizontal plane 9 containing the eyepoint AP
of the acting person 7 lies approximately in the vertical image center of the projected scene image 1.
Although the description mentions only one or two projectors, the principles discussed in relation to the arrangement of two projectors, the acting person and the projection surface also hold true in an analogous manner for three, four or more projectors which form a scene image 1 from three, four or more partial images.

Claims

1. Arrangement for generating a scene image (1) in a front view by incident light projection, particularly for image display in a training station, a simulator or a virtual reality setting, characterized in that at least one projector (2, 3) writes the scene image (1) of the front view on a projection surface (6) with a brightness-modulated and/or color-modulated light bundle which is deflected in two dimensions, proceeding from a point of origin, within a projection cone, and each projector (2, 3) is arranged in such a way that its point of origin is located in front of an acting person (7) in the viewing direction of the acting person (7).

2. Arrangement according to claim 1, characterized in that the projector (2, 3) is located in front of a frontal plane containing the eyepoint (AP) of the acting person (7).

3. Arrangement according to claim 1 or 2, characterized in that the projection surface (6) has one or two centers of curvature (M).

4. Arrangement according to claim 3, characterized in that the eyepoint (AP) of the acting person (7) or the point of origin of the projection rays lies in a center of curvature (M) of the projection surface (6).

5. Arrangement according to claim 3, characterized in that the point of origin of the projection rays is located in a first center of curvature and the eyepoint of the acting person is located in a second center of curvature of the projection surface (6).

6. Arrangement according to claim 3, characterized in that the at least one projector (2, 3) has a principal projection ray which is characterized by the intersection line of a horizontal plane (9) defined by its parallel position relative to the line direction in the center of the image height of the projection cone and by the point of origin of the deflected light bundle, with a vertical plane (8) which is determined by its vertical position relative to the line direction in the center of the image width of the projection cone and by the point of origin of the deflected light bundle, wherein one of these planes (8 or 9) contains a center of curvature (M).

7. Arrangement according to claim 3, characterized in the median plane and/or the frontal plane through the eyepoint (AP) of the acting person contains a center of curvature (M).

8. Arrangement according to claim 1, characterized in that two or more projectors (2, 3) are provided, the principal projection axes of these projectors intersect at a point (S) located to the rear of the acting person (7), and in that the projectors are oriented relative to one another such that two generated images (4, 5) located next to one another contact without transition at their side edges on the projection surface (6).

9. Arrangement according to claims 3 and 8, characterized in that the intersection point (S) of the principal projection rays coincide with a center of curvature (M) of the projection surface (6).

10. Arrangement according to claim 9, characterized in that the intersection point (S) of the principal projection rays lies in the center of curvature (M) of a spherical or semispherical projection surface (6).

11. Arrangement according to claim 8 and claim 6, characterized in that the vertical plane (8) and/or the horizontal plane (9) of each projector (2, 3) contain/contains a center of curvature (M).

12. Arrangement according to claim 1 or claim 8, characterized in that the point of origin of the projection rays of each projector (2, 3) is located less than 1 meter above the eyepoint (AP) of the acting person (7) in relation to the transverse plane through the eyepoint (AP) of the acting person.

13. Arrangement according to claim 12, characterized in that the transverse plane through the eyepoint (AP) of the acting person (7) intersects the projection surface (6) and this intersection line, from the point of view of the acting person (7), lies in the range of +/- 10° of another intersection line which is generated through the horizontal axis (9) of the projector (2, 3) on the projection surface (6).