EP1023570B1 - Simulator - Google Patents

Description

The present invention relates to a simulator for simulating the view of a scene from a pre-determined observer station.

Simulators are well known in which an image of the scene to be simulated is viewed from a pre-determined viewing station via a mirror, the mirror, image and viewing station being positioned such that light reflected by the mirror to the viewing station from the image is substantially collimated. Such displays may be used for example in infantry weapons training simulators. Typically, back projection screens are positioned behind a fixed structure in front of which the trainee stands. Image projectors also located behind the fixed structure project images onto the screens. A concave mirror is located such that the image presented on the screens can be viewed via the mirror by the trainee.

It is often desirable to he able to train a group of trainees using a single simulator. In such circumstances it is highly advantageous if the mirror can be of large dimension, for example having a height of the order of two metres and breadth of the order of six metres, such that the mirror subtends an angle in the horizontal direction of the order of 50° when viewed from the trainee viewing station. Mirrors of such dimensions can be fabricated from a single film of reflective plastics material the edges of which are secured to an appropriately shaped frame, the space behind the film of plastics material being evacuated to suck the mirror into the desired geometrical shape. Unfortunately such a structure is so large that it cannot be manoeuvred into position in many buildings in which displays are required. Furthermore, it is relatively difficult to build mirrors of such dimensions with the necessary tight geometrical tolerances. Accordingly, large mirrors are usually assembled by abutting a series of relatively small mirrors edge to edge.

With available sucked mirror structures, it is not possible to maintain the necessary geometry of the reflective material right up to the mirror edge and therefore there is a very perceptible edge effect at the joint between two adjacent mirrors. This significantly reduces the perceived realism of a single image projected so as to overlap the abutting edges of two mirrors.

It is accepted wisdom in the simulator industry that the last thing one wants to consider is positioning anything between the trainee and the mirror surface. An object so positioned is visually very distinct from the image perceived via the mirror and can be expected to dramatically reduce the perceived realism of the viewed image.

It is an object of the present invention to obviate or mitigate the problems outlined above.

According to the present invention, there is provided a simulator for simulating the view of a scene from a pre-determined observer station, comprising at least one image source for presenting at least one image representing the scene, and a mirror positioned such that a reflection of the or each presented image can be viewed from a pre-determined viewing station, the mirror, the or each image source and the viewing station being arranged such that light reflected by the mirror to the viewing station from the or each image source is substantially collimated and represents the appearance of the scene from the viewing station, and at least one opaque and non-reflective object positioned on or immediately in front of the mirror, characterised in that the mirror is formed from at least two segments edges of which abut, the object being positioned to cover the abutting edges and having an appearance appropriate to the presented image so as to contribute to the scene.

The present invention relies upon the realisation that for certain scenes it is acceptable for objects to be relatively close to the viewing station. Providing those objects are positioned such that reflections of them cannot be perceived in the mirror, the overall perceived quality of the image is not significantly reduced. By positioning such objects so as to overlie portions of the mirror which do not have the optical characteristics necessary to reflect light in a manner consistent with the rest of the mirror surface, the perceived degradation of image quality resulting from edge effects between adjacent mirrors can be avoided.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a schematic perspective representation of components used in a known infantry weapons training simulator.

Figure 2 is a vertical section through the components showed in Figure 1; and

Figure 3 shows the positioning of an object on the surface of the mirror of Figures 1 and 2 so as to cover a portion of that mirror which is defined by abutting edges of two mirror sections.

Referring to Figures 1 and 2, the illustrated arrangement comprises a mirror 1 made up from four substantially identical mirror sections the abutting edges of which are represented by lines 2. Each of the mirror sections comprises a frame 3 defining four curved edges to which a film of reflective plastics material is attached. The frame and film together define an enclosure which is evacuated so as to stretch the plastics film which is sucked into a shape determined by the shape of the edges of the frame and the differential pressure across the plastics film.

The optical quality of sucked film mirrors of this type is relatively high except immediately adjacent the peripheral edges of the frame.

The mirror 1 is viewed from a viewing station in from of a fixed structure 4 which supports four projections screens 5. Images are projected onto the screens 5 from four projectors 6. The projectors 6, screens 5 and mirror 1 are located such that light reaching an observer at the viewing station appears to come from infinity.

Highly realistic images can be viewed with the structure shown in Figures 1 and 2 except when the light reaching the viewer comes from a portion of the mirror immediately adjacent the abutting edges 2. The presented images are as a result perceived as being made up from four separate sections of high quality separated by regions of relatively low quality adjacent the abutting edges 2. These regions of low quality significantly reduce the perceived quality of the overall image.

In accordance with the present invention, the problem described above resulting from the optical inaccuracies of the mirror adjacent the abutting edges 2 can be overcome by the simple expedient of placing an opaque object over the abutting edges of the four mirror sections. Figure 3 represents one such object 7 having the appearance of a tree trunk. The side of the object remote from the observer is either adhered to or very close to the surface of the mirror so that no reflection of that side of the object can be perceived by the viewing station. The object is clearly very close to the observer but does not impair the perceived quality of the image providing its appearance as appropriate to that image, for example, in an infantry weapons training simulator it is possible for it to be reasonable in a simulated scene for an object such as a tree to be close to the observer station the view from which is to be simulated. Movement of the observer within the area of the viewing station will of course result in perceived movement between the object and the represented scene but this of course is consistent with what happens in reality when an observer moves his head to look behind an object placed in front of him. Thus the overall realism of the image is maintained.

Claims (2)

1. A simulator for simulating the view of a scene from a pre-determined observer station, comprising at least one image source (5) for presenting at least one image representing the scene, and a mirror (1) positioned such that a reflection of the or each presented image can be viewed from a pre-determined viewing station, the mirror (1), the or each image source (5) and the viewing station being arranged such that light reflected by the mirror (1) to the viewing station from the or each image source is substantially collimated and represents the appearance of the scene from the viewing station, and at least one opaque and non-reflective object (7) positioned on or immediately in front of the mirror (1), characterised in that the mirror (1) is formed from at least two segments edges of which abut, the object being positioned to cover the abutting edges (2) and having an appearance appropriate to the presented image so as to contribute to the scene.
2. A simulator according to claim 1, wherein the image source is a back projection screen (5) onto which the image is projected.

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