Patent Publication Number: US-8118434-B2

Title: Projecting an animated object and concurrently moving the object&#39;s projection area through an animation pattern

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 12/133,967, filed Jun. 5, 2008, entitled “Method and System for Projecting an Animated Object and Concurrently Moving the Object&#39;s Projection Area Through an Animation Pattern,” which is hereby incorporated by reference into this application. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates, in general, to projection and display systems and technology, and, more particularly, to projection systems adapted to display images or characters with high resolution and brightness on a display surface or screen such that the images or characters are animated or move on the surface or screen. 
     2. Relevant Background 
     In theme parks and other entertainment venues, guests and visitors are often entertained by movies and animated films. For example, queue areas may include display screens where a short animated film is shown to make a wait more enjoyable and may be used as part of the overall show or for advertising upcoming events, other attractions, and available services and products. It is desirable for these movies and animated works to be shown in high resolution or with good quality, and this is typically not a problem in environments where the lighting, the distance from the projection screen or surface is easily controlled, and other display or projection parameters may be easily controlled or changed to suit the needs of the display. 
     However, there are many applications where the designers of a movie or animated film display have to overcome challenging design parameters. For example, theme and amusement parks may include rides in which the guests or passengers are moved through a show area in vehicles and due to space constraints, a display or projection screen has to be placed very close to the side of the vehicle. As a result, the displayed image may only be several feet from the viewing passengers or guests, and such closeness to a projection screen can make it very difficult to provide high quality images (e.g., images with relatively high resolution and brightness). For example, a projection or display screen may be similar in size to those found in movie theaters, and use of a single projector such as one with a resolution of 1024 by 768 pixels or the like would result in the image appearing grainy and dull to viewers due to the relatively large pixel size (e.g., similar to sitting closer than the front row to watch a movie at a theater). 
     In other applications, it may be desirable to display animated characters or movie/film images to select groups of the riders or guests in the vehicles (such as to guests as their vehicle passes a portion of the display or projection screen/surface), and it is difficult to provide high quality imagery on only a portion of the screen or provide characters that can move with the vehicle. Another problem facing many ride designers is how to maintain a desired level of darkness or blackness on unused portions of the screen such as when the character is only located in a portion of the large screen. Typically, a single projector will project some lower level of light onto these non-projected areas causing the screen about the displayed image to be undesirably gray or illuminated. 
     The problem may be stated more generally as involving media playback on a large screen, and the media playback may include animated characters, such as animals, people, or other characters from an animated work or film. The use of a single projector does not provide enough pixels or a high enough resolution to create an acceptably sharp image for an audience located only a few feet away (e.g., as may be viewed through an opening, a window, or a porthole of a ride vehicle such as may be provided in an underwater ride like a submarine, a spaceship, and many other vehicles or in non-ride applications). 
     In an attempt to overcome the problems with using one projector for a large screen, some projection systems have been created that utilize numerous projectors that each project on a smaller subset of the display surface. Each of these projectors typically has to be arranged to overlap or feather their edges to create a continuous image. High resolution can be achieved by synchronizing all of the playback devices providing images to the projectors. In one exemplary implementation, a tiled projector system was utilized that included 90 projectors with 90 synchronized, high definition playback devices such that these projectors acted together to display a movie or a set of animation images (e.g., at a rate of 24 to 30 frames per second or the like). In other words, each projector was used to display images on a much smaller area of the screen to provide an adequate resolution or number of pixels within each smaller area (e.g., onto about 1/90 of the screen area in this example). While useful in some applications, the use of numerous projectors to display a movie typically is very expensive, and it is complex to design the physical arrangement of the projectors and the control and feed/input of the playback devices (e.g., costly and time consuming to produce the input media and to blend all of the projected images together to provide a single high resolution image). During use to display a movie or animated work with a smaller number of character images, most of the projectors are projecting nothing and only project a character image when it passes through a corresponding projection field (e.g., the projector remains on even when not in use to project an image and often creates an illuminating effect that undesirably leads to a graying effect). 
     Hence, there remains a need for improved visual display techniques and systems such as for creating an animated character or image on a display surface (such as projection screen or the like) that has high quality even when viewed from small distances (e.g., less than about 10 feet and often less than 5 feet). Preferably such techniques and systems would be inexpensive to install, would require minimal maintenance, and would be configurable to position into small or limited physical spaces. Also, it would be preferable if such techniques and systems would provide a bright image while providing, in some applications, very dark or black surrounding areas such as to hide or not illuminate surrounding portions of the display surface or screen. 
     SUMMARY OF THE INVENTION 
     The present invention addresses the above problems by providing projection systems and methods adapted for projecting or displaying images of characters or objects using a projector and a mirror assembly configured to reflect the projector output onto a projection surface or screen within a projection area or projected area/field that represents a fraction of the total screen area or size. The media playback through the projector may be animated characters or objects and may be displayed upon a large screen. To provide a desirable resolution with the media playback, the character/object may be the only content in the projection area and the size of the projection area is chosen to be a fraction of the projection screen or its surface area (such as a 1 to 2 foot diameter circle projected upon a surface that is up to 30 to 40 feet or more in length and up to 5 to 40 feet or more in height). The projection area is moved over an animation or projection pattern or path so as to allow the character or object in the projection area to move over all or portions of the large projection surface or screen (e.g., to provide a second level of animation that can be combined with animation/movement of the object within the projection area). In other words, the movement of the object as projected is compounded by the movement of the projection area on the projection surface or screen. In one embodiment, robotically controlled or motor driven mirrors redirect the image from a video projector so as to precisely recreate the animators&#39; original character movements intended for a large area (e.g., the character was animated with intention of a single, stationary projector projecting the image on the large screen or display surface). All of the resolution of the single projector is directed only to where the character is located as the character is the only projected item of interest (i.e., within the projection area/field), and effective resolution of the entire screen increases by many times (e.g., 10 or more times or the like) when compared with using that same projector to project the same character onto the entire screen surface. The use of a single projector to provide an animated character/object saves cost and complexity relative to systems using numerous projectors (e.g., 90 or more projectors) as well as simplifying media production. Further, since light is only (or substantially only) projected upon the small projection area, the black or non-projection areas may be maintained as truly black. 
     More particularly, a projection assembly is provided for displaying images on a relatively large surface with motion or animation and with high resolution and brightness. The assembly includes a projector that receives an input image stream and projects images. A mirror assembly is positioned proximate to the projector outlet and has one or more mirrors that are positionable to reflect the projected images onto a display surface at a plurality of positions. The assembly further includes a motor controller assembly that positions the one or more mirrors based on a set of position data that define the plurality of image positions. The image positions define an animation or projection pattern on the display surface for at least one predefined portion of the input image stream. 
     The predefined portion may be an image of a character and the plurality of positions may be spatial coordinates for the character image on the display surface. The projected images may be provided in a projection area or field that is a fraction of the size of the display surface, such that the resolution and output light of the projector are concentrated on the display surface within this projection area (which may be less than about 9 square feet in some embodiments and typically less than about 2 to 4 square feet). In some cases, the character image may have a size that at least in some frames or portions of the input image stream is about the same as or equal to the projection area. The spatial coordinates may be defined in a source media for the input image stream that is adapted for projecting over most or the entire display surface area (e.g., an animated work adapted for a large projection screen). The character may be animated within the projection area itself (such as by changes in the character between frames of the input image stream) while also (concurrently in some cases) being animated by movement of the one or more mirrors to move the projection area along the animation pattern over a display time period (e.g., the display time period may equal the length of the input image stream and the positions of the projection area correspond to one or more frames of the input image stream as position information may be provided for or derived from the frames of the source media). 
     In some embodiments, the mirror assembly includes an X-axis mirror and a Y-axis mirror that are each pivotable about an axis. The X-axis mirror and the Y-axis mirror are offset from each other and their axes may be in differing, parallel planes and be orthogonal to each other. The motor controller assembly may include a pair of DC servo motors that are linked to the mirror axes (or pins/shafts attached to the mirrors). The motors are operated by the controller assembly to pivot the mirrors independently (but often concurrently) to move the projected images through the plurality of positions that define X-Y coordinates on the display surface so as to move or animate the projected images by moving them along the animation pattern. The positions of the animation pattern may be thought of as defining a number of X-Y coordinates (or X-Y pairs) that is larger than the number of frames in the input image stream, whereby motion of the projected images (or a character in a projection area/field) along the animation pattern or trajectory appears smooth and/or continuous to a viewer, e.g., more realistic motion than is achievable with changes between frames of an animated work as there are typically 24 to 30 frames per second in such works while the motor controller may operate the motors at interpolated rates up to or exceeding 1000 frames per second. 
     The input image stream may be generated from a source media that may provide a character image at the plurality of positions on the display surface (e.g., the source media may be adapted to use the whole or large portions of the display surface). The input image stream may be distorted relative to the source media (or the character image within the source media may be predistorted) to account for or limit keystone distortion caused by using the moving mirror(s) to display projected images at offset angles from a perpendicular projection position (e.g., a center of the screen or display surface or the like). It should be understood that there are generally two disparate distortions involved with using projection assemblies that should be considered and addressed: media distortion and motion distortion. To address these distortions, in some embodiments, the media is pre-distorted to compensate for keystone, rotation, and/or scale error introduced by the mirror positions, and the XY position data is, in some preferred embodiments, adapted to allow for the increased amount of position change as the image is projected her from center (relative to the location of the projection assembly or its outlet). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a top view of a ride/show system including an animated projection area or moving mirror projection assembly shown generally in functional block form; 
         FIG. 2  is a partial side view of the ride/show system of  FIG. 1  further showing use of a projector and XY mirror assembly of the invention for projecting high resolution images within a projection area/field that is a fraction or subset of the available projection screen or surface and for moving the projection area along a path or pattern that is defined or driven by a source media (e.g., XY coordinates of a center of rotation of the projection area is moved according to an image (or character) movement or position within the source media); 
         FIG. 3  illustrates a projection system of an embodiment of the invention showing use of projection assembly with moving mirrors to move a projected or projection area through a media-driven animation pattern upon a display surface (such as a rear or front projection screen); 
         FIG. 4  illustrates a projection system similar to that shown in  FIG. 3  but using more than one projection assembly to provide two images/characters of a media or image source in distinct and separate projected or projection areas that may be moved in unique animation patterns that may be synchronized to have the images/characters interact or may be unsynchronized and/or unrelated patterns; 
         FIG. 5  is a side view of a moving mirror projection assembly shown functionally with a side of a mirror housing removed to illustrate operation; 
         FIG. 6  is an end view of the assembly of  FIG. 5  again with a wall/side removed from the housing better illustrate internal operations of the assembly to provide a moving or animated projection area that have numerous X-Y coordinates follow a predefined pattern or a pattern created in response to input stimuli such as motion sensor signals); 
         FIG. 7  illustrates another embodiment of a moving mirror projection assembly similar to the assembly of  FIG. 5  but including folding mirrors to redirect projector output images to allow desired configuration of the mirror housing (e.g., reduce its length); 
         FIG. 8  illustrates a mirror axis position controller of an embodiment of the invention such as may be used in a projection assembly to control operation of the mirror positioning motor to obtain desired X-Y coordinates of an output image of a projector; and 
         FIG. 9  is a graph for use in determining arc-tangent corrections for rays reflecting from mirrors in a projection assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Briefly, embodiments of the present invention are directed to projection or display systems, and associated methods, for projecting or displaying an image or character that is animated both within a projection area/field and also by the movement of the projection area/field across a larger display screen or surface (such as a front or rear projection screen, a flat wall, a floor, or a ceiling, or the like). Animation of the image or character is provided by projecting into the projection area/field frames of an animated film/work (e.g., 24 to 30 frames including the image or character) or of a more conventional video or movie (e.g., live action video of a subject with the terms “character” or “image” being broad enough to cover nearly any object that may be animated or moved across a display screen including normally inanimate objects like a ball, a comet, or the like). 
     Animation or movement of the projection area itself is achieved by pairing output images of a projector with an XY mirror assembly that responds to an input pattern or trajectory to move one or more mirrors to change the X-Y coordinates of the projection area on a display surface (e.g., to move the center of rotation or center of the projection area about the display surface). The input pattern being defined or driven by the position of the particular character or object within a source media (e.g., an animated film/work, live action film/video, or the like). For example, the mirror assembly may include an X-axis mirror and a Y-axis mirror that each may be rotated about an axis by a motor so as to project the image from the projector that strikes and is reflected from both of the mirrors to a particular location on a display surface or screen corresponding to a position of the character within the source media. In this manner, the projected area may be a fraction of the size of the overall projection surface or screen so as to concentrate the light onto this portion of the display surface, and, significantly, to allow all of the resolution (or pixels) of the projector to be used for the character (or for the smaller projection area without a significant number of pixels not being used or wasted). In other words, the area about the projection area may be kept black (or be a true black area rather than a gray area as is the case when projectors project unused pixels upon parts of a full display surface) with the projector light directed by the X-Y mirror assembly just to the projection area, and the resolution of the character/image being animated within the projection area is significantly higher. For example, the image may be provided in a resolution of 1024 by 768 pixels and the projection surface/screen and projection area may be selected such that the projection area is about 1/10 to 1/20 (or less) of the area of the projection screen. In this case, all or most of the 1024 by 768 pixels would be provided or projected within the projection area rather than only 1/10 to 1/20 (or less) of these pixels being in such an area if the projector was used to project onto the entire area of the projection screen at one time (as in common display systems). As a result, the image within the projection area/field appears to be of a very high quality because it has high resolution, higher brightness levels, and higher contrast with adjacent areas of the projection screen which may be truly black. 
       FIGS. 1 and 2  illustrate a ride or show system  100  that makes use of projection concepts of embodiments of the invention to provide a high quality projected image on a projection surface that, in this case, is positioned proximate to the audience or viewers (such as within 10 feet and often a distance less than 5 feet). The close audience positioning is acceptable in this case because the resolution of the projection area is quite high (such as 1024×768 pixels within a 1 to 2 foot diameter projection area or another useful resolution and/or projection area size/shape may be used). As shown, the ride assembly  100  includes a ride vehicle  105  for carrying an audience or viewers of a display that is moving along a path or track as shown with arrows  107 . In this case, the vehicle is shaped like a submarine such that the viewers/audience have their view of the exterior area blocked by walls except for viewing windows or portholes  220  which allows the line of sight or viewing area to be relatively tightly controlled to an area outside the window or porthole  220 . The vehicle  105  is caused to ride within water  214  with an upper portion being exposed to air  212  in a vehicle travel area or a show portion  210  of ride or show system  100 . Images projected toward the viewers pass as shown with arrows  231 ,  233  through the water, which provides an effect of being in an actual submarine. Of course, the use of water  214  or portholes  220  are not requirements of the invention as the invention may be implemented in ride systems with open vehicles such that the audience may more freely view a projection surface and projection areas displayed thereon. 
     In the ride system  100 , the riders within the vehicle  105  are entertained with a show that includes an animated character(s) that moves or swims outside the portholes  220 . To this end, the vehicle  105  is separated by a show wall  110  from a projection surface  114 , which in this non-limiting case is a rear projection screen positioned near a transparent or at least translucent window  112  in the wall  110 . A moving mirror projection assembly (or animated projection area assembly)  120  is provided behind the RP screen  114  and functions, as described in detail below, to project a projection area/field onto the surface of the RP screen  114  and to move this projection area/field through a desired projection pattern, path, or trajectory that is defined or driven by a source media for a character/image that is projected within the projection area/field. Note, the screen or projection surface may also include a front projected screen or surface (e.g., a front projection screen). The distance, d viewer , between the porthole  220  and the RP screen  114  may be relatively short such as 3 to 10 feet or the like, which is often desirable due to tight space constraints of ride systems like system  100  in practice and which is acceptable with the high resolution provided by the projection assembly  120 . 
     The RP screen  114  may provide a display or projection surface that is relatively large such as a width, W screen , of 20 to 40 feet or more and a height, H screen , of 5 to 15 feet or more, with one implementation using a RP screen  114  that is 35 feet by 7 feet. The projection assembly  120  includes a projector  122  and XY mirror assembly  124  that function together to be able to provide a projection area/field at nearly any location on the RP screen  114  as shown with arrows  126 ,  128  that illustrate a full range in the horizontal direction or along an X-axis range and with arrows  230 ,  232  that illustrate a full range in the vertical direction or along a Y-axis. As discussed earlier, the projector  122  acts to project an animated character or image (such as a character in an animated or live action film) and the XY mirror assembly acts to project this animated character or image within a projection area/field with its center movable along a path or pattern over a plurality of X-Y coordinates on the RP screen  114 . For example, a computer graphic or video of a live fish/mermaid may be projected or output by the projector  122  through air  216  onto the surface of the RP screen  114  and the XY mirror assembly  124  may be operated to cause it to swim in a desired pattern/path on the RP screen  114  such as to swim up to and away from a porthole/window  220  in the submarine  105 , e.g., by moving a single XY mirror or a paired X-mirror and Y-mirror to project (as shown with arrows  126 ,  128 ,  230 ,  232 ) a projection area/field that can be smoothly moved in the pattern/path. Hence, the assembly  120  may be thought of as animating or moving a projection area in a pattern on a projection surface such as an RP or other screen  114 , and this allows high resolution to be achieved with a single projector  122  while allowing a wide range of movement of the image/character across the display surface (e.g., the character animation is not just within the projection area but is provided with movement of the projection area by XY mirror assembly  124 ). 
     The projection assembly  120  may include a processor or CPU  130  that controls operation of the projector  122  and XY mirror assembly  124 . Such control may include operating power sources  132  for the projector  122  and/or motors used to rotate mirrors within the mirror assembly  122 . The processor  130  may also control feeding of images/frames  144  from memory  140  (or other media input source such as a wired or wireless feed to assembly  120 ) to projector  122 . For example, the projector  122  may be operated by the processor  130  manually via an operator using one or more I/O devices  136  to activate the projector  122  (such as a mouse, a voice control program, a keyboard, a touch screen, or other I/O device) or a show program or module  138  may be run by the processor  130  and ride input  139 , such as a vehicle position sensor indicating that the ride vehicle  105  is approaching or is proximate to the window  112  and RP screen  114 , may be processed to determine when the processor  130  should activate the projector  122  or feed it image input  144 . The media  142  is labeled as “predistorted” as it may be useful in some applications to account for keystone distortion that may occur as the projection area is moved away from a position orthogonal from the assembly  124  to locations on the RP screen  114  that may be at relatively large angles (e.g., that may cause the shape of the projection area and a contained image to change in shape and/or size without such predistortion, with one correction method discussed below). 
     The control of the XY mirror assembly  124  may be accomplished with a motor controller  134  that operates, in one embodiment, a first motor to pivot an X-axis mirror about a shaft or center axis and a second motor to pivot a Y-axis mirror about a shaft or center axis. The motor controller  134  generally operates to cause these motors to position the mirrors so as to project the character or image within a projection area/field with X-Y coordinates of its center of rotation or center point being selected based upon a source media-driven projection pattern  145 . This pattern  145  is taken from or derived from character or image positions within a source media (such as an animated film or live action movie intended for projection upon full size display surface such as the RP screen by a single, still projector). These character positions from the source media are used to generate a set of X-mirror positions (or its trajectory)  146  and a set of Y-mirror positions (or its trajectory)  148  that are stored in memory  140  and used by the motor controller  134  to drive mirror motors to properly position the X mirror and the Y mirror with the mirrors being independently operated but their movement synchronized to achieve a fluid movement of the projection area/field along the defined pattern  145 . 
       FIG. 3  illustrates a projection system  300  that may be used to create a display or visual effect according to an embodiment of the invention. As shown, the system  300  includes a projection surface  306  such as an RP or other type of projection screen or simply a wall, floor, ceiling, or other surface. A moving mirror projection assembly  302  is provided and positioned to project on the surface  306  (which may be nearby or relatively far away such as up to about 20 feet or more away), and the projection assembly  302  may contain components as shown in  FIGS. 1 and 2  (or as shown in  FIGS. 5-8  below) to project or output images  304  that are projected onto the surface  306  in projection areas/fields (e.g., with a particular shape and size) that are each typically a subset or fraction of the area or size of surface  306 . 
     Significantly, the projection assembly  302  is adapted to cause the projected images to move such that the X-Y coordinates of the projection area/field follow a predefined pattern or a pattern/path that is defined in real time or “on the fly” (e.g., in response to some input stimuli or data such as a position sensor that the assembly  304  reacts to so as to position the projection area relative to a moving object). Other portions of the surface  306  are non-projection areas or background portions  308  that may, if desired for an application, be maintained black or non-illuminated because the projection assembly  302  only projects upon a projection area (e.g., all or substantially all of the light  304  output from the projector of the assembly  302  is contained within or directed into the projection area  310 ,  320 ,  330 ,  340  by the positioning reflectors or mirrors). 
     The pattern shown in  FIG. 3  is overly simplified for clarity sake. As shown, a projection area  310  is generated by the projection assembly  302  at a first time such as at the start of a pattern or trajectory of the character or image for a show/effect. The projection area  310  in this example is circular in shape and may be several inches to several feet (or more) in diameter, with one embodiment using a diameter of about 18 inches. In other cases, other shapes are used such as to suit a particular character/image shape and can be set or adjusted through the use of an aperture or stop in the projection assembly (e.g., upstream or downstream of the mirrors or the like). Again, the size of the projection area  310  is typically a small fraction of the surface  306  so as to concentrate the output light and resolution of the projector of assembly  302  on just a portion of the surface  306  (e.g., to allow the image  312  to be viewed from a short distance without loss of resolution and/or to increase the brightness/sharpness/color of the image  312 ). An animated character or image  312  is displayed within the projection area/field  310 , and the character  312  is “animated” in the sense that it is a projection of numerous frames per second (such 24 to 30 or more) and typically will be changing between at least some of these frames to be animated or in motion within the projection area/field  310 . In some applications, just the image  312  is projected in the area  310  while in others background or additional images may be included in the projected images  304  and shown in area  310  while in other cases more than one character or image  312  is included (e.g., “character” or “image” here is intended to include one or more objects or characters that can be animated in area  310 ). 
     The projection or projected area  310  is positioned at a first position in a path or pattern with its center or center of rotation  314  at a particular X-Y coordinate (e.g., a center of the surface  306  or some other location). The character or image  312  is animated in a second or additional manner by operating the projection assembly  302  to move the projection area to a second position as shown with arrow  316  (moving the same projection area to a new position or creating a second projection area  320  with its center  324  having differing X-Y coordinates from  314 ). As discussed below, the movement  316  is smoothly accomplished and the movement  316  is chosen based upon a source media to provide a desired projection or animation path or pattern (e.g., the movement  316  may be tied to or correlate to the animation within the areas  310 ,  320  such as by moving very little when the animation of the character indicates the character is stationary and then moving to the left (or other direction) at a speed indicated by the animation of that character within the areas  310 ,  320  such as swimming quickly or slowly to the left or other direction “causing” or being linked to movement  316 ). 
     The movement  316  is continuous due to the characteristic of the projection assembly  302  that it continues to project images  304  even while the movement is occurring such that in practice there would not be separate projection areas as shown for ease of illustration but instead the projection area  310  would simply appear to move  316  to where area  320  is shown. Such movement may be very quick or may take several seconds and, as such, the projection area  310  may be produced by displaying one to many frames of the source image during the move. In other words, the image/character  312  may be animated in a manner that coincides with the movement  316  to the new location/projection area  320  (such as a fish animated to be swimming in a particular direction, a bird flying in that direction, a person walking in that direction, and so on), and, in such a manner, the movement  316  may be tied to or linked to the animation or changes of the image  312  displayed within the projection area  310 . 
     The pattern or X-Y positions used by the projection assembly  302  to position the mirrors may cause the projection area  320  with displayed image  322  to move  326  to a new position or to provide a third projection area  330  with its displayed image  332  in a new X-Y coordinate position as defined by the center of rotation  334 . Further, the pattern may then require the projection area  330  to be moved  336  to another or fourth position as shown with projection area  340  having its image/character  342  displayed in a differing X-Y coordinate position as determined in part by the location of its center  344 . Again, these movements  316 ,  326 ,  336  define a pattern or trajectory of the projection area (and its contained image/character) on the surface  306  and the movement typically is not abrupt but instead smooth or continuous, which may have been better depicted in the system  300  with numerous projection areas that overlap with each other that follow the pattern defined by the path or arrows of  316 ,  326 ,  336 . In practice, each frame of the image  304  output by the projection assembly  302  typically will have an X-Y coordinate associated with it such that the mirrors of assembly  302  may be moved or have their position set for each frame (e.g., 24 to 30 mirror positions for both the X and Y mirrors although movement is not required such as when it is desirable to keep the image  312  stationary for a period of time or number of frames such as near a porthole of ride  100  for a period of time while a character  312  “talks” to the audience). 
       FIG. 4  illustrates another display or projection system  400  in which a pair of moving mirror projector assemblies  402 ,  403  is provided to create an effect where images within two projection areas/fields may interact and move independently about a projection surface. As shown, the system  400  includes a display surface  406  with a background or non-projection area or portion  408  (e.g., black areas framing projected images). The first projection assembly  402  projects or outputs a first set of images  404  and the second projection assembly  403  projects or outputs a second set of image  405  onto the display or projection surface  406  (e.g., an RP screen or the like). The first projection assembly  402  may be operated to provide a first animated image (using a first set of input images/media) that is caused to travel over a first pattern or trajectory while the second projection assembly  403  may be operated concurrently (or separately) to provide a second animated image (using a second set of input images/media) that is caused to travel over a second pattern or trajectory on the display surface  406 . 
     As shown, the first projection assembly  402  may generate a projection area  410  in a first X-Y location while the second projection assembly  403  may generate concurrently (or at an earlier or later time) a projection area  411  in a second, different X-Y location. As shown, the projection areas  410 ,  411  include differing characters/images  412 ,  413  (hut they could include similar ones) and have like shapes such as square projection areas that are a fraction of the size of the surface  406  (such as 1 to 2 feet on a side with the surface being up to 40 feet or more on a side and other shapes may be used and the shapes may differ to create a particularly desired effect). Again, the characters/images  412 ,  413  typically would be animated or in motion within the projection areas  410 ,  411 , and secondary or additional motion/animation is provided by moving the projection areas  412 ,  413  as shown at  416 ,  417  to provide second projection areas  420 ,  421  (or new positions for the projection areas  410 ,  411  as discussed above) with images/characters  422 ,  423  having new (and typically different or spaced-apart) X-Y-coordinates. The movements  416 ,  417  may be concurrent (or partially concurrent) or serial with one performed before the other. These movements  416 ,  417  create a projection or animation pattern for the characters (and/or the associated projection areas). This pattern continues with further movement  426 ,  426  to new X-Y coordinates for projection areas  430 ,  431  and the images  432 ,  433 , with this position being chosen to cause the images  432 ,  433  to be proximate to each other and allow interaction (such as to have to images approach each other to converse, play, or the like). Additional projection assemblies may be provided to allow additional character/images to interact or simply to provide a display with multiple animated character and/or objects with the projection patterns/paths chosen to achieve a desired effect or to comply with a single or multiple source media (e.g., to provide paths/trajectories of images that correspond to the movement of the image in the source media for example if it were projected onto a large surface/screen with a single, stationary projector). 
       FIGS. 5 and 6  illustrate in more detail one embodiment of a moving mirror projection assembly  500  (such as may be used in the system  100  of  FIGS. 1 and 2  or systems  300  and  400  of  FIGS. 3 and 4 ). As shown, a projector  510  is arranged with its output or output lens  512  inserted into or adjacent an end wall  522  of a mirror housing  520  such that its output images (or transmitted or projected light)  514  enters the housing  520  and passes through an interior support structure or wall  524 . The projector  510  may take many forms to practice the invention and generally may be any device that can be used to display images upon a display screen or surface such as readily available film/movie or digital video projectors. The assembly  500  is often used to project onto a relatively small projection area on a nearby screen/surface, and, as a result, a less expensive, low output projector may be used for projector  510  (but other embodiments may use more expensive, high output projectors), e.g., the light is concentrated upon a small, nearby area such as a circle with a diameter of 18 inches or so on a projection screen or surface rather than dispersed across an entire surface. In one embodiment, the projector  510  used is a 5000 ANSI lumens, 1024×768 resolution projection such as available from Panasonic Corporation of North America (e.g., the Panasonic 5600 or similar model) but, of course, the invention may be practiced using other projectors with differing resolutions and/or outputs. 
     The images from the projector  514  travel within the housing  520  until they strike the surface of a first mirror  532 , which may be an X-axis mirror (or Y-axis in some embodiments). Prior to striking the mirror surface, the light  514  may be sized/shaped by passing it through a stop or aperture  530 . For example, it may be desirable to provide a circular, oval, rectangular, square, triangular, or other shape for the projection area, and the hole or opening in the stop may be selected to provide such a shape. Further, the stop  530  may be used to trim or block excess or unneeded light from the image  514  such that the majority or a large portion of the light that strikes the mirror  532  corresponds to the image or character to be projected on a surface by the assembly  500 , with the size and shape of the opening in the stop  530  being chosen and tailored to suit the particular character or characters in the projector output  514  and distance from the stop  530 , which is defined in part by the length, L 1 , from the projector output  512  to the interior support wall  524 . The aperture  530  acts to soften the black edge of the projection, blending the video black into the true black where nothing is being projected while also hiding the hard rectangular edge of the projector output. 
     The X-axis mirror  532  is pivotally supported on the sidewalls of the housing  520  and is moved about its center axis by motor  610  as shown by second position  533  and arrow  536 . For example, a shaft or pin  534  may extend from a first end where it is attached or linked to a drive motor (or X-axis motor)  610  to a second end where it is pivotally attached/supported by a sidewall of the housing  520 . The motor  610  operates in response to X coordinates or positions received at a motor controller (not shown) and rotates the shaft/pin  534  to rotate  536  the mirror to various positions as shown at  532 ,  533  to cause the reflected images  538  to have a desired X coordinate or horizontal position. 
     The reflected images  538  then travel in housing  520  toward the surface of a second mirror or Y-axis mirror  540  that is pivotally mounted in the housing  520  to move or rotate  616  generally about its central axis as shown with second Y-axis mirror position  618 . The Y-axis mirror  540  is also supported by a shaft or pin  542  that is attached or linked at one end to a drive or Y-axis motor  544  and at a second end it is pivotally attached to the inner support wall or structure  524  of housing  520 . The two mirrors  532 ,  540  are spaced apart to allow free rotation about the support pins/shafts  534 ,  542  and are arranged such that the rotation of the Y-axis mirror  540  defines or sets the vertical position or Y-axis coordinate of the projected image (or center of rotation of the projection area). This is achieved in part by having the support pins/shafts  534 ,  542  extend orthogonal to each other in spaced apart, parallel planes. The mirrors  532 ,  540  may take many forms to practice the invention with the illustrated embodiment having the first or X-axis mirror  532  be rectangular in shape and smaller than the Y-axis mirror  540  (such as a rectangle that is about 2 to 6 inches in width and 4 to 10 inches in length with it being understood that the size and shape of the mirror  532  is not limiting to the invention). The rotation of the X-axis mirror  532  generally is limited first to a range that causes the image  538  to always strike the Y-axis mirror  540  and also to suit the display surface (e.g., will be limited to keep horizontal or X-axis travel of a projected image/character upon a display surface). The Y-axis mirror  540  is shown to be generally rectangular in shape, also, and may be about 3 to 6 inches in width and 8 to 16 inches in length; again, the shape and size is chosen in part based on the projection surface/screen and the amount of rotation of shaft  542  is chosen such that the reflective surface can be contacted by reflected images  538  and also to limit travel of a projected image  620  to a vertical or Y-axis travel that suits the projection surface/screen&#39;s size and/or shape. 
     The motors  544 ,  610  may take many forms to practice the invention and may be high precision DC servo motors or the like (e.g., typically not stepping motors but instead servo motors or similar motors that may be useful for X-Y tables, machine tooling/factory automation, and other applications where carefully controlled bi-directional positioning/rotating of a shaft is desired) so as to provide rapid and smooth movement/rotation of the attached shafts  534 ,  542 . For example, servo motors with encoder counts of over 150000 counts may be used such as ones with 180000 count encoders or the like so as to provide fluid movement of the two mirrors  532 ,  540  and of the projected characters/images as the projection area/field is moved along an animation pattern. Some applications of the motors  544 ,  610  are able to provide numerous position changes per second such as up to 60 positions or more per second (e.g., to allow one or more than one position move per frame of the projected video/film or the like). Note, the motor chosen may limit the size of a movement of a projected area per unit time and in other cases the animation effect dictates a slower than maximum speed motor capacity projection area movement/animation so as to more closely match a realistic or desired motion of the character or object being animated (e.g., movement of projection area may be set to substantially match a speed of movement such as running, swimming, flying, falling, or the like of the image/character). 
     From the embodiment of projection assembly  500 , those skilled in the art will readily understand that numerous arrangements of mirrors, stops/apertures, image outlets, and XY mirror configurations and positioning may be used to provide the function of projecting an image/output of a projector onto a projection area/field that can have its X-Y coordinates chosen to match an input pattern/trajectory. Also, the discussion of X-Y coordinates can readily be expanded or interpolated to nearly any useful coordinate system and the inventive aspects described are not limited to a planar screen. For example, the projection systems of the invention may be used with a dome shaped projection surface such as those used in planetariums and the like (e.g., to display a space station, a space craft, a shooting star, or the like on a spherical screen). In other cases, the display surface may include more than one screen and such multi-screen or display surface implementations may include screens in differing planes and some of these planes may be non-parallel relative to each other and may even be transverse or orthogonal to each other (e.g., the coordinates for the mirror projector assembly may be multi-dimensional). 
     For example, space or other restraints may require that the housing  520  be more compact.  FIG. 7  illustrates a moving mirror projection assembly  700  with components similar to that shown in  FIG. 5  for assembly  500  but having a more compact (less long) housing  520 . As shown, the length of the housing  520  is reduced by shortening the distance between the wall  522  to which the projector  510  is attached or mated and the interior support or structure wall  524  (e.g., L 2  is less than L 1 ). This is achieved in this example by the inclusion of a pair of folding or redirecting mirrors  710  whose output  714  is then directed to through aperture  530  and onto the first or X-axis mirror  532 . Other arrangements may also be used to provide a desired flow of the projector output image  514  or  714  to the X-axis mirror  532 , but the one shown is useful for providing a reduction in length of the housing of up to about 40 percent. 
     In practice, the actual movement of the mirrors demands relatively high precision and repeatability from the motors (e.g., the X-axis motor and the Y-axis motor) as well as from feedback devices and other control components (which may all be grouped into or labeled a motor controller for purposes of this description) so as to produce image motion on a display surface or screen that is smooth and tightly controlled (e.g., so that the movement of the projection area/field in which a character or object image is displayed is smooth or not jittery and is precise along a particular animation pattern or trajectory). In one embodiment, this is achieved by providing a mirror control assembly  800  that includes a mirror axis controller  820  that receives as input desired trajectory or positioning data  810  (such as from a processor or show control program) and outputs signals to operate a DC servo motor  832  so as to rotate/position a movable mirror surface  834  (note, other motors may be used in some applications such as high end step motors or non-servo-type motors). 
     The mirror axis controller  820  may be provided using a variety of circuit components and configurations and generally includes several functional and/or signal processing components including an arc tangent compensation module  822 , a position loop  824 , a velocity loop  826 , a digital to-analog converter  828 , and an amplifier  830  (e.g., to close the current loop) that is connected to the motor  832 . Note, one controller  820  is shown and, typically, a similar controller would be provided for each mirror or each mirror axis. To enhance precision and repeatability, the controller  820  further includes a feedback loop with an encoder  836 , a high-resolution interpolation module  838 , and an integrator or integration module  840 . The encoder  836  may be a high resolution encoder to allow the system  800  to resolve small movements of the motor  832  and attached/driven mirror surface  834  such as movements as small as 10 arc seconds, with one arc second being 1/3600 th  of a degree. 
     In addition to the high degree of spatial resolution provided by controller  820 , the desired trajectories  810  (e.g., based on 30 frames/second animation data may be interpolated by the controller  820  at a high rate (e.g., over about 2 KHz) to allow more precise and smooth motion of the mirror surface  834  (and resulting or produced character or object in a projection area/field on a display surface), when compared to the static projection of 30 or 60 discreet video frames per second. The components of the controller  820  may be implemented using various forms of hardware (e.g., custom or off the shelf ICs and the like), firmware, and software or combinations thereof (e.g., one or more of the hardware devices shown in  FIG. 8  may be replaced completely or in part with software devices). 
     The moving mirror display or projection systems described herein were created with two main design goals in mind. First, the systems can be used to faithfully recreate character motion from an original animation or other source media with a set of moving mirrors (e.g., to move the character in its projection area across a larger display area as if projected with a fixed or non-moving projector over the entire surface using the source media). The moving mirror assemblies are adapted to allow all the resolution and brightness of an inexpensive or other projector to be concentrated where it is needed, i.e., on the character or object in the projection area. No pixels are wasted on areas of the screen or display surface where nothing is being shown. Since no light is sent to these other areas, the black areas of the scene maintain complete darkness. Second, the moving mirror system creates a realistic, smooth character motion along the animation or projection pathway or pattern that is not achievable with other projection systems including a single static projector (e.g., the use of mirrors moved with high precision DC servo motors provides smoother motion/animation of a character based on its position data from the original or source media than animation within that source media). 
     It may be useful at this point to discuss in more detail an implementation of a projection system of the invention similar to that shown in  FIGS. 1 and 2  (e.g., for a submarine ride), design challenges, and useful solutions generated or used by the inventors. One design criteria for the ride system and associated projection/display assembly was to project an animated character that appears just outside of the viewer&#39;s submarine porthole while also maintaining realistic detail of the character within a dark environment (e.g., to simulate undersea conditions). In this application, each projection area (e.g., RP projection screen) was approximately 35 feet long and 7 feet high while the character was to be about 18 inches long (e.g., an animated fish), with 3 such areas or screens used to service a show portion of the ride system. Viewers were spaced apart from the screen by about 4 feet. Existing projection systems typically would have provided stationary projectors blended to cover the total area, but the result is low-resolution characters or objects with unacceptable black levels (e.g., the non-projected areas appear gray or even lighter) and high media production costs. In some cases, many projectors are required to cover the area and each would have a dedicated playback device. 
     Another design criterion was to create projected animated fish that could interact and come into “contact” with a mechanical feature (e.g., a mechanically animated jellyfish for example). In this display embodiment/application, a screen is suspended just over the mechanical/physical feature (e.g., over/adjacent and proximate to the jellyfish to allow the projected image/character to be shown near the physical feature). In this embodiment, prior projection techniques were not useful as they produced unacceptable black or background levels of light that displayed or revealed the screen, which ruined the effect of a real structure interacting with an animated character or image. In contrast, the use of a moving mirror projector assembly with the strategically positioned display surface or screen allows the character to be displayed with animation and with a truly black background about the projected image (e.g., no light is projected outside the projection area/field). 
     For an embodiment with a 35 foot by 7 foot projection surface, a desired resolution of about 800 pixels to show or display an 18-inch character equates to an effective resolution of 18,667 by 3733 pixels. Tiling 90 projectors and having 90 synchronized HD playback devices may be used in some cases to address the resolution problem, but this would be expensive and complicated and most of the projectors would be projecting nothing (but a small amount of light that makes the non-projected areas gray) except for the brief moments when a character passes through a specific projection field/area corresponding to the projector. In contrast, a moving mirror projection system may include a projector assembly (as described above) for each character in a scene (such as  1  as shown in  FIG. 3 ,  2  as shown in  FIG. 4 , or  3  or more as needed to provide the number of characters desired for a scene/show). The moving mirror projection assembly functions to concentrate all of their resolution (e.g., 1024 by 768 pixels or the like) wherever the character travels about the projection surface (e.g., across or along its projection or animation path/pattern) by moving the paired XY mirrors (or through the use of a single XY mirror in some applications). Hence, the moving mirror projection systems of the invention are able to achieve enhanced resolution within the projection area. 
     Improved brightness is also achieved with use of the moving mirror projector assemblies. By concentrating the light from a large format projector (or other projector/display device) into a smaller space (e.g., a relatively small projection area/field) by use of long focal length lens (or the like), the light associated with a character/image is also concentrated, thereby creating a proportionally brighter image. For example, if a projector is used to project over an entire projection surface the brightness of the character will have a first value but when the same projector is used to project onto a projection area that is ⅛ to 1/50 (or a smaller fraction) of the surface the brightness is increased by 8 to 50 times (or more). The moving mirror projection systems allow the use of less expensive, low output projectors to achieve significantly improved character brightness even when compared with high output, large format projectors if these projectors are forced to cover the entire projection surface. Super dark blacks are also achieved with use of the moving mirror projector assemblies. The moving mirror projector assembly only sends light where it is needed to display a character (e.g., a projection area containing the character&#39;s image), and in this manner, no light is being sent by the projector anywhere, which results in complete blackness in non-projected areas. 
     Another benefit that has been achieved or identified in the projection systems described has been smooth motion of the character when the projection areas are moved along the animation or projection patterns or trajectories. The moving mirror system is able to achieve smooth, ultra-realistic motion that is generally not possible to achieve with non-moving projectors. Standard projection systems rely on the changes in position between different frames of media to create perceived motion such as 30 frames per second or 60 fields for video and 24 frames per second for film. The moving mirror projector assemblies create continuous motion with no motion artifacts or “stuttering” of the image. Combined with high resolution and brightness, the smooth motion provided by the moving mirrors creates a hyper-realistic quality to the animated characters that would otherwise not be possible or practical. 
     However, one challenge that may occur with the use of moving mirrors to create character motion/animation is motion distortion correction. In some embodiments, it may be useful to provide corrected, near-rectilinear motions on the projection surface/screen. The motion of the mirrors may be modified based on the geometry of ray traces reflecting off a rotating mirror surface. The graph  900  of  FIG. 9  is useful for making such corrections of rays reflecting off a surface. Correction can be determined by determining θ 2  given or knowing L 1 , θ 1 , and X using the following:
 
tan(θ 1 +θ 2 )=( L   1   +Y )/ X  
 
θ 1 +θ 2 =tan −1 (( L   1   +Y )/ X )
 
θ 2 =tan −1 (( L   1   +Y )/ X )−θ 1  
 
θ 2 =tan −1 (( L   1   +Y )/ X )−tan −1 ( Y )/ X )
 
     Bouncing the projector output or beam off two mirrors compounds this problem as the distance that the principle ray travels increases with increasing deflection of the first (or X-axis) mirror. Thus, the non-linearities of the second (Y-axis) mirror are different depending on the position of the X-axis mirror. This correction of the mirror trajectories is done in some embodiments both in a pre-processing step for the position data from the source media and in an interpolation step at run time in the motion or mirror motor controller(s). A graphical user interface or other device may be used to allow users to make in-the-field or additional modifications to the distortion corrections (pre-processing step) and obtain immediate results/feedback on their modifications by running the position data with the moving mirror projection assembly in a particular projection set up or environment. This allows a user or operator to perform fine tuning of the motion distortions/corrections to suit the particular requirements of any given projection geometry and other limitations. 
     Without additional corrections of the media that is projected or provided to the projector, there may be image distortion (e.g., keystone, rotation, and scale distortion of the image or the like), and some embodiments of the invention provide correction for such image keystone, rotation, and scale distortion as a pre-processing step. In use of the projector assembly to display a character across a larger display surface with a single projector, the moving mirrors move (or the projected character moves) farther from the center of the projection surface, and vertical and/or horizontal keystone distortion may be introduced into the image. Due to the varying installation parameters of each projector, folding mirrors (or no folding mirrors), and display surface/screen, each projection system may experience unique or differing distortion. The distortion may be corrected in some embodiments by driving the projector live from a laptop or other computer/controller device, then manually changing the position of the mirrors to the extents of the character motion. For each position, an opposite distortion may be created by introducing a keystone distortion that cancels out the true or expected distortion, which results in a rectilinear and scaled output image for the projection assemblies of at least some embodiments of the present invention. For example, input position numbers (from the source media) may be processed through this “distortion field.” Then, a correct “pre-distortion” may be applied to the source media to create a “pre-distorted” media that may be input to or played by the projector so that when the scene is played the character (e.g., an animated fish or the like) remains the same or correct size and shows no (or substantially no) keystone distortion regardless of where the character travels across the display or projection surface (e.g., even when at a large angle relative to perpendicular from the mirror assembly outlet). 
     Video black near a character may be hard to avoid in the area between a character and the edge of the moving projection area/field provided by moving mirror assemblies. As described with reference to  FIG. 5-7 , an aperture may be included in the mirror housing such as at the point in the beam from the projector where the aperture/stop can be used to soften the edge of the video (and shape the output projection area/field). The aperture may be used to hide the hard edge of the video frame and blend the complete black provided by the projection assembly about the periphery of the projection field and the bright character in the center. The resulting “glow” around the character may be desirable in some applications such as to mimic diffuse underwater lighting effects (e.g., that may be used in underwater filming or computer graphic-based media sources). 
     Although the invention has been described and illustrated with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example, and that numerous changes in the combination and arrangement of parts can be resorted to by those skilled in the art without departing from the spirit and scope of the invention, as hereinafter claimed. The term “mirror” as used in this description is intended to describe conventional mirrors and mirrored surfaces but also other reflectors and reflective surfaces and materials useful for reflecting or redirecting light, and the mirrors shown are generally planar but other cross-sectional shapes may be used such as concave, convex, parabolic, and other mirror configurations. 
     Also, a one-projector assembly display or projection system was discussed in detail with a second embodiment shown with two projectors to provide two characters that may interact. The number of projectors is not limiting to the invention with some embodiments including a plurality of projectors such as one per character/object to be displayed on a corresponding display surface(s). In other embodiments, two or more projection assemblies are used to display the same or differing characters/objects along a long or large projection surface with each assembly projecting on a subset of the projection surface (which may be made up of a number of separate FP or RP screens or other surfaces) such as for providing displayed images along an amusement or theme park ride. 
     Additionally, the input imagery or streams provided to the projectors may be pre-recorded or computer-generated in real time as may be the animation or projection patterns/paths used to define the X-Y coordinates of the centers of projection areas/fields. In some applications, the size or amount of travel of the character as provided by the moving mirrors may be adjusted in the field with software or other tools such that the travel pattern fits a particular projection surface/screen. Preferably this field adjustment of the amount of travel can be done without having to modify the input media or distorting the output characters. For example, field adjustments/control can be used to align projected characters with fixed objects (e.g., a mechanically animated character that the projected character or object interacts with such as landing on it, brushing or contacting it, or the like) while avoiding edges of projection screens, folding mirrors, and/or structural supports. 
     In some embodiments, the projection or animation pattern (e.g., X and Y coordinates or positions) may not be predefined (stored in memory). Instead, it may be useful for the projected character to follow a path or pattern defined all or in part based on real time data. For example, real time tracking may be performed to determine a location of a projection area displaying an animated character/object (e.g., a position sensor placed on or held by a live actor or the like), and positioning of the sharp/bright media of the moving mirror projector assembly in a live show or in an interactive video or similar game. In some embodiments, the brightness of the projected character may be used in higher light applications/environments such as ambient light or outdoor projection surfaces. For example, concentrated small characters or objects may be projected in a bright, ambient light environment such as the side of a building or on the ground in a pedestrian area. 
     In another embodiment of a projection system, a moving mirror projector assembly is used to provide characters that are able to move off of a movie or similar large fully projected screen onto other surfaces within the theater. For example, a character in a movie may move off of the main screen to a side wall, the floor, or the ceiling (or any other projection/display surface) through the use of a moving mirror projector assembly and a properly designed projection/animation path or pattern provided to the mirror motor controller(s). This may be achieved by providing an KY projection assembly to serve each adjoining service (e.g., an assembly for the ceiling next to a conventional projector screen, another assembly for a sidewall, and so on). In other cases, it may be desirable to provide a 3D effect or Z-axis effect such as when multiple projection surfaces at differing distances from the projection assembly outlet are utilized. A Z-axis effect may be achieved in embodiments of the invention by incorporating a motorized zoom lens or similar device and/or a motorized iris as the aperture. 
     While the projection areas described herein are typically a single or fixed size and shape, there may be applications or embodiments where it is useful to increase or decrease the size of the projection area (or alter its shape such as to suit differing characters or achieve a particular effect). For example, a character may move further away from the audience or closer to the audience within the projection area (e.g., grow smaller or larger within the media fed to the projector). In such cases, it may be desirable to allow the projection area to vary in size such as to avoid situations where there is too much “gray” area about the character when it is smaller than the projection area and where the character completely fills or exceeds the projection area. In such cases, the block or aperture may of the assembly may be configured to have a variable size (and/or shape) that is controllable based on triggers in the projector input media or other devices (such as by a projector controller processor and/or ride or assembly control module or the like). A character&#39;s pose might dictate a dynamic change in aperture, as in a fish viewed from head on versus a fish in profile or the change in size as a fish swims away or toward a viewer.