Abstract:
An example embodiment of the present invention may include an apparatus that captures 3D images having a lens barrel, including a lens disposed at a first end of the lens barrel, an image capture element at the second end of the lens barrel, and a refracting lens positioned along the optical axis of the lens barrel. The image capture device may have an adjustable active region, the adjustable active region being a region capable of capturing an image that is smaller than the total image capture area of the image capture element. The image capture element may capture images continuously at a predetermined frame rate. The image capture element may change the adjustable active region and the set of positioning elements may be adapted to continuous change the position of the refracting lens among a series of predetermined positions at a rate corresponding to the predetermined frame rate.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. provisional application Ser. No. 61/194,297 filed on Sep. 25, 2008. This application is related to U.S. non-provisional application Ser. No. 12/320,309 titled “Single Camera Device and Method for 3D Video Imaging Using Refracting Lens Array” filed on Jan. 23, 2009 the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to three-dimensional (3D) imaging and more particularly to a device and method for capturing 3D images and video using a camera having a lens, refracting lens, and an image capture device having an adjustable active area. 
     2. Description of the Related Art 
     Non-contact three-dimensional cameras, or digitizers, generally fall into four categories: stereoscopic digitizers, silhouette digitizers, timing digitizers, and projected pattern digitizers. 
     Stereoscopic digitizers traditionally employ multiple two-dimensional (2D) cameras to produce multiple viewing angles to capture multiple images of the target object from different angles. A 2D camera is positioned at a known offset relative to other 2D cameras. Given the positions of each camera it is possible to provide a correlation algorithm the necessary variables to identify the three-dimensional location of objects in the images. 
     Stereoscopic digitizers attempt to mimic the visual and mental facilities of the eyes and brain to identify the location of object surfaces in 3D space. The eyes  20  and brain  25  work in conjunction to obtain a three-dimensional mental model of the target object  5  ( FIG. 1 ). Each eye  20  captures its own view ( 10   a  and  10   b ) and the two separate images are processed by the brain  25 . Each eye  20  has a slightly different placement, resulting in a different point of view and field of view  10   a  (left) and  10   b  (right) of the target object  5 . As a result, each eye obtains a slightly different left image  15   a  and right image  15   b  of the target object  5 . When the two images  15   a  and  15   b  arrive simultaneously in the back of the brain, they are united into one model, by matching up the similarities and adding in the small differences. Using the two images,  15   a  and  15   b , the brain compares the right image  15   a  and left image  15   b  to identify the number and magnitude of the similarities between the images to correlate the relationship between the images. Using the correlation between the images, the brain creates a 3D model of the target object  5 . 
     A minimum requirement for stereoscopic digitizers is the ability to obtain two images from two different points of view.  FIG. 2  illustrates a conventional 3D stereoscopic camera setup. Conventionally, obtaining the minimum two images is done with two distinct 2D cameras setups  50   a  and  50   b , each positioned at a pre-defined distance from one another. Each 2D camera setup  50  includes an image pickup device, such as a CCD  30  and lens  35  positioned along an optical axis  40 . Each camera  50  is positioned to point to the same target object  45 . 
     By using an algorithm to identify the similar surfaces in the image obtained from camera  50   a  and camera  50   b , and given the pre-defined distance between the cameras  50 , the algorithm computes the three-dimensional location of the surface of target object  45 . 
     One problem with stereoscopic digitizers is that they are generally both bulky and expensive because they require the use of multiple 2D cameras. Furthermore, the performance of the 3D camera setup is dependent on the careful configuration and alignment of the 2D cameras. Any change in the distance between the cameras or the angle between the cameras can pose problems to the pattern recognition algorithm, forcing the re-calibration of the hardware and software for the changed positions. 
     SUMMARY OF THE INVENTION 
     The present invention provides SINGLE CAMERA DEVICE AND METHOD FOR 3D VIDEO IMAGING USING REFRACTING LENS. 
     An example embodiment of the present invention may include an apparatus that captures 3D images having a lens barrel. The lens barrel may include a lens disposed at a first end of the lens barrel, an image capture element at the second end of the lens barrel, and a refracting lens positioned along the optical axis of the lens barrel. The image capture device may have an adjustable active region, the adjustable active region being a region capable of capturing an image that is smaller than the total image capture area of the image capture element. The refracting lens may be mounted to a set of adjusting elements which may adjust the position of the edge of the refracting lens. The set of positioning elements may be configured to position the refracting lens such that light entering the lens barrel at a first angle, relative to the optical axis, is refracted to the adjustable active region at a first location on the image capture element. The image capture element may be configured to capture images continuously at a predetermined frame rate. Furthermore, the image capture element may change the location of the adjustable active region and the set of positioning elements may be adapted to continuous change the position of the refracting lens among a series of predetermined positions at a rate corresponding to the predetermined frame rate. 
     Another example embodiment of the present invention may include a method for capturing 3D images. The method may include passing light through a lens at a first end of a lens barrel, capturing the light at an adjustable active region of an image capture element at a second end of the lens barrel, positioning a refracting lens positioned along an optical axis of the lens barrel; the refracting lens being mounted to a set of positioning elements. The method may also include positioning the refracting lens such that light entering the lens barrel at a first angle, relative to the optical axis, is refracted by the refracting lens to the adjustable active region at a first location on the image capture element. The capturing step may include capturing images continuously at a predefined frame rate. Furthermore, the method may include continuously changing the position of the refracting lens to different positions from among a series of predetermined positions in a predefined order, and changing the location of the adjustable active region to a location to correlate with each of the series of predetermined positions in a predefined order at a rate corresponding to the frame rate of the imager. 
     The present invention can be embodied in various forms, including digital and non-digital image capturing devices and methods, robotic imaging devices, virtual simulations, and the like. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other more detailed and specific features of the present invention are more fully disclosed in the following specification, reference being had to the accompanying drawings, in which: 
       These and other more detailed and specific features of the present invention are more fully disclosed in the following specification, reference being had to the accompanying drawings, in which: 
         FIG. 1  is a diagram illustrating the basic principles of stereoscopy. 
         FIG. 2  is a diagram illustrating the conventional implementation of a stereoscopic camera. 
         FIG. 3  is a diagram illustrating an example embodiment of the present invention. 
         FIG. 4  is a diagram illustrating an example embodiment of the components of the lens barrel in accordance with the present invention. 
         FIGS. 5A and 5B  illustrate an application of the example embodiment of the components of the lens barrel with respect to distant objects in accordance with the present invention. 
         FIGS. 6A and 6B  illustrate an application of the example embodiment of the components of the lens barrel with respect to near objects in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following description, for purposes of explanation, numerous details are set forth, such as flowcharts and system configurations, in order to provide an understanding of one or more embodiments of the present invention. However, it is and will be apparent to one skilled in the art that these specific details are not required in order to practice the present invention. 
       FIG. 3  is a diagram illustrating an example embodiment of a 3D camera  100  in accordance with the present invention. Camera  100  may receive an image, via a light source, through lens barrel  122 , which includes a lens  102 , a refracting lens  104 , and an imager  106 . 
     Imager  106  may be an image capture device. Imager  106  may have an adjustable active region. The active region may be a sub-region of the entire imaging capture area of the imager  106 . For example, if imager  106  is a CCD, only light information from pixels in the active region will contain readable imaging data. Alternatively, imager  106  may be a common CCD or CMOS, and the active region may be cropped from the image captured by imager  106 , by a component of imager  106  or DSP  110 . Alternatively, imager  106  may be an image pickup medium or a prism that deflects light at the end of the lens barrel  122  to an image pickup medium. Camera  100  may also include a CPU  114  for controlling Application-Specific Integrated Circuit (ASIC)  112 , and thereby control DSP  110  and L/R separator  116 . 
     An image captured by imager  106  may pass to digital signal processor (DSP)  110 , which may convert the image into a digitally storable or transmittable format, such as a bitmap, jpeg, or other format appropriate for analysis. DSP  110  may be a conventional 2D type digital signal processor or a specialized processor for processing image data from imager  106 . For example, DSP  110  may be specialized to identify the active region in the data from imager  106 , and only process information in the active region. 
     Left/right image separator (L/R separator)  116  may de-multiplex the image data output from DSP  110  into two independent outputs which are provided to HDSDI encoders  118   a  and  118   b . The outputs of HDSDI encoders  118   a  and  118   b  pass through an external interface of camera  100  to a recording medium or transmission medium. 
     By properly refracting incoming light using refracting lens  104  onto the active region of imager  106 , camera  100  may capture two distinct images of a target object without using a plurality of lens barrels  122  or moving lens barrel  122 . Camera  100  may quickly capture the two distinct images or record 3D video by operating the various components in a synchronized fashion. To capture 3D images or 3D video, camera  100  may operate imager  106 , DSP  110 , refracting lens controller  108 , and L/R separator  116  at a uniform frequency. For example, imager  106  may operate at a frame rate of 60 frames per second (60 fps). This frame rate is provided to refracting lens controller  108 , DSP  110 , and L/R Separator  116 . Imager  106  may also operate in conjunction with refracting lens controller  108  to identify the optimal placement of refracting lens  104  for the active region associated with each frame. 
     During capture, imager  106  may adjust the location of the active region in synchronization with the frame rate. Refracting lens controller  108  may continually re-align refracting lens  104  with the active region of the imager  106  at a rate corresponding to the frame rate of the imager  106 , e.g., 60 adjustments per second, ensuring that each frame captured by imager  106  represents an alternate image, e.g., a left image and a right image. The output of imager  106  is processed by DSP  110 . The output of the DSP  110  is de-multiplexed by L/R separator  116 , which may use a time de-multiplexing technique or other technique, in synchronization with the refracting lens controller  108  and imager  106  to produce two independent outputs which are encoded by HDSDI encoders  118   a  and  118   b . However, it will be understood that the frame rate may be dictated by the available hardware, particular implementation, and/or situational lighting. 
     While the example embodiment performs stereoscopy using a refracting lens  104  in conjunction with imager  106  to create two points of view, it is equally possible to perform stereoscopy using any number of refracting lenses or any number of viewing angles while remaining within the spirit of the present invention. For example, refracting lens  104  can alternate between 3, 4, or 5 aligned positions to obtain 3, 4, or 5 viewing angles by properly setting the active region of the imager  106 . Refracting lens controller  108  only needs to be capable of aligning the refracting lens  104  to produce a different viewing angle in synchronization with the frame rate and imager  106 . 
       FIG. 4  illustrates an example of a lens barrel  122 , having optical axis  204 , in accordance with the present invention. 
     Lens barrel  122  is directed towards target object  210 . Lens barrel  122  includes lens  102 , refracting lens  104 , imager  106 , and piezoelectric devices  202   a - 202   b , positioned along optical axis  204 . Piezoelectric devices  202   a  and  202   b  adjust the position of refracting lens  104 . 
     Piezoelectric devices  202   a  and  202   b  are controlled by currents and voltages from refracting lens controller  108 . Via piezoelectric devices  202   a  and  202   b , refracting lens controller  108  may change the positions of refracting lens  104  in synchronization with the frame rate of imager  106 . 
     Imager  106  may include a light sensitive surface. Active region  206  represents a sub-region of the light sensitive surface. For example, active region  206  may be a matrix of adjacent pixels on a CCD. Alternatively, the active region may be formed of any combination of pixels on imager  106  that may allow the lens barrel to change the point of view or field of view of the captured image. Alternatively, active region  206  may not represent a region on the imager  206 , but may represent a region of the captured image output by imager  106  that is used for stereoscopic analysis of the resulting data produced by camera  100 . 
     Lens  102  and refracting lens  104  may take many forms, and may be formed of various substances or polymers including, but not limited to, glass, liquids, gels, or plastics. Imager  106  may be or may be used in conjunction with a CCD, CMOS, or any alternative light capturing mechanism. 
     Computing devices such as those discussed herein generally, such as for example, CPU  114 , ASIC  112 , and DSP  110  may each include instructions executable by one or more processors. Computer-executable instructions may be compiled or interpreted from computer programs created using a variety of programming languages and/or technologies known to those skilled in the art, including, without limitation, and either alone or in combination, Java™, C, C++, Assembly, etc. In general, a processor (e.g., a microprocessor) receives instructions, e.g., from a memory, a computer-readable medium, etc., and executes these instructions, thereby performing one or more processes, including one or more of the processes described herein. Such instructions and other data may be stored and transmitted using a variety of known computer-readable media. 
     Similarly the output of imager  106 , DSP  110 , L/R separator  116 , HDSDI  118   a , and HDSDI  118   b  also produce output that may be stored on a computer readable medium or transmitted via a transmission medium. 
     A computer-readable medium includes any medium that participates in providing data (e.g., instructions or images), which may be read by a computer. Such a medium may take many forms, including, but not limited to, non-volatile media, volatile media, and transmission media. Non-volatile media include, for example, optical or magnetic disks and other persistent memory. Volatile media include dynamic random access memory (DRAM), which typically constitutes a main memory. Transmission media include coaxial cables, copper wire and fiber optics, including the wires that comprise a system bus coupled to the processor. Transmission media may include or convey acoustic waves, light waves and electromagnetic emissions, such as those generated during radio frequency (RF) and infrared (IR) data communications. Common forms of computer-readable media include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD, any other optical medium, punch cards, paper tape, any other physical medium with patterns of holes, a RAM, a PROM, an EPROM, a FLASH-EEPROM, any other memory chip or cartridge, a carrier wave as described hereinafter, or any other medium from which a computer can read. 
       FIGS. 5A and 5B  illustrate a lens barrel  122  during the stereoscopic imaging process. The lens barrel  122  is directed at a distant target object  210 . By changing the position and alignment of refracting lens  104  in conjunction with the active region  206 , camera  100  may capture two viewing angles of target object  210 . 
       FIG. 5A  shows light beam  212  coming from target object  210  into lens  102 . Since target object  210  is distant, the light beam  212  from target object  210  is effectively parallel to the optical axis  204  of the lens barrel  122 . In  FIG. 5A , light beam  212  represents the center of the first (e.g., left) stereoscopic image captured by imager  106 , and field of view  213  represents the range (e.g., width and/or height) of the captured image. 
     Light beam  212  is refracted by refracting lens  104  towards the center of active region  206  of imager  106 . Since light beam  212  is initially offset from the optical axis  204  but is refracted to the center of active region  206  of the imager  106 , the image captured by imager  106  will have a different point of view and field of view  213  than a non-refracted image. 
       FIG. 5B  illustrates light beam  214  coming from target object  210  into lens  102 . Since target object  210  is distant, the light beam  214  from target object  210  is effectively parallel to the optical axis  204  of the lens barrel  122 . In  FIG. 5B , light beam  214  represents the center of the second (e.g., right) stereoscopic image captured by imager  106 , and field of view  215  represents the range (i.e., width or height) of the captured image. 
     Light beam  214  is refracted by refracting lens  104  towards the center of active region  206  of imager  106  Similar to  FIG. 5A , light beam  214  is initially offset from the optical axis  204 , but is refracted to the center of the active region  206  of imager  106 , causing the image captured by imager  106  to have a different point of view and field of view  215  from a non-refracted image. 
     The refracting lens configuration of  FIG. 5A  may produce a different image than the refracting lens configuration of  FIG. 5B  because each configuration has a different point of view and different field of view,  213  and  215 , respectively. Each field of view  213  and  215  gives the camera  100  a slightly different image range, and the different points of view expose the imager  106  to different angles of the target object  210 . While with distant objects these distinctions may be subtle, the differences may be sufficient to identify the respective 3D locations of the surfaces of the target object  210 . 
     During capture, lens barrel  122  may change configuration from  FIG. 5A  to  FIG. 5B , and vice versa, at a frequency comparable to the frame rate of imager  106 . For example if the imager  106  operates at a frequency of 60 images per second (60 fps) then lens barrel  122  must cycle between the configuration from  FIG. 5A  to the configuration of  FIG. 5B  within each 1/60 seconds. By continually changing the configuration, it is possible to obtain 3D video or images of target object  210  at a frame rate of 1/30 th  of a second, i.e., 1 left and right image pair per 1/30 seconds. 
     The depth perception of the device may be improved by increasing the ratio between the distance between the points of view and the distance of lens barrel  122  to the target object  210 . This can be accomplished by either moving the target object closer to lens  102  or increasing the radius of lens barrel  122 , lens  102 , and refracting lens  104 . This increases the divergence between fields of view  213  and  215 . 
       FIGS. 6A and 6B  illustrate two configurations of a lens barrel  122  having the target object  210  closer to lens barrel  122 , than in  FIGS. 5A and 5B . Alternatively,  FIGS. 6A  and  6 B could also illustrate a lens barrel  122  having a greater radius, as compared to  FIGS. 5A and 5B . 
       FIG. 6A  shows light beam  224  coming from target object  210  into lens  102 . Since target object  210  is nearby, the light beam  224  from target object  210  is slanted relative to the optical axis  204 . In  FIG. 6A , light beam  224  represents the center of the first stereoscopic image captured by imager  106 , and field of view  225  represents the range (i.e., width or height) of the captured image. 
     Similarly,  FIG. 6B  shows light beam  226  coming from target object  210  into lens  102 . Since target object  210  is nearby, the light beam  226  from target object  210  is slanted relative to the optical axis  204 . In  FIG. 6B , light beam  226  represents the center of the second stereoscopic image captured by imager  106 , and field of view  227  represents the range (i.e., width or height) of the captured image. 
     In both  FIGS. 6A and 6B , refracting lens  104  is aligned so that light beams  224  and  226  are refracted by refracting lens  104  towards the center of active region  206  of imager  106 . Since the arrangement in  FIG. 6A  has field of view  225  and  FIG. 6B  has field of view  227 , which are offset from one another but are refracted to the center of active region  206 , the images captured by imager  106  for each configuration will appear to be from different points of view. This provides greater differences in the resulting images and thereby may improve depth perception, compared to the configurations of  FIGS. 5A and 5B . 
     While embodiments herein are discussed primarily with respect to a system embodiment, an apparatus embodiment, and a lens barrel configuration, the present invention is not limited thereto. For example, different various lens barrel  122  configurations and adjustment mechanisms may be employed in positioning the refracting lens  104 . 
     For example, it may be possible to replace piezoelectric devices  202   a  and  202   b  with alternative mechanical or electrical devices. For example, an alternative embodiment may position the refracting lens at a static angle and rotate the lens barrel  122 , or the refracting lens  104 , at a rate corresponding to the frame rate of the imager  106 . This would allow for the same result as switching between different lens barrel  122  configurations at a given frame rate. Alternatively, an implementation may use the piezoelectric devices in conjunction with another mechanical or electrical approach to achieve the necessary synchronized positioning of the refracting lens  104  in accordance with the frame rate of the imager  106 . 
     Although embodiments of the invention are discussed primarily with respect to apparatuses for using a modified lens barrel and camera obtaining multiple images having different fields of view, and for obtaining three-dimensional images and video, other uses and features are possible. For example, an alternative embodiment may relate to a holographic projection device which can be formed by replacing imager  106  in lens barrel  122  with a projector LCD, thereby making it possible to alternatively project images onto a surface from two different points of view. Such dual or multiple projection-angle devices may create the appearance of a hologram on a target object. Various embodiments discussed herein are merely illustrative, and not restrictive, of the invention. 
     In the description herein, numerous specific details are provided, such as examples of components and/or methods, to provide a thorough understanding of embodiments of the present invention. One skilled in the relevant art will recognize, however, that an embodiment of the invention can be practiced without one or more of the specific details, or with other apparatuses, systems, assemblies, methods, components, materials, parts, and/or the like. In other instances, well-known structures, materials, or operations are not specifically shown or described in detail to avoid obscuring aspects of embodiments of the present invention. Thus embodiments of the present invention produce and provide SINGLE CAMERA DEVICE AND METHOD FOR 3D VIDEO IMAGING USING REFRACTING LENS. Although the present invention has been described in considerable detail with reference to certain embodiments thereof, the invention may be variously embodied without departing from the spirit or scope of the invention. Therefore, the following claims should not be limited to the description of the embodiments contained herein in any way.