Abstract:
A present novel and non-trivial system, device, and method for reducing image generating latency of an image presented on a display unit are disclosed. An image processing unit (“IPU”) may receive the image data set; receive (1) first navigation data of a first time from which second navigation data of the second time is determined or (2) second navigation data of a second time; receive third navigation data of the second time; compare the second navigation data with the third navigation data; and select a subset of the image data set in response to the comparison. Differences arising from the comparison, if any, may be used in determining the location and/or rotation of a cropping frame that selects the subset and forms a cropped image which is then provided to a display system, whereby the image represented in the subset is presented to the viewer.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     This invention pertains generally to the field of vehicles display units such as an aircraft display unit that provide information to the vehicle operator such as a pilot of an aircraft. 
     Description of the Related Art 
     The presentation a three-dimensional perspective of an image of the scene outside the aircraft is common. Prior to presenting the image, an image generating process must be performed. Generally, navigation data representative of the aircraft position (e.g., latitude, longitude, and altitude) and aircraft direction (e.g., heading) is used to retrieve terrain and/or obstacle data. Once this data is retrieved, an image data set representative of an image of a realistic, three-dimensional perspective of the scene outside the aircraft may be generated, provided to the display system, and subsequently displayed to the pilot. 
     Although the display of such image is beneficial to the pilot, the performance of the above-discussed steps creates an inherent latency in the image generation process. Although the speed of image generating processors in general continues to increase, there nevertheless exists an inherent latency induced by the image generating process. As such, the scene viewed by the pilot on the display unit closely approximates—but does not exactly match—the actual scene viewed by the pilot outside the aircraft. 
     BRIEF SUMMARY OF THE INVENTION 
     The embodiments disclosed herein present at least one novel and non-trivial system, device, and method for reducing the latency when generating an image. With the embodiments disclosed herein, the scene viewed by the pilot on the display unit will more closely match the actual scene located outside the aircraft. 
     In one embodiment, a system is disclosed for reducing image generating latency. The system may be comprised of a navigation data source and an image processing unit (“IPU”). The image data set could be representative of a predicted image of the scene outside an aircraft, where instant navigation data provided by the navigation data source may be used to determine predictive navigation data upon which the image data set is generated. Additionally, the system could include a source of an image data from which the image data set is generated, and a display system for presenting the image of on one or more display units. 
     In another embodiment, a device such as the IPU is disclosed for reducing image generating latency. This device may be configured to select a subset of the image data set based upon a comparison of two sets of navigation data acquired at different times. Differences arising from the comparison may be used in determining the location and/or rotation of a cropping frame within which the subset is selected and a cropped image is formed that is subsequently presented on the display unit. 
     In another embodiment, a method is disclosed for reducing image generating latency. When properly configured, the IPU may receive the image data set; receive (1) first navigation data of the first time from which second navigation data of the second time is determined or (2) second navigation data of the second time; receive third navigation data of the second time; compare the second navigation data with the third navigation data; and select a subset of the image data set in response to the comparison. In an additional embodiment, the IPU may provide the subset of the image data set to the display system, whereby the image represented in such subset is presented on one or more display units. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts a block diagram of a system for generating a reduced-latency image presented on a display unit. 
         FIG. 2A  provides an exemplary depiction of a Head-Down Display (“HDD”) unit. 
         FIG. 2B  provides an exemplary depiction of a Head-Up Display (“HUD”) unit. 
         FIG. 3A  provides an illustration of a predicted image represented in a image data set. 
         FIG. 3B  illustrates an illustration of a cropping frame. 
         FIG. 4A  illustrates a first placement of a cropping frame against an image of a predicted scene represented in an image data set. 
         FIG. 4B  illustrates the cropped image of  FIG. 4A . 
         FIG. 4C  illustrates a second placement of a cropping frame against an image of a predicted scene represented in an image data set. 
         FIG. 4D  illustrates the cropped image of  FIG. 4C . 
         FIG. 4E  illustrates a third placement of a cropping frame against an image of a predicted scene represented in an image data set. 
         FIG. 4F  illustrates the cropped image of  FIG. 4E . 
         FIG. 4G  illustrates a fourth placement of a cropping frame against an image of a predicted scene represented in an image data set. 
         FIG. 4H  illustrates the cropped image of  FIG. 4G . 
         FIG. 4I  illustrates a fifth placement of a cropping frame against an image of a predicted scene represented in an image data set. 
         FIG. 4J  illustrates the cropped image of  FIG. 4I . 
         FIG. 4K  illustrates a sixth placement of a cropping frame against an image of a predicted scene represented in an image data set. 
         FIG. 4L  illustrates the cropped image of  FIG. 4K . 
         FIG. 5  provides a flowchart illustrating a method for reducing image generating latency. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following description, several specific details are presented to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or in combination with other components, etc. In other instances, well-known implementations or operations are not shown or described in detail to avoid obscuring aspects of various embodiments of the invention. 
       FIG. 1  depicts a block diagram of a reduced latency, image generating system  100  suitable for implementation of the techniques described herein. The image generating system  100  of an embodiment of  FIG. 1  includes a navigation data source  110 , an image data source  120 , an image processing unit (“IPU”)  130 , and a display system  140 . 
     In an embodiment of  FIG. 1 , the navigation data source  110  could be comprised of a system or systems that provide navigation data information in an aircraft. For the purposes of the disclosures discussed herein, an aircraft could mean any vehicle which is able to fly through the air or atmosphere including, but not limited to, lighter than air vehicles and heavier than air vehicles, wherein the latter may include fixed-wing and rotary-wing vehicles. Although the following discussion will be drawn to aircraft and pilots, the embodiments herein may be applied to any vehicle and vehicle operator. 
     The navigation data source  110  may include any system for providing navigation data including, but not limited to, an air/data system, an attitude heading reference system, an inertial guidance system (or inertial reference system), and a global navigation satellite system (or satellite navigation system), all of which are known to those skilled in the art. The navigation data source  110  could provide navigation data including, but not limited to, geographic position, altitude, and heading. As embodied herein, aircraft position includes geographic position (e.g., latitude and longitude coordinates), altitude, or both. As embodied herein, aircraft orientation may include pitch, roll, and/or yaw information related to the attitude of the aircraft. The navigation data source  110  could provide the navigation data to the IPU  130  for subsequent processing as discussed herein. 
     As embodied herein, the navigation data source  110  could also include a flight management system (“FMS”) which could perform a variety of functions performed to help the crew in the management of the flight; these functions are known to those skilled in the art. These functions could include maintaining navigation data of the aircraft. 
     In an embodiment of  FIG. 1 , the image data source  120  may be comprised of any system or systems that could generate image data representative a three-dimensional perspective of the scene outside the aircraft including, but not limited to, a Synthetic Vision System (“SVS”)  122  and/or Enhanced Vision System (“EVS”)  124 . The SVS  122  may be comprised of, in part, a terrain database and a separate processor, where the terrain database is provided to such processor for creating synthetic image data representative of a three-dimensional perspective of the scene outside the aircraft for subsequently presented on a two-dimensional display unit. 
     The EVS  124  may be comprised of, in part, at least one infrared sensor and a separate processor. Each sensor (e.g., a camera) may be mounted on the aircraft for detecting infrared radiation and/or non-visible, near-infrared radiation emanating from the scene in front of the aircraft, and the separate processor may receive sensor data to create enhanced image data representative of a three-dimensional perspective of the scene outside the aircraft for subsequently presented on a two-dimensional display unit. 
     As embodied herein, image data source  120  could also be comprised of a combined SVS-EVS system which combines synthetic image data with enhanced image data to form combined synthetic-enhanced image data. As embodied herein, the image data source  120  comprised of the SVS  122 , the EVS  124 , and/or the combined SVS-EVS could provide synthetic image data, enhanced image data, and/or synthetic-enhanced image data, respectively, to the IPU  130  for subsequent processing as discussed herein. 
     In an embodiment of  FIG. 1 , the IPU  130  may be any electronic data processing unit which executes software or computer instruction code that could be stored, permanently or temporarily, in a digital memory storage device or computer-readable media (not depicted herein) including, but not limited to, RAM, ROM, CD, DVD, hard disk drive, diskette, solid-state memory, PCMCIA or PC Card, secure digital cards, and compact flash cards. The IPU  130  may be driven by the execution of software or computer instruction code containing algorithms developed for the specific functions embodied herein. The IPU  130  may be an application-specific integrated circuit (ASIC) customized for the embodiments disclosed herein. Common examples of electronic data processing units are microprocessors, Digital Signal Processors (DSPs), Programmable Logic Devices (PLDs), Programmable Gate Arrays (PGAs), and signal generators; however, for the embodiments herein, the term “processor” is not limited to such processing units and its meaning is not intended to be construed narrowly. For instance, the processor could also consist of more than one electronic data processing unit. As embodied herein, the IPU  130  could be a processor(s) used by or in conjunction with any other system of the aircraft including, but not limited to, the navigation data source  110 , the image data source  120 , and the display system  140 , or any combination thereof. 
     In the embodiment of  FIG. 1 , the display system  140  may receive image data from the IPU  130 . The display system  140  could include any unit that provides flight information including, but not limited to, a Head-Down Display (“HDD”) unit  142  and/or a Head-Up Display (“HUD”) unit  144 . As embodied herein, the disclosures may be applied to one or more portable devices including, but not limited to, laptop computer(s), smartphone(s), and/or tablet(s) which employ a display unit. 
     The HDD unit  142  may present flight information to the pilot or flight crew—information relevant to the instant or immediate control of the aircraft, whether the aircraft is in flight or on the ground. The HDD unit  142  is typically a unit mounted to an aircraft&#39;s flight instrument panel located in front of a pilot and below the windshield and the pilot&#39;s field of vision. The HDD unit  142  displays the same information found on a primary flight display (“PFD”), such as “basic T” information (i.e., airspeed, attitude, altitude, and heading). Although it provides the same information as that of a PFD, the HDD unit  142  may also display a plurality of indications or information including, but not limited to, selected magnetic heading, actual magnetic track, selected airspeeds, selected altitudes, altitude barometric correction setting, vertical speed displays, flight path angle and drift angles, flight director commands, limiting and operational speeds, mach number, radio altitude and decision height, final approach trajectory deviations, and marker indications. The HDD unit  142  is designed to provide flexible configurations which may be tailored to the desired configuration specified by a buyer or user of the aircraft. 
       FIG. 2A  provides an exemplary depiction of the HDD unit  142  for presenting flight information to the pilot or flight crew against the background of a three-dimensional image of terrain and sky; the HDD unit  142  could be employed as a display unit of the SVS  122 , the EVS  124 , or the combined SVS-EVS. It should be noted that the flight information depicted on the HDD unit  142  and has been made minimal for the sake of presentation and is not indicative of the plurality of indications or information with which it may be configured. 
     Returning to  FIG. 1 , the HUD unit  144  provides flight information to the pilot or flight crew in the pilot&#39;s forward field of view through the windshield, eliminating transitions between head-down to head-up flying. Similar to the HDD unit  142 , the HUD unit  144  may be tailored to the desired configuration specified by a buyer or user of the aircraft. As embodied herein, the HDD unit  142 , the HUD unit  144 , or any display unit may receive an image data set from IPU  130  for subsequent presentation. 
       FIG. 2B  provides an exemplary depiction of the HUD unit  144  for presenting flight information to the pilot or flight crew against the background of a three-dimensional image of terrain and sky, where such image is representative of and presented against the background of the actual terrain and sky located in the scene outside the aircraft; the HUD unit  144  could be employed as a display unit of the SVS  122 , the EVS  124 , or the combined SVS-EVS. It should be noted that the flight information depicted on the HUD unit  144  has been made minimal for the sake of presentation and is not indicative of the plurality of indications or information with which it may be configured. 
     In the embodiments of  FIGS. 3A and 3B , an image represented in an image data set and a cropping frame are illustrated, where such frame could be applied to the image data set to produce a cropped image that may be presented to the pilot. Referring to  FIG. 3A , an exemplar of an image  202  that could be represented in an image data set is shown, where the image  202  is comprised of a horizon line  204  dividing the sky  206  and the surface  208  on which a runway  210  sits. The image  202  could be indicative of a synthetic image presenting a three-dimensional perspective of a predicted scene outside the aircraft comprised of the sky  206  and the surface  208  such as the perspectives presented on the display units of  FIGS. 2A and 2B . 
     The image  202  could be generated by employing an image generating function(s) known to those skilled in the art and based upon a predictive navigation data such as, but not limited to, predictive aircraft position, predictive heading for a heading-based image, and/or predictive ground track for a track-based image. Predictive navigation data of a second time may be based upon instant navigation data of a first time and determined by employing navigation predicting function(s) known to those skilled in the art. 
     An image reference point (“IRP”)  212  (shown as a plus sign) could be a reference point of the image  202  about which the image data set is generated. For the purpose of illustration only and not of limitation, the IRP  212  could correspond to predictive aircraft position and/or predictive heading and may be located in the center of the image. For example, if the size of the image data set is configured as 1600 pixels by 1200 pixels, the IRP  212  corresponding to predictive aircraft position and/or predictive heading could coincide with pixel location (800, 600), a point assumed as the center of the image for the purpose of illustration only. For the purpose of discussion herein, the horizontally-level horizon  204  and the location of the horizon  204  below the IRP  212  as shown in  FIG. 3A  is indicative of straight-and-level flight. 
     Referring to  FIG. 3B , an exemplar of a cropping frame  214  that could be employed to crop the image  202  of the image data set by a cropping function that includes the disclosures disclosed herein. A frame reference point  216  (“FRP”) (shown as a circle) could be a reference point of the frame  214  from which a subset of the image data set is selected. For the purpose of illustration only and not of limitation, the FRP  216  could correspond to the instant aircraft orientation and instant navigation parameters of a second time, and may be located in the center of the frame. For example, if the frame is configured as 1400 pixels by 1050 pixels, the FRP  216  could coincide with pixel location (700, 525), a point assumed as the center of the frame for the purpose of illustration only. 
     The advantages and benefits of the embodiments discussed herein may be disclosed by illustrating in  FIGS. 4A through 4L  the cropping of the image in a plurality of examples. In the example of  FIGS. 4A and 4B , assume that the predictive navigation data determined at a previous time are the same as the instant navigation data at the instant time; that is, a prediction function made an accurate prediction. As shown in  FIG. 4A , the image indicative of straight-and-level flight (as shown in  FIG. 3A ) and the predicted scene outside the aircraft (in which a runway appears directly ahead) have been generated based upon predictive navigation data, where the IRP corresponds to predictive navigation data and is centered within the image. 
     Moreover, the location of the FRP could depend upon the differences between instant navigation data and the predictive navigation data. Where there are no differences, the FRP may be configured to coincide with the IRP as shown in  FIG. 4A . Then, the frame may be employed to crop the image, selecting a subset of the image data set representative of the cropped image (i.e., the image appearing within the frame). When the subset of the image data set is sent to the display unit, the cropped image of  FIG. 4B  centered on the FRP may be presented to the pilot (the IRP and FRP are not visible). 
     In the example of  FIGS. 4C and 4D , assume that the predictive navigation data determined at a previous time correspond to straight-and-level flight, but the instant navigation data at the instant time correspond to a climbing attitude. As shown in  FIG. 4C , the image indicative of straight-and-level flight and the predicted scene outside the aircraft have been generated based upon predictive navigation data, where the IRP corresponds to predictive navigation data and is centered within the image. 
     As stated above, the location of the FRP could depend upon the differences between instant navigation data and the navigation data. Here, the FRP is located above the IRP because the instant attitude of a climb exceeds the predictive attitude of straight-and-level. The screen or pixel distance between the FRP and the IRP may be commensurate with the difference between instant and predictive orientation measurements. Where the difference is commensurate with a known number of pixel rows, the FRP may be located above the IRP by such number of pixel rows. After the location of the FRP has been determined, the frame may be employed to crop the image, selecting a subset of the image data set representative of the cropped image. When the subset of the image data set is sent to the display unit, the cropped image of  FIG. 4D  centered on the FRP may be presented to the pilot. 
     In the example of  FIGS. 4E and 4F , assume that the predictive navigation data determined at a previous time correspond to straight-and-level flight, but the instant navigation data at the instant time correspond to a descending attitude. As shown in  FIG. 4E , the image indicative of straight-and-level flight and the predicted scene outside the aircraft have been generated based upon predictive navigation data, where the IRP corresponds to predictive navigation data and is centered within the image. 
     As stated above, the location of the FRP could depend upon the differences between instant navigation data and the predictive navigation data. Here, the FRP is located below the IRP because the predictive attitude of straight-and-level exceeds the instant attitude of a descent. The screen or pixel distance between the FRP and the IRP may be commensurate with difference between instant and predictive orientation measurements; in this example, the FRP may be located below the IRP by a known number of pixel rows commensurate with the measurement of the difference. After the location of the FRP has been determined, the frame may be employed to crop the image, selecting a subset of the image data set representative of the cropped image. When the subset of the image data set is sent to the display unit, the cropped image of  FIG. 4F  centered on the FRP may be presented to the pilot. 
     In the example of  FIGS. 4G and 4H , assume that the predictive navigation data determined at a previous time are the same as the instant navigation data at the instant time. As shown in  FIG. 4G , the image indicative of a level turn to the left and the predictive scene outside the aircraft have been generated based upon predictive navigation data, where the IRP corresponds to predictive navigation data and is centered within the image. 
     As stated above, the location of the FRP could depend upon the differences between instant navigation data and the predictive navigation data. Where there are no differences, the FRP may be configured to coincide with the IRP as shown in  FIG. 4G . Then, the frame may be employed to crop the image, selecting a subset of the image data set representative of the cropped image. When the subset of the image data set is sent to the display unit, the cropped image of  FIG. 4H  centered on the FRP may be presented to the pilot. 
     In the example of  FIGS. 4I and 4J , assume that the predictive navigation data determined at a previous time correspond to a level turn to the left at a given turning angle, but the instant navigation data at the instant time correspond to a level left turn at a greater turning angle. As shown in  FIG. 4I , the image indicative of a level, turning flight and the predicted scene outside the aircraft have been generated based upon predictive navigation data, where the IRP corresponds to predictive navigation data and is centered within the image. 
     As stated above, the location of the FRP could depend upon the differences between instant navigation data and the predictive navigation data. Here, the FRP is located to the left of the IRP because the instant heading is located to the left of the predictive heading due to the greater turning angle. In addition, the frame is rotated clockwise because the instant roll attitude exceeds the predictive roll attitude. 
     The screen or pixel distance between the FRP and the IRP may be commensurate with the difference between instant navigation data and predictive navigation data. Where the difference is commensurate with a known number of pixel columns, the FRP may be located to the left of the IRP by such number of pixel columns. Also, the clockwise rotation of the frame about the FRP may be commensurate with the difference between the measurements of instant roll attitude and predictive roll attitude. After the location of the FRP and the rotation of the frame have been determined, the frame may be employed to crop the image, selecting a subset of the image data set representative of the cropped image. When the subset of the image data set is sent to the display unit, the cropped image of  FIG. 4J  centered on the FRP may be presented to the pilot. 
     In the example of  FIGS. 4K and 4L , assume that the predictive navigation data determined at a previous time correspond to a level turn to the left at a given angle, but the instant navigation data at the instant time correspond to a level left turn at a lesser turning angle. As shown in  FIG. 4K , the image indicative of a level, turning flight and the predicted scene outside the aircraft have been generated based upon predictive navigation data, where the IRP corresponds to predictive navigation data and is centered within the image. 
     As stated above, the location of the FRP could depend upon the differences between instant navigation data and the predictive navigation data. Here, the FRP is located to the right of the IRP because the instant heading is located to the right of the predictive heading due to the lesser turning angle. In addition, the frame is rotated counterclockwise because the predictive roll attitude exceeds the instant roll attitude. 
     As stated above, the screen or pixel distance between the FRP and the IRP may be commensurate with the difference between instant navigation data and predictive navigation data. Where the difference is commensurate with a known number of pixel columns, the FRP may be located to the right of the IRP by such number of pixel columns. Also, the counterclockwise rotation of the frame about the FRP may be commensurate with the difference between the measurements of instant roll attitude and predictive roll attitude. After the location of the FRP and the rotation of the frame have been determined, the frame may be employed to crop the image, selecting a subset of the image data set representative of the cropped image. When the subset of the image data set is sent to the display unit, the cropped image of  FIG. 4L  centered on the FRP may be presented to the pilot. 
     In an embodiment of  FIG. 5 , flowchart  300  discloses an example of a method for generating a reduced-latency image presented on a display unit, where the IPU  130  may be programmed or configured with instructions corresponding to the following modules embodied in the flowchart. Also, the IPU  130  may be a processor of a module such as, but not limited to, a printed circuit board having one or more input interfaces to facilitate the two-way data communications of the IPU  130 , i.e., to facilitate the receiving and providing of data. As necessary for the accomplishment of the following modules embodied in the flowchart, the receiving of data is synonymous and/or interchangeable with the retrieving of data, and the providing of data is synonymous and/or interchangeable with the making available or supplying of data. 
     Flowchart  300  begins with module  302  with the receiving of first navigation data of the first time or second navigation data of the second time. In one embodiment, the first navigation data could be received from the navigation system and applied to a navigation predicting function(s) to determine second navigation data of the second time. In another embodiment, the second navigation data could be received from the source of the image data set at the same time the image data set is received (as discussed in module  304 ). The first navigation data and the second navigation data could be representative of at least aircraft orientation and/or direction, and such first and second navigation data could be data included in the fourth and fifth navigation data, respectively. 
     The method continues with module  304  with the receiving of an image data set. The image data set may be representative of an image of a predicted scene outside an aircraft. The image data set could be generated from fourth navigation data of a first time received from the navigation system that is applied to a navigation predicting function(s) to determine fifth navigation data of a second time. A correspondence could be set between an IRP of the image of the image data set and the fifth navigation data; that is, a correspondence could be set between the IRP and the aircraft position and/or aircraft direction represented in the fifth navigation data. In an additional embodiment, the image could be a synthetic image presenting a three-dimensional perspective of the predicted scene outside the aircraft, where terrain data has been retrieved from a terrain data source (e.g., a terrain database) based upon the predictive navigation data. 
     The method continues with module  306  with the receiving third navigation data at the second time, where the third navigation data could be representative of at least aircraft orientation and/or direction. The method continues with module  308  with the comparing of second navigation data of the second time with the third navigation data of the second time. The comparison could determine the differences, if any, between at least aircraft orientation and/or direction of the second navigation data and the third navigation data. 
     The method continues with module  310  with the selecting a subset of the image data set in response to the comparison. If the result of the comparison indicates an absence of differences between aircraft orientations and/or directions, the FRP for a frame and the IRP of the image may coincide. Then, the frame may be employed to crop the image, selecting a subset of the image data set representative of the cropped image. 
     If the result of the comparison indicates a presence of one or more differences between aircraft orientations and/or directions, then the location of the FRP and/or the rotation of the frame could depend upon these difference(s), where the screen or pixel distance between the FRP and the IRP and/or angular rotation of the frame may be commensurate with the difference(s). Then, the frame may be employed to crop the image, selecting a subset of the image data set representative of the cropped image. 
     In an additional embodiment, the image data set could be provided to a display unit configured to receive such data and present the image represented in the image data set on the screen of the display unit. Where the FRP coincides with the center of the frame and the image occupies the entire screen, the image may be centered on the screen. Then, the flowchart proceeds to the end. 
     It should be noted that the method steps described above may be embodied in computer-readable media as computer instruction code. It shall be appreciated to those skilled in the art that not all method steps described must be performed, nor must they be performed in the order stated. 
     As used herein, the term “embodiment” means an embodiment that serves to illustrate by way of example but not limitation. 
     It will be appreciated to those skilled in the art that the preceding examples and embodiments are exemplary and not limiting to the scope of the present invention. It is intended that all permutations, enhancements, equivalents, and improvements thereto that are apparent to those skilled in the art upon a reading of the specification and a study of the drawings are included within the true spirit and scope of the present invention. It is therefore intended that the following appended claims include all such modifications, permutations and equivalents as fall within the true spirit and scope of the present invention.