Patent Publication Number: US-11665319-B2

Title: Augmented reality display device, and apparatus comprising same

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to augmented reality and in particular, to an augmented reality display device and an apparatus comprising the same. 
     BACKGROUND OF THE INVENTION 
     In the field of augmented reality, augmented reality devices are worn by a user to provide the user with an interactive experience of a real-world environment, in which objects that reside in the real world are enhanced by computer-generated perceptual information. The computer-generated perceptual information can be any of visual information, auditory information, haptic information, and the like. 
     Visual augmented reality devices typically comprise one or more imaging devices and/or optical sensors that output information that is processed and combined with or “overlaid on” an image of the real world. The combined image is usually displayed on goggles or eyewear worn by the user. 
     For example, International PCT Application Publication No. WO 2013098366 to Luong et al. describes an apparatus for viewing augmented reality, comprising: a mask comprising a frame comprising a body onto which an inextensible strip is mounted, the latter defining a surface for bearing on the face of a user, and a strap for holding the frame on the face of the user, with the bearing surface thereof bearing on the face around the eyes; and at least one optical device comprising a semitransparent screen attached to the frame and opposite the eye of the user, and a projection system attached to the frame, said projection system being suitable for ensuring the projection of an augmented reality image onto the semitransparent screen, characterized in that it is free of any means for adjusting the position of the screen relative to the bearing surface when the mask is placed on the face of a user, and in that the relative positions of the screen, the bearing surface, and the projection system are translatably and rotatably invariant in all of the six degrees of freedom, regardless of the position of the mask on the face of the user, such that the position of the exit pupil of the optical device relative to the user is only adjusted by moving the mask relative to the face of the user. 
     Conventional augmented reality goggles or eyewear are generally bulky and are typically not physically compatible with headwear or facial items worn by the user, such as a helmets, breathing apparatuses, and the like. 
     Improvements are generally desired. It is therefore an object of the present invention at least to provide a novel augmented reality display device and an apparatus comprising the same. 
     SUMMARY OF THE INVENTION 
     It should be appreciated that this summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to be used to limit the scope of the claimed subject matter. 
     Thermal imaging is a technique to overcome low light and poor visibility. Existing thermal imaging augmented reality systems for firefighters are limited in compatibility with existing firefighter helmets and self-contained breathing apparatus (SCBA). Certain other augmented reality systems add virtual elements to the real environment for training and simulation purposes, but do not aid in identifying and locating people in the real environment. 
     Accordingly, there is a need for an augmented reality display system that is compatible with any existing firefighter helmet and SCBA allowing a user to see an augmented reality view of the environment to more easily identify and locate distressed persons. 
     To address this need, the present invention provides a method for firefighters to identify and locate people in a burning building where low light, dust, smoke and debris can obscure the firefighter&#39;s view of the surroundings. The method described herein combines thermal imaging with edge detection image processing to specifically highlight human temperature objects in the firefighter&#39;s field of view, allowing for quick identification and location of persons in poor visibility environments. 
     Also disclosed herein is an augmented reality display system and mounting assembly that is compatible with existing firefighter helmets and SCBA without modification. 
     Headgear mounted visual display systems may have to be integrated into headgear by OEM manufacturers. These display systems may lack wide compatibility and may not be used as add-ons with standalone headgear and self-contained breathing apparatus (SCBA) in use today. 
     Disclosed herein, is an augmented reality (AR) display system that is compatible with a variety of protective or functional headgear without having to modify the headgear to accept the display system. 
     Accordingly, in one aspect, there is provided an augmented reality visual display system for attaching to headgear, the display system comprising: an augmented reality display unit; a thermal imaging camera within the display unit for capturing a thermal view of the environment corresponding to the user&#39;s field of view; a display screen attached to the display unit for displaying augmented reality information; a mounting assembly attached to the display unit for removably attaching the display system to the headgear so that the display screen is positioned in front of the user&#39;s eyes; an image processing system coupled to the camera and the display screen, for receiving the thermal view from the camera, identifying human temperature objects in the thermal view and outputting the human temperature objects to the display screen so that the user sees an augmented reality view of human temperature objects in the environment. 
     The thermal imaging camera may be proximate to the user&#39;s eyes and pointed away from the user. The display screen may be transparent allowing the user to view the environment through the display screen. The mounting assembly may attach the display system to the headgear on the outside of a self-contained breathing apparatus mask worn by the user. The mounting assembly may include at least one connector for removably attaching the display system to the headgear. The display system may further comprise a GPS transceiver. The display system may further comprise a gyroscope. The display system may further comprise wireless network connectivity. The augmented reality output may be wirelessly transmitted to a remote location, wherein the augmented reality output may be transmitted and stored on a media storage device. 
     In another aspect, there is provided a mounting assembly for attaching a display screen to a headgear, the assembly comprising: at least one connector for removably attaching to the headgear; a display mount secured to the connector. 
     The display mount may be pivotally attached to a display screen, such that the screen is positioned in front of the user&#39;s eyes and translates vertically with respect to the display mount. The display screen may be attached to the display mount by two parallel arms having opposable ends, the first end of each arm being pivotally connected to the display screen, the second end of each arm being pivotally connected to the display mount. The connector may be capable of attaching to an exposed surface of the headgear. The display mount may comprise a support positioned perpendicular to the brim of the headgear and a base positioned parallel to the brim of the headgear, wherein the connector may be capable of securing to the base of the display mount at various points more proximate or distal to the center of the base. 
     In another aspect, there is provided a firefighting method for identifying and locating human temperature objects comprising: capturing a thermal view of the environment; identifying objects in the thermal view; creating a virtual view of objects identified in the thermal view; overlaying the thermal view and the virtual view to create a fusion view; identifying objects in the fusion view with a thermal value corresponding to human body temperature; outputting the identified human temperature objects to a display screen. 
     The thermal view may be corrected for ambient temperature in the environment. The display screen may be transparent. The identification of human temperature objects in the fusion view may be accomplished by comparison against a pre-calibrated thermal value. 
     In still another aspect, there is provided an augmented reality display device, comprising: a display unit comprising a thermal camera configured to capture image frames, an image projector, and a display screen; a processing unit comprising processing structure in communication with the thermal camera and the image projector, the processing structure being configured to process the captured image frames and output processed image frames to the image projector, and a battery; and a strap connecting the display unit and the processing unit. 
     The display unit may comprise a base shaped to engage a headgear. The base may comprise at least one feature shaped to abut a brim of the headgear. The base may comprise an upper tab and a lower tab defining a groove therebetween, the groove being shaped to accommodate a brim of the headgear. The augmented reality display device may further comprise a moveable assembly coupled to the base, the moveable assembly having the display screen connected thereto. The moveable assembly may further have at least one of the image projector and thermal camera connected thereto. The moveable assembly may comprise a linkage arm assembly. The moveable assembly may comprise a four-bar linkage. 
     The strap may be an adjustable strap having an adjustable length. The adjustable strap may comprise at least one buckle configured to engage teeth. The adjustable strap may comprise a first strap portion connected to the display unit, and a second strap portion connected to the processing unit. 
     The augmented reality display device may further comprise a digital gyroscope outputting a signal to the processing structure, the processing structure processing the signal and providing a compass heading indicator in the processed image frames. 
     In one embodiment, there is provided an augmented reality display apparatus, comprising: the augmented reality display device described above; and headgear comprising a brim, the display unit being shaped to engage the brim. 
     In another aspect, there is provided an augmented reality display device, comprising: at least one mounting feature for engaging a headgear; a thermal camera configured to capture image frames; processing structure in communication with the thermal camera and the image projector, the processing structure being configured to process the captured image frames and output processed image frames; a battery; an image projector configured to display the processed image frames; and a display screen, the display screen being translatably moveable relative to the at least one feature for engaging the headgear. 
     The augmented reality display device may further comprise: a base shaped to engage the headgear; and a moveable assembly connected to the base, the moveable assembly having the display screen connected thereto. The moveable assembly may comprise a linkage arm assembly. 
     The thermal camera, the at least one mounting feature for engaging the headgear, the image projector and the display screen, may be accommodated within a display module, the processing structure and the battery may be accommodated within a processing unit, and the augmented reality display device may further comprise: a strap connecting the display unit and the processing unit. The strap may be an adjustable strap having an adjustable length. The adjustable strap may comprise at least one buckle configured to engage teeth. The adjustable strap may comprise a first strap portion connected to the display unit, and a second strap portion connected to the processing unit. 
     The augmented reality display device may further comprise a digital gyroscope outputting a signal to the processing structure, the processing structure processing the signal and providing a compass heading indicator in the processed image frames. 
     In still another aspect, there is provided an augmented reality display apparatus, comprising: a headgear having a brim; and an augmented reality display device having at least one mounting feature engaging the brim, the augmented reality display device comprising: a thermal camera configured to capture image frames, an image projector, a display screen, processing structure in communication with the thermal camera and the image projector, the processing structure being configured to process the captured image frames and output processed image frames to the image projector, and a battery, the display screen being moveable relative to the at least one mounting feature engaging the brim. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments will now be described more fully with reference to the accompanying drawings in which: 
         FIG.  1    is a schematic block diagram of an augmented reality display system; 
         FIG.  2    is a perspective view of the augmented reality display system of  FIG.  1   , shown in use and worn by a user; 
         FIG.  3    is a top view of the augmented reality display system of  FIG.  1   ; 
         FIG.  4    is a side view of the augmented reality display system of  FIG.  2   , shown in use and worn by the user wearing a mask of a self-contained breathing apparatus (SCBA); 
         FIG.  5    is an exploded perspective view of a display unit forming part of the augmented reality display system of  FIG.  1   ; 
         FIG.  6    is a schematic block diagram of an image processing system forming part of the augmented reality display system of  FIG.  1   ; 
         FIG.  7    is an exploded perspective view of a mounting assembly forming part of the augmented reality display system of  FIG.  1   , and a helmet being used therewith; 
         FIG.  8    is an exploded perspective view of a connector and locking members forming part of the mounting assembly of  FIG.  7   ; 
         FIG.  9    is a top view of the mounting assembly of  FIG.  7   ; 
         FIG.  10    is a flowchart of human temperature object identification method used by the augmented reality display system of  FIG.  1   ; 
         FIG.  11    is an example of a thermal view image of an environment captured by a thermal imaging camera; 
         FIG.  12    is an example of a virtual view image, rendered by detecting edges of objects in the thermal view of  FIG.  11   ; 
         FIG.  13    is an example of an augmented reality view image, in which human temperature objects identified in the thermal view image of  FIG.  11    are highlighted; 
         FIGS.  14 A and  14 B  are examples of color and greyscale images generated using the human temperature object identification method of  FIG.  10   ; 
         FIG.  15    is a perspective view of another embodiment of an augmented reality display apparatus; 
         FIG.  16    is a schematic block diagram of an augmented reality display device forming part of the augmented reality display apparatus of  FIG.  15   ; 
         FIG.  17    is a side view of the augmented reality display apparatus of  FIG.  15   ; 
         FIG.  18    is a top view of the augmented reality display apparatus of  FIG.  15   ; 
         FIG.  19 A  is an exploded perspective view of the augmented reality display apparatus of  FIG.  15   ; and 
         FIG.  19 B  is an enlarged fragmentary view of a portion of the augmented reality display apparatus indicated in  FIG.  19 A . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The foregoing summary, as well as the following detailed description of certain examples will be better understood when read in conjunction with the appended drawings. As used herein, an element or feature introduced in the singular and preceded by the word “a” or “an” should be understood as not necessarily excluding the plural of the elements or features. Further, references to “one example” or “one embodiment” are not intended to be interpreted as excluding the existence of additional examples or embodiments that also incorporate the described elements or features. Moreover, unless explicitly stated to the contrary, examples or embodiments “comprising” or “having” or “including” an element or feature or a plurality of elements or features having a particular property may include additional elements or features not having that property. Also, it will be appreciated that the terms “comprises”, “has”, “includes” means “including by not limited to” and the terms “comprising”, “having” and “including” have equivalent meanings. 
     As used herein, the term “and/or” can include any and all combinations of one or more of the associated listed elements or features. 
     It will be understood that when an element or feature is referred to as being “on”, “attached” to, “connected” to, “coupled” with, “contacting”, etc. another element or feature, that element or feature can be directly on, attached to, connected to, coupled with or contacting the other element or feature or intervening elements may also be present. In contrast, when an element or feature is referred to as being, for example, “directly on”, “directly attached” to, “directly connected” to, “directly coupled” with or “directly contacting” another element of feature, there are no intervening elements or features present. 
     It will be understood that spatially relative terms, such as “under”, “below”, “lower”, “over”, “above”, “upper”, “front”, “back” and the like, may be used herein for ease of description to describe the relationship of an element or feature to another element or feature as illustrated in the figures. The spatially relative terms can however, encompass different orientations in use or operation in addition to the orientation depicted in the figures. 
     Referring to  FIG.  1   , illustrated therein is a block diagram of an augmented reality (AR) display system  100 , in accordance with an embodiment. The display system  100  includes headgear  106  worn by a user  108 . The headgear  106  includes functional or protective headgear normally worn by the user  108  in the performance of the user&#39;s duties. For example, the headgear  106  may be a cap or a helmet worn by first responders such as police, paramedics, and firefighters. The headgear  106  may be a protective helmet for construction, mining or other jobs requiring head protection. In accordance with an embodiment, the headgear  106  includes a Self-Contained Breathing Apparatus (SCBA) mask worn by the user  108 . 
     The display system  100  includes a display unit  102 . The display unit  102  receives a data input  112 . The data input  112  includes a view of the environment  116  to be augmented. The data input  112  may include data  118  relating to equipment  120  carried by the user  108  that is interfaced with the display unit  102 . For example, if the user  108  is a firefighter who is carrying a Self-Contained Breathing Apparatus (SCBA) tank  126 , the display unit  102  may be interfaced with the SCBA tank  126 . 
     The display unit  102  generates an augmented reality (AR) view of the environment  114  based on the data input  112 . The AR view  114  aids the user  108  in the performance of the user&#39;s duties. For example, if the user  108  is a firefighter working in a burning building, the AR view  114  may include objects in the environment  124  that are hidden by smoke and cannot be seen directly by the user&#39;s eyes  110 . If the firefighter is carrying a SCBA tank  126  that is interfaced with the display unit  102 , the AR view  114  may include the oxygen level  134  in the SCBA tank  126 . The AR view  114  may also include a date  128 , a time  130 , a compass  136 , and a battery level  132  for the display system  100  and/or user equipment  120 . The AR view  114 , may include further information  138  that is relevant to the work the user  108  is engaged in. 
     The display system  100  includes a display screen  122  connected to the display unit  102 . The display screen  122  shows the user  108  the AR view  114  generated by the display unit  102 . 
     The display system  100  includes an attachment  104  for attaching the display unit  102  to the headgear  106 . The attachment  104  attaches the display unit  102  to an exposed surface  142  of the headgear  106 . The exposed surface  142  is not covered by the user  108  when the user  108  is wearing the headgear  106 . For example, the exposed surface  142  may be a brim extending outward from the portion of the headgear  106  contacting the user  108 . The attachment  104  to the exposed surface  142  allows for the display system  100  to be used as an add-on without modifying the headgear  106  to accept the display system  100 . 
     Referring to  FIGS.  2  and  3   , illustrated therein is an AR display system  200 , in accordance with an embodiment. The display system  200  includes headgear  202  worn by a user  205 . The headgear  202  is a firefighter helmet  203 . The helmet  203  includes a brim  204  projecting outward from the portion of the helmet  203  that is in contact with the user  205 . 
     The display system  200  includes an AR display  206 . The AR display  206  includes a spherical display screen  208 . The display screen  208  shows the user  205  an AR view (such as AR view  114  of  FIG.  1   ) of the user&#39;s environment  232 . 
     Compared to other display systems which provide a relatively small display screen, the present system  200  includes a display screen  208  that is large. The display screen  208  has dimensions that substantially covers the user&#39;s entire field of view. This allows for the user  205  viewing the AR view on the display screen  208  to have a degree of depth perception equal to the user&#39;s depth perception when viewing the environment directly. For example, an object  272  in the environment  232 , when viewed on the display screen  208 , will appear similar in size and position as the when the object  272  is seen by the user  205  directly. This allows the user  208  to easily navigate the environment  232  while looking at the screen  208 . 
     A further advantage of the large display screen  208  is that it allows for a large viewing area  276  on the screen  208 . This allows the user  205  to see small objects and fine details on the screen  208  with less eye strain than if the display screen  208  and viewing area  276  was smaller. A large viewing area  276  also allows for more information (such as  124 ,  128 ,  130 ,  132 ,  134 ,  136 ,  128  in  FIG.  1   ) to be displayed simultaneously on the screen  208 , so that the user  205  is able to clearly distinguish and selectively focus on each to aid the user  205  in the performance of the user&#39;s duties. 
     Now referring to  FIG.  2   , the display screen  208  is positioned in front of the user&#39;s eyes  222 , when the display system  200  is attached to the helmet  203 . Thus, the display system  200  provides the user  205  with the flexibility to use both hands (not shown) freely while viewing the display screen  208  without having to hold any part of the display system  200 . 
     The display screen  208  may be transparent. A transparent display screen  208  allows the user  205  to selectively focus on the display screen  208  or the environment  232 . The user  205  may look through the display screen  208  to focus on the environment  232  directly as shown by arrow  228 . Alternatively, the user  208  may focus on the display screen  208  as shown by arrow  230 . The ability to selectively focus on the display screen  208  or the environment  232  allows the user  205  to perceive depth. Further, the user  205  may compare the augmented reality view on the display screen  208  to the direct view of the environment  232  to aid the user  205  in the performance of duties. 
     The display system  200  includes a mounting assembly  212 . The mounting assembly attaches the AR display  206  to the helmet  203 . 
     The mounting assembly  212  includes at least one connector  214 . The connector  214  removably clamps to the brim  204  of the helmet  203 . The connector  214 , maintains the position of the mounting assembly  212  (and attached AR display  206 ) relative to the helmet  203 . 
     As shown in  FIG.  3   , the mounting assembly  212  may be attached to the brim  204  of the helmet  203  by two connectors  214 . The two connectors  214  allow for the mounting assembly  212  to be better fixed on the helmet  203  than if a single connector  214  is used. Further, the use of two connectors  214  distributes the weight of the AR display  206  and mounting assembly  212  across two points on the brim  204 . 
     Referring to  FIG.  4   , illustrated therein is the augmented reality display system  200  of  FIGS.  2  and  3   , shown in relation to a user&#39;s eye  222  and a SCBA mask  224  worn by the user  205 . 
     The display system  200  is independent of the SCBA mask  224 , having all components of the system  200  outside the mask  224 . This configuration offers an advantage over display systems for first responders wherein certain components are located inside the mask and other components are outside the mask with wiring running between. A limitation of these display systems is that components are incorporated into SCBA systems by OEM manufacturers and cannot be installed by the user  205 . 
     The present display system  200 , being independent of the mask  224 , allows for easy installation by the user  205  and is widely compatibility as an add-on with a range of existing SCBA systems and headgear. A further advantage of the display system  200  being independent of the mask  224  is the ability for the user  205  to move the display screen  208  for an unobstructed view of the environment without first removing the headgear  202  and mask  224 , thereby reducing the user&#39;s exposure to environmental hazards in a rescue situation. 
     Referring to  FIGS.  2  and  4   , the mounting assembly  212  includes a display mount  216  attached to the connector  214 . The display mount  216  is attached to the AR display  206 . The display unit  210  of the AR display  206  is pivotally connected to the display mount  216  of the mounting assembly  212  via a pair of parallel arms  218 . The pair of parallel arms  218  allow the AR display  206  to translate vertically with respect to the display mount  216 . The position of the display screen  208  is fixed relative to the display unit  210 . A vertical translation of the display unit  210  is accompanied by a corresponding vertical translation of the display screen  208 . 
     Now referring to  FIG.  4   , illustrated therein is the vertical translation  220  of the AR display  206  relative to the display mount  216 . The vertical translation  220  is between a first position (solid lines)  234  and a second position (dashed lines)  236 . In the first position  234 , the display screen  208  is positioned in front of the user&#39;s eyes  222 . In the second position  236 , the display screen  208  is translated upward, out of the user&#39;s sightline. 
     The ability to move the display screen  208  allows the user  205  to choose between seeing an AR view (such as AR view  114  of  FIG.  1   ) of the environment  232  when the screen  208  is in the first position  234 , and an unobstructed direct view of the environment  232  when the screen  208  is in the second position  236 . 
     The display system  200 , may further include a locking mechanism (not shown) to allow the user  205  to lock the AR display  206  in the first position  234  or the second position  236 . 
     Referring again to  FIG.  2   , the display system  200  includes a display unit  210 . The display unit contains components for capturing a thermal view of the user&#39;s environment, rendering an augmented reality view of the environment  232  and outputting the augmented reality view to the display screen  208 . 
     Referring to  FIG.  5   , illustrated therein are the components of the display unit  210 . The display unit includes a front shell  238  and a back shell  240 . The front shell  238  and back shell  240  are opposable with respect to one another. The front shell includes at least one projection  242 . The back shell includes at least one indent  244 . The front shell  238  and the back shell  240  are complimentary such that the projection  242  fits into the indent  244  where the front shell  238  contacts the back shell  240 . Together, the front shell  238  and back shell  240  enclose a space  246 . The space  246  enclosed by the front shell  238  and back shell  240  contains the internal components of the display unit  210 . 
     The display unit  210  includes a thermal imaging camera  248 . The thermal camera  248  is preferably a FLIR Boson or similar thermal imaging camera, having small size, light weight and low energy consumption suitable for integration into portable battery powered equipment. Preferably the thermal camera  248  has at least 8× continuous zoom to allow for dynamic focusing. The thermal camera  248  should be capable of image capture at a frame rate of 60 Hz. The thermal camera  248  is positioned adjacent to an aperture  252  in the front shell  238 . The camera  248  includes a lens  250 . The lens  250  is pointed through the aperture  252  to view the environment  232 . The camera  248  (and lens  250 ) should be positioned proximate to the user&#39;s eyes to capture the user&#39;s field of view. Ideally, the camera  248  should be positioned between the user&#39;s eyes so that the camera&#39;s field of view tracks the direction in which the user is looking. 
     The display unit  210  includes a dual camera  254 . The dual camera  254  includes two optical sensors  256 . The dual camera  254  is positioned adjacent to apertures  258  in the front shell  238  such that the optical sensors  256  are pointed through the apertures  258  to view the environment  232 . The use of two optical sensors  256  allows for depth perception when the dual camera  254  is scanned across a room. The dual camera  254  combines the view of the environment  232  captured by each optical sensor  256  into a single image. The output from the dual camera  254  can be wirelessly transmitted to a remote location, such as a command center, where fire rescue is coordinated. The output that is transmitted may also be recorded to a media storage device for later viewing. In this way, the recorded output can be reviewed for analysis of firefighter skill and execution and for training purposes. 
     The display unit  210  includes a gyroscope  262 . The gyroscope  262  allows for a compass (such as compass  136  of  FIG.  1   ) to be displayed on the display screen  208 . The compass provides the user with orientation information in situations where poor visibility can cause disorientation. 
     The display unit  210  may include a GPS transceiver  280 . The GPS transceiver  280  allows for location tracking of a user (such as user  205  in  FIGS.  2  and  4   ) by transmitting the user&#39;s location data, including GPS coordinates, which is received at a remote location, such as a command center where rescue efforts are coordinated. The transmitted location data may be used to determine the position of the user relative to the position of colleagues that are also broadcasting location data. The relative positions of the user and colleagues received at a command center may be used to coordinate rescue efforts. The GPS transceiver  280  is also able to receive the location data of colleagues in the vicinity. The GPS transceiver  280  allows the display screen  208  to show the relative position of colleagues that are in the vicinity of the user. 
     The display unit  210 , includes components  278  for wireless network connectivity, so that the AR view (such as  114  of  FIG.  1   ) displayed on the screen  208  and/or the view of the environment  232  captured by the dual camera  254  can be wirelessly transmitted to a remote location, such as a command center, where fire rescue is coordinated. The transmitted view may also be recorded to a media storage device for later viewing. In this way, the recording can be reviewed for analysis of firefighter skill and execution and for training purposes. 
     In the embodiment shown in  FIG.  5   , the GPS transceiver  280  and wireless network components  278  are located within the display unit  210 . According to another embodiment, the GPS transceiver  280  and wireless network components  278  may be located within a processing unit (such as processing unit  274  in  FIGS.  2 ,  3  and  4   ). 
     The display unit  210  includes a first screen shield  264  and a second screen shield  266 . The screen shields  264 ,  266  maintain the position and spacing of components within the display unit  210 . The display unit  210  includes two screen fixers  268 . The screen fixers  268  attach the display screen  208  to the second screen shield  266 . 
     The display unit  210  includes a projection screen  270 . The projection screen projects the AR view (such as  114  of  FIG.  1   ) rendered by the display unit  210  onto the display screen  208 . The AR view projected by the projection screen  270  is inverted, so that the reflection on the display screen  208  as seen by the user is oriented correctly. 
     The display unit  210  includes an attachment mount  282  for attaching additional accessories (not shown). Additional accessories may include an identification badge or crest normally placed on the front of the headgear  203 . 
     Referring again to  FIGS.  2 ,  3  and  4   , the display system  200  includes a processing unit  274  attached to the helmet  203 . The attachment of the processing unit  274  to the helmet  203  can be done by adhesive for a permanent attachment or attachment by Velcro or tensile straps for a removable attachment. The processing unit  274  is in connection with the display unit  210  of the AR display  206 . The processing unit  274  contains a rechargeable battery pack (not shown) for powering the display system  200 . The processing unit  274  is positioned on the helmet brim  204  opposite the AR display  206 . This configuration allows the processing unit  274  to counterbalance the weight of the AR display  206  and mounting assembly  212  so that the helmet  203  remains stably positioned on the user&#39;s head when the display system  200  is attached to the helmet  203 . 
     The processing unit  274  includes an image processing system  260 . The image processing system  260  is coupled to components within the display unit  210  (including thermal camera  248 , dual camera  254 , projection screen  270 , GPS transceiver  280  and wireless network components  278  of  FIG.  5   ). The processing system  260  receives the view of the environment  232  captured by a thermal camera (such as thermal camera  248  of  FIG.  5   ), renders an AR view (such as AR view  114  of  FIG.  1   ) of the environment  232  and outputs the AR view to a display screen (such as display screen  208  in  FIGS.  2 ,  4  and  5   ). 
     Referring to  FIG.  6   , illustrated therein is a diagram of an image processing system  300 , in accordance with an embodiment. The processing system  300  may be the image processing system  260  contained within the processing unit  274  of  FIGS.  2 ,  3  and  4   . The processing system  300  includes a processor  302  having a plurality of modules. 
     The processing system  300  also includes a memory  304  having a plurality of memory units. The processor  302  is in communication with the memory  304 . 
     The processing system  300  is connected to a thermal imaging camera  306 , such as thermal camera  248  of  FIG.  5   . The camera  306  captures a view of the environment  310 . The camera  306  captures the view  310  as a plurality of frames  308 . Each frame  308  captured by the camera  306  is sent to the processor  302 . Each frame  308  received by the processor  302  begins an iteration of the processing system  300 . 
     The processor  302  includes a capture module  312 . The capture module  312  receives each frame  308  from the camera  306 . For each frame  308 , the capture module  312  obtains a thermal value  316  for each pixel location  314  in the frame  308 . The pixel location  314  and corresponding thermal value  316  obtained by the capture module  312  are sent to the memory  304 . The memory  304  stores the pixel locations  314  and thermal values  316  together as a “thermal view”  318  of the frame  308 . The thermal view  318  includes the thermal value  316  for each pixel location  314  in the frame  308 . The thermal view  318  is retained in the memory  304 , until the system  300  completes an iteration and the next frame  308  is received by the capture module  312 . 
     The processor  302  includes an edge detection module  322 . The edge detection module  322  retrieves the thermal view  318  from the memory  304 . The edge detection module  322  locates edges  326  in the thermal view  318 . The edges  326  are indicative of objects (such as object  272  of  FIG.  2   ) in the view of the environment  310  captured in the frame  308 . The edges  326  found by the edge detection module  322  are sent to the memory  304 . The edges  326  are retained in the memory  304  until the system  300  completes the iteration and the next frame  308  is received by the capture module  312 . 
     The processor  302  includes a virtual view module  330 . The virtual view module  330  retrieves the edges  326  from the memory  304 . The virtual view module  330  renders a “virtual view”  332  of the frame  308 . The virtual view  332  includes only the edges  326 . Pixel locations  314  not deemed to be edges  326  by the edge detection module  322  are omitted from the virtual view  332 . The virtual view  332  rendered by the virtual view module  330  is sent to the memory  304 . The virtual view  332  is retained in the memory  304  until the system  300  completes the iteration and the next frame  308  is received by the capture module  312 . 
     The processor  302  includes an overlay module  334 . The overlay module  334  retrieves the thermal view  318  and the edges  326  from the memory  304 . The overlay module  334  overlays the edges  326  onto the thermal view  318  to render a “fusion view”  342  of the frame  308 . The fusion view  342  includes the edges  326 , the pixel locations  314  and thermal values  316  (taken from the thermal view  318 ). The fusion view  342  rendered by the overlay module  334  is sent to the memory  304 . The memory  304  retains the fusion view  342  until the system  300  completes the iteration and the next frame  308  is received by the capture module  312 . 
     The processor  302  includes an object identification module  344 . The object identification module  344  retrieves the fusion view  342  from the memory  304 . The object identification module  344  identifies objects  346  in the fusion view  342 . The objects  346  are pixel locations  314  in the fusion view  342  that are wholly enclosed by edges  326 . Wholly enclosed means pixel locations  314  that are surrounded by an unbroken ring of edges  326 . A plurality of adjacent pixel locations  314  may be wholly enclosed by edges  326 . The objects  346  identified by the object identification module  344  are sent to the memory  304 . The memory  304  retains the objects  346  until the system  300  completes the iteration and the next frame  308  is received by the capture module  312 . 
     The processor  302  includes a measurement module  350 . The measurement module  350  retrieves the thermal view  318  and objects  346  from the memory  304 . The measurement module  350  obtains the thermal value  316  (taken from the thermal view  318 ) for each object  346 . For a plurality of adjacent pixel locations  314  corresponding to an object  346 , the measurement module  350  calculates an object thermal value  352 . The object thermal value  352  is the average of the thermal values  316  for the pixel locations  314  corresponding to the object  346 . The object thermal values  352  calculated by the measurement module  350  are sent to the memory  304 . The memory  304  retains the object thermal values  352  until the system  300  completes the iteration and the next frame  308  is received by the capture module  312 . 
     The processor  302  includes a comparison module  354 . The comparison module  354  is programmed with a pre-calibrated thermal value  356  for human body temperature. The comparison module  354  retrieves the objects  346  object thermal values  352  and pixel locations  314  from the memory  304 . The comparison module  354  compares the object thermal value  352  of each object  346  against the pre-calibrated value  356 . If the object thermal value  352  for the object  346  accords with the pre-calibrated value  356 , the object  346  is deemed to have human temperature. The objects  356  deemed as having human temperature, along with the corresponding object pixel locations  314  are sent to the memory  304 . The memory stores the objects  346  as human temperature objects  358  and the corresponding pixel locations  314  as human temp pixel locations  360 . The memory  304  retains the human temperature objects  358  and the human temperature pixel locations  360  until the system  300  completes the iteration and the next frame  308  is received by the capture module  312 . 
     The processor  302  includes a highlighting module  362 . The highlighting module  362  retrieves the thermal values  316 , the edges  326  and the human temperature pixel locations  360  from the memory  304 . The highlighting module  362  renders a “highlighted view”  364  of the frame  308 . The highlighted view  364  includes the edges  326  and the thermal values  316  for the human temperature pixel locations  360 . The highlighted view  364  is sent to the memory  304 . The memory  304  retains the highlighted view  364  until the system  300  completes the iteration and the next frame  308  is received by the capture module  312 . 
     The processor  302  includes a display module  366 . The display module  366  retrieves the highlighted view  364  from the memory  304 . The display module  366  is coupled to a display screen  368 . The display module  366  outputs the highlighted view  364  to the display screen  368 . Once the highlighted view  364  is output to the display screen  368 , the iteration of the processing system  300  is complete and the capture module  312  receives the next frame  308  from the camera  306 . Optionally, the user can choose to output the thermal view  318  or the virtual view  332  to the display screen  368  in accordance with an embodiment. The display module  366  retrieves the thermal view  318  or virtual view  332  from the memory  304  for output to the display screen  368 . 
     The time taken for a single iteration of the system  300  should be less than the inverse of the frame rate of the thermal imaging camera  306 . For example, if the camera  306  captures the view of the environment  310  at 30 frames per second, a single iteration of the processing system  300  should not exceed 1/30 seconds. This allows for the processing system  300  to receive each frame  308  and output the highlighted view  364  in real time. 
     Disclosed herein is a mounting assembly for attaching a display screen to headgear. The mounting assembly can be used with a variety of headgear types and sizes. The mounting assembly allows for a display screen to be positioned in front of the user&#39;s eyes, and on the outside of a SCBA mask worn by the user. 
     Referring to  FIG.  7    illustrated therein are the components of a mounting assembly  400  shown attaching to headgear  402  in accordance with an embodiment. The headgear  402  is a firefighter helmet  404 , and includes a brim  406 . 
     The mounting assembly  400  includes at least one connector  408  for reversibly attaching the mounting assembly to the helmet brim  406 . The connector  408  is U-shaped, having a proximate end  410 , a distal end  412 , and flanges  414 ,  416  that form a groove  418 . For attachment, the groove  418  contacts the helmet brim  406  for attachment, so that the brim  406  is interposed between the flanges  414 ,  416  of the connector  408 . Ideally, the helmet brim  406  should extend into the groove  418  up to the depth of the flanges  414 ,  416  to allow for even weight distribution of the assembly  400  across the helmet brim  406 . The connector  408  includes two locking members  420   a ,  420   b.    
     Referring to  FIG.  8   , illustrated therein is a close up view of the connector  408  and locking members  420   a ,  420   b  of  FIG.  7   . The connector  408  has a first recess  422  in the flange  416  for receiving locking member  420   a . The connector  408  has a second recess  424  in the flange  414  for receiving locking member  420   b . The recesses  422 ,  424  are adjacent to the distal end  412  of the connector  408 . The locking members  420   a ,  420   b  each have opposable ends  440  and  442 , an opening  444 , a jaw  446  and a pivot arm  448 . The opening  444  passes between the ends  440 ,  442  of each locking member  420   a ,  420   b . Each locking member  420   a ,  420   b  is permanently attached to the connector  408  by a locking pin  452 . Each locking pin  452  passes through the locking members  420   a ,  420   b  via the opening  444  and protrudes from both ends  440 ,  442 . The recesses,  422 ,  424  each have two dimples  450  to receive the locking pin  452  protruding from each end  440 ,  442  of the locking members  420   a ,  420   b.    
     Still referring to  FIG.  8   , the locking members  420   a ,  420   b  are pivotable about the locking pin  452 . The locking members  420   a ,  420   b  pivot between two positions. In the first position (as shown), the pivot arm  448  is parallel to the flanges  414 ,  416 , and the jaw  446  is perpendicular to the flanges  414 ,  416  and extends into the groove  418 . The jaw  446 , of each locking member  420   a ,  420   b  are opposable and act together to reversibly clamp the connector  408  to a helmet brim (such as brim  406  of  FIG.  7   ). The brim is held between the jaw  446  of each locking member  420   a ,  420   b  within the groove  418 . Attachment of the connector  408  to the helmet brim is maintained by the frictional force of the jaw  446  on the helmet brim. In the second position (not shown), the pivot arm  448  is perpendicular to the flanges  414 ,  416  and the jaw  446  is parallel to the flanges  414 ,  416  so that the jaw  446  does not contact the helmet brim allowing for detachment of the connecter  408  from the brim. The locking members  420   a ,  420   b  are transitioned between the first and second position by the user exerting force on the pivot arm  448 . The use of clamping means for attaching the connector  408  to the brim allows for quick installation and removal of the connector (and the entire mounting assembly  400  of  FIG.  7   ) by hand without the need for any specialized tools. It is also possible for the user to remove the mounting assembly  400  from the headgear  402 , by hand, without first removing the headgear  402 . 
     Referring again to  FIG.  7   , the connector  408  is attached to a display mount  426 . The display mount  426  includes a support  428 , positioned perpendicular to the helmet brim  406 , for connecting the display mount  426  to a display screen (not shown). The display mount  426  includes a base  430 , positioned parallel to the helmet brim  406 , for attaching the display mount  426  to the connector  408 . The base  430  is attached to the proximate end  410  of the connector  408  by a friction fastener  432  via an aperture  434  in the base  430 . The fastener  432  passes through the aperture  434  in the base  430 , and through an aperture  436  in the flange  416  of the connector  408 . The friction fastener  432  and the aperture  436  may be threaded. Attachment of the display mount  426  to the connector  408  is maintained by frictional force of the fastener  432  on the base  430  of the display mount  426 . 
     The fastener  432  can be driven by hand. This allows for the display mount  426  to be easily attached or removed from the connector  408  without the need for any specialized tools. 
     Referring to  FIG.  9   , illustrated therein is the mounting assembly  400  of  FIG.  7   , shown attached to a helmet  404 . It is preferable to use at least two connectors  408  for attaching the mounting assembly  400  to the helmet  404 . The use of two connectors  408  allows for the position of the mounting assembly  400  to be better fixed on the helmet  404 . Further, the use of two connectors  408  allows for the weight of the mounting assembly  400  (and display screen when attached) to be more evenly distributed across the brim  406  of the helmet  404  than if a single connector is used. 
     The attachment angle  438  formed between the base  430  and the proximate end  410  of the connector  408  can be any obtuse angle, allowing for the mounting assembly  400  to be attached to helmet brims with varying size and curvature. Ideally, both angles  438  should be equal to allow for the weight of the mounting assembly  400  and display screen (not shown) when attached to be evenly distributed across the area of the brim  406  that is in contact with the connectors  408 . The shape of the aperture  434  in the base  430  allow for the fastener  432  to attach the base  430  to the connector  408  at various points more proximate or distal to the center of the base  430 , further increasing the compatibility of the mounting assembly  400  with different helmet types. A user can vary the attachment angels  438  and point of attachment between the connectors  108  and the base  430  of the display mount  412  to determine the optimal parameters for attachment to a given helmet type. 
     Referring to  FIG.  10   , illustrated therein is a flow chart of a method  600 , in accordance with an embodiment, for firefighters and first responders to locate and identify people in a burning building where low light, dust, smoke and debris can obscure the first responder&#39;s view of the surroundings. The method  600  includes thermal imaging and edge detection image processing to provide an augmented reality view of the user&#39;s environment by highlighting human temperature objects in the field of view, allowing for quick identification and location of persons obscured by poor visibility. 
     The method  600  includes capturing a thermal view of the environment to be augmented ( 602 ).  602  may be accomplished using the thermal imaging camera  248  of  FIG.  5    or the thermal imaging camera  306  of  FIG.  6   . 
     Referring to  FIG.  11   , shown therein is an exemplary thermal view  700  of  602 . The thermal view  700  corresponds to a single frame  308  in  FIG.  6   . The thermal view  700  consists of the pixel locations  314  and thermal values  316  making up the thermal view  318  of  FIG.  6   . The thermal view  700  shows the environment  712  according to thermal values (i.e. thermal values  316 ). Thermal values are represented in the thermal view  700  as brightness. Objects  702 ,  704 ,  706 ,  708  are at higher temperature, have a higher thermal value, and appear brighter. Object  710  is at a lower temperature, has a lower thermal value, and appears darker. The ambient temperature of the environment  712  is room temperature. Thus, the objects having a temperature higher than room temperature (a human  702 , a computer  704 , a monitor  706  and lights  708 ) appear brighter. The objects at (or below) room temperature (a desk  710 ) appear darker. A user viewing the thermal view  700  is able to distinguish warmer objects (the human  702 , the computer  704 , the monitor  706  and the lights  708 ) from cooler objects (the desk  710 ) based on the object&#39;s brightness in the thermal view  700 . 
     In a burning building, the ambient temperature can rise, causing objects in the environment to increase in temperature. The increase in temperature causes the objects in the environment to have a higher thermal value and appear brighter in the thermal view than they would appear at room temperature. Consequently, a thermal view of a high temperature environment may become saturated, and individual objects in the thermal view may not be easily distinguishable by eye. To account for this, the method  600  may, optionally, comprise a thermal view that is corrected for the ambient temperature in the environment ( 604 ).  604  is achieved by uniformly reducing the thermal values (brightness) in the thermal view  700  by a factor corresponding to the ambient temperature in the environment. Alternatively, the correction of  604  may comprise increasing the contrast in the thermal view  700  so that warmer objects in the environment may be more easily distinguished from cooler objects. 
     The method  600  includes creating a virtual view of the objects in the environment according to the edges detected in the thermal view ( 608 ).  608  may be accomplished by concerted action of the edge detection module  322  and the virtual view module  330  of  FIG.  6   . 
     Referring to  FIG.  12   , shown therein is an exemplary virtual view  800  of  608 . The virtual view  800  corresponds to the virtual view  332  of  FIG.  6   . The virtual view  800  shows the delineated edges of objects  802 ,  804 ,  806 ,  808 ,  810  in the environment  812  that are captured in the thermal view  700 . A user seeing the virtual view  800  is able to glean the presence of an object in the environment  812  by seeing its edge(s) in the virtual view  800 . As such, the virtual view  800  of the environment can be used to identify objects or obstacles in the environment  812  based on the presence of its edge(s) in the virtual view  800 . 
     The human  702 , the computer  704 , the monitor  706  and the lights  708 , which have a higher thermal value and appear brighter in the thermal view  700 , are delineated completely in the virtual view  800  as the human  802 , the computer  804 , the monitor  806  and the lights  808 . The delineation of objects  802 ,  804 ,  806  and  808  is complete since the outline of objects  802 ,  804 ,  806  and  808  unbroken and the boundaries of  802 ,  804 ,  806  and  808  are clearly defined in the virtual view  800 . 
     The desk  710 , having a lower thermal value and appearing darker in the thermal view  700 , is only partially delineated in the virtual view  800  as desk  810 . The partially delineated desk  710  appears in the virtual view  800  as a “floating” edge  814 . The floating edge  814  does not completely outline the boundary of the desk  810 . A user seeing the virtual view  800  is nonetheless able to glean the presence of the desk  810  in the environment  812  by the existence of floating edge  814 . 
     Referring again to  FIG.  10   , the method  600  includes measuring the thermal value of each completely delineated object (human  802 , computer  804 , monitor  806  and lights  808 ) in the virtual view  800  ( 612 ).  612  may be accomplished by concerted action of the object ID module  344  and measurement module  350  of  FIG.  6   . 
     Still referring to  FIG.  10   , the method  600  includes comparing the measured thermal value for each completely delineated object is against a pre-calibrated value for human body temperature ( 620 ).  620  may be accomplished by the comparison module  354  of  FIG.  6   . If the measured thermal value of the delineated object (ie. object thermal value  352  in  FIG.  6   ) accords with the pre-calibrated value (ie. pre-calibrated value  356  in  FIG.  6   ), the delineated object is identified a human temperature object (ie. human temp object  358  in  FIG.  6   ) ( 614 ). According to another embodiment,  614  may be accomplished by using the pre-calibrated value of  620  as a threshold. Delineated objects with a thermal value equal to or exceeding the pre-calibrated value of  620  are identified as human temperature objects. 
     The method  600  includes highlighting the identified human temperature objects in the fusion view to create a highlighted view ( 616 ).  616  specifically highlights the human temperature objects in the environment, and excludes non-human temperature objects.  616  may be accomplished by the highlighting module  362  of  FIG.  6   . 
     Referring to  FIG.  13   , shown therein is an exemplary highlighted view  900  of  616 . The highlighted view  9800  corresponds to the highlighted view  364  of  FIG.  6   . Human temperature objects in the highlighted view  900  are highlighted by showing the thermal value for the object within the delineated edge(s) of the object. The human temperature objects (the human  902 , the computer  904 , the monitor  906  and the lights  908 ) are seen according to their thermal value and delineated edges. The objects not corresponding to human temperature (the desk  910 ) are shown as a floating edge  914  with no thermal value (appearing black). Thus, the highlighted view  900  allows a user to see all objects  902 ,  904 ,  906 ,  908 ,  910  in the environment  912  according to delineated edges, and specifically see human temperature objects  902 ,  904 ,  906 ,  908  according to thermal values. As such, a user seeing the highlighted view  900  can navigate the non-human temperature objects  910  to hone in on the highlighted human temperature objects  902 ,  904 ,  906 ,  908  in the environment  912 . To differentiate between highlighted objects that are actually human (the human  902 ) and those that are not human (the computer  904 , the monitor  906  and the lights  908 ), the shape and position of the object are determinative. 
     The highlighted view  900  contains a false positive  916 . The false positive  916  appears as a completely delineated object with a thermal value extending beyond the periphery of the highlighted view  900 . A false positive  916  can be the result of a high temperature object (such as human) in close proximity to the thermal camera (i.e. thermal imaging camera  248  of  FIG.  5    or the thermal imaging camera  306  of  FIG.  6   ), at the periphery of the environment  912  and not wholly captured in a single frame of act  602 . 
     The highlighted view  900  contains several artefacts  918 . The artefacts  918  appear as diffuse thermal values with no surrounding delineated edge(s). The artefacts  918  are the result of hot air emanating from hot objects, such as the hot air expelled from computer  904  or monitor  906 . Objects  902 ,  904 ,  906 ,  910  appearing in the highlighted view  900  as completely delineated objects with a thermal value can be regarded with high confidence as actually being present in the environment  912 . With training, a user seeing the highlighted view  900  will be able to identify false positive  916  and artefacts  918  and disregard them from actual objects in the environment  912 . 
     Referring again to  FIG.  10   , method  600  provides that the highlighted view  900  is output to a display screen ( 618 ). The display screen of  618  may be the display screen  368  of  FIG.  6   , or the display screen  208  of  FIGS.  2 ,  4  and  5   . The display screen may be located in a remote location away from the environment the camera is viewing in accordance with an embodiment. 
     The output of  618  may be switched to show the thermal view  700 , the virtual view  800 , or the highlighted view  900  as desired by the user, in accordance with an embodiment. Depending on the environment and situation, a user may find viewing the thermal view  700  or virtual view  800  more advantageous than the highlighted view  900 . For example, the thermal view  700  is useful for identifying large objects/obstacles in the environment that are cooler than human temperature and would therefore not be seen (appear black) in the highlighted view. 
     Turning now to  FIGS.  15  to  19   , another embodiment of an augmented reality display apparatus is shown and is generally indicated by reference numeral  1020 . The augmented reality display apparatus  1020  comprises an augmented reality display device  1022  that is configured to be mounted on a headgear  1024  having a brim  1026  and worn by a user. The augmented reality display device  1022  is configured to display an augmented reality view of the surrounding environment to the user. In the example shown, the headgear  1024  is a firefighter helmet, however it will be understood that the headgear  1024  can be another form of headgear having a brim, such as a military helmet, a construction helmet, a mining helmet, a hat, a cap, and the like. 
     The augmented reality display device  1022  comprises a display unit  1030  and a processing unit  1032  that are connected to each other by an adjustable strap  1034 . The display unit  1030  is configured to be mounted on a forward portion of the headgear  1024  proximate the face of the user, and the processing unit  1032  is configured to be mounted at another position on the headgear  1024 . In particular, the processing unit  1032  is typically positioned at a rearmost position on the headgear  1024 , diametrically opposite the display unit  1030 , to provide balancing of weight of the augmented reality display device  1022  on the headgear  1024 . 
     The length of the adjustable strap  1034  can be varied to enable the augmented reality display device  1022  to be easily fastened and unfastened to headgear of different shapes and sizes. In the example shown, the strap  1034  has a ratcheted buckle configuration, and comprises two (2) first strap portions  1036  connected to the display unit  1030  and each having a releasable buckle  1038  at an end thereof, and a second strap portion  1042  separate from the first strap portions  1036  and connected to the processing unit  1032 . The second strap portion  1042  has an array of teeth  1044  disposed along a surface of each end thereof. As will be understood, each buckle  1038  is configured to receive an end of the second strap portion  1042  and engage the teeth  1044  disposed thereon, to allow the length of the adjustable strap  1034  to be secured at a desired length. After use, one or both buckles  1038  can be released to disengage the teeth  1044 , to allow the augmented reality display device  1022  to be loosened and separated from the headgear  1024 . 
     The display unit  1030  comprises a base  1050  that is shaped to engage the brim  1026  to enable the display unit  1030 , and in turn the augmented reality display device  1022 , to be more securely fastened to the headgear  1024 . In this embodiment, the base  1050  has a pair of rearwardly-extending tabs, namely an upper tab  1052  and a lower tab  1054 , that define a curved groove  1056  therebetween. The groove  1056  is sized and shaped to receive at least a portion of the brim  1026  of the headgear  1024 . The base  1050  also has two (2) upwardly extending tabs  1062 , each having a slot  1064  formed therein through which a looped end of a respective first strap portion  1036  is connected. 
     The base  1050  has a forward upper portion that supports a thermal camera  1070 , a toggle switch  1072 , and a rotary switch  1074 . The thermal camera  1070  may be, for example, a Boson™  320  compact longwave infrared (LWIR) camera manufactured by FLIR Systems Inc., of Wilsonville, Oreg., U.S.A. A removable cover  1076  is disposed on the forward upper portion of the base  1050 , and defines an enclosure in which the thermal camera  1070 , the toggle switch  1072 , and the rotary switch  1074  are at least partially accommodated. The cover  1076  has a forward window  1078  for the thermal camera  1070 , and has apertures through which the toggle switch  1072  and the rotary switch  1074  protrude, to allow each of the switches  1072  and  1074  to be operated by the user. The base  1050  further comprises a scalloped, forwardly-extending tab that is shaped to receive a spacer  1084 . A display screen  1086 , which is fabricated of generally transparent plastic, is mounted to the base  1050  against the spacer  1084 . The display screen  1086  is sized to cover a portion of the face of the user, and specifically the eyes and surrounding area of the face of the user, such that the user&#39;s field of view is covered by the display screen  1086  during use. The base  1050  also comprises a downwardly-inclined tab  1088  that defines a recess sized to accommodate a driver board  1094  and an image projector  1096 . In this embodiment, the driver board  1094  is a field-programmable gate array (FPGA) configured to process an image frame and generate two (2) paired image frames containing partially overlapping image data, and to output the two (2) paired image frames to the image projector  1096 . In this embodiment, the image projector  1096  is a set of two (2) liquid crystal displays (LCDs), and each LCD of the two (2) LCDs of the image projector  1096  is configured to display a respective one (1) of the paired image frames. Each LCD may be, for example, a 1.95 inch 320 (RGB)×480 colour display (model no. ET020HV03-OT) manufactured by Hong Kong Eurotech Electronics Co., Ltd., of Shenzen, China. The image frames displayed by the image projector  1096  in turn illuminate (or in other words, are “projected onto”) the display screen  1086 , where they are reflected and thereby appear within the field of view of the user to create the augmented reality view. 
     Turning now to the processing unit  1032 , the processing unit  1032  comprises a housing  1098  that encloses processing structure  1100 , a digital gyroscope  1102 , a wireless transceiver  1104 , and a battery  1106 . The processing structure  1100  comprises one or more processors (not shown) that are in communication with each other, and which are in communication with memory  1108 , all of which are mounted on or more boards (not shown). The processing structure  1100  may comprise, for example, an ARM™ Cortex-A53 processor designed by Arm Holdings of Cambridge, United Kingdom. The digital gyroscope  1102  is configured to output a digital orientation signal to the processing structure  1100 , which in turn is configured to process the digital orientation signal and to generate a compass heading indicator to be overlaid on one or more image frames. The digital gyroscope may be, for example, a BMI160™ low power inertial measurement unit (IMU) manufactured by Bosch Sensortec GmbH of Reutlingen, Germany. As will be appreciated, such a compass heading indicator can be beneficial in situations where poor visibility can otherwise disorient the user. The wireless transceiver  1104  is configured to wirelessly transmit image frames to a remote location, such as for example a command center for viewing by other parties, and/or or to a remote server for storage, and the like. The wireless transceiver  1104  may be configured to wirelessly communicate using any of Ethernet, Wi-Fi™, Bluetooth™ and the like. The battery  1106  comprises one or more rechargeable cells (not shown), and is configured to power the electronic components of the augmented reality display device  1022 . 
     The processing structure  1100  is in communication with the thermal camera  1070 , the toggle switch  1072 , and the rotary switch  1074 , and the driver board  1094 , via wired communication through a cable  1112  extending between the processing unit  1032  and the display unit  1030 . The cable  1112  enables signals and/or image data to be conveyed from the thermal camera  1070 , the toggle switch  1072 , and the rotary switch  1074  to the processing structure  1100 , and from the processing structure  1100  to the driver board  1094 . The cable  1112  is also configured to supply power to the components of the display unit  1030 . 
     The processing structure  1100  runs an image processing program that effectively provides a plurality of image processing modules, which are similar to those described above for processing system  300  with reference to  FIG.  6   . During operation, the processing structure  1100  continuously receives image data from the thermal camera  1070  as a sequence of captured image frames. The image processing program running on the processing structure  1100  provides a capture module, which processes each image frame received from the thermal camera  1070  to obtain a thermal value for each pixel location. The capture module then stores the thermal values and their pixel locations in memory  1108 , and generates a thermal image frame (referred to herein as a “thermal view”) having a compass heading indicator determined from the signal output by the digital gyroscope  1102  overlaid on the thermal values at their pixel locations. The “thermal view” is stored in memory  1108  until the next captured image frame is received by the capture module. 
     The image processing program running on the processing structure  1100  provides an edge detection module, which is configured to retrieve the thermal view from memory  1108 , and to process the thermal view to identify edges of objects appearing in the image by using a two-dimensional Laplacian filter. The edge detection module then stores the pixel locations corresponding to the edges as edge data in the memory  1108 , until the next captured image frame is received by the capture module. 
     The image processing program running on the processing structure  1100  provides a virtual view module, which is configured to retrieve the edge data from the memory  1108 , and to generate an edge image frame comprising only the edge data (and a compass heading indicator determined from the signal output by the digital gyroscope  1102  overlaid thereon), referred to herein as a “virtual view”. As will be understood, the “virtual view” is a representation of only the identified edges of objects, and therefore pixel locations not deemed to be edges by the edge detection module appear as dark in the “virtual view”. Each “virtual view” is stored in memory  1108 , until the next captured image frame is received by the capture module. 
     The image processing program running on the processing structure  1100  provides an overlay module, which is configured to retrieve the thermal view and the edge data from the memory  1108 , and to overlay the edge data on the “thermal view” to produce a combined thermal image frame including edges (with a compass heading indicator determined from the signal output by the digital gyroscope  1102  overlaid thereon), referred to herein as a “fusion view”. As will be understood, the “fusion view” includes edges overlaid on the thermal image data represented by the thermal value at each pixel location. Each “fusion view” is stored in memory  1108  until the next captured image frame is received by the capture module. 
     The image processing program running on the processing structure  1100  provides an overlay module, which is configured to retrieve the “fusion view” from memory  1108  and to process the “fusion view” to identify objects appearing in the image. In particular, the overlay module identifies objects by finding groups of pixels that are surrounded by an unbroken (i.e. continuous) perimeter of edges. The pixel locations corresponding to the objects identified by the edge detection module are stored as object data in the memory  1108 , and are retained until the next captured image frame is received by the capture module. 
     The image processing program running on the processing structure  1100  provides a measurement module, which is configured to retrieve the “thermal view” and the object data from the memory  1108 . The measurement module determines an object thermal value for each object defined in the object data, by calculating the mean of the thermal values for the pixel locations associated with that object. The object thermal values and their pixel locations are stored in the memory  1108  as object thermal value data, where they are retained until the next captured image frame is received by the capture module. 
     The image processing program running on the processing structure  1100  provides a comparison module  354 , which is configured to store a threshold intensity value in memory  1108 . Upon receiving input from the rotary switch  1074 , the comparison module either increases or decreases the threshold intensity value in accordance with the input, and stores the adjusted threshold intensity value in memory  1108  as the threshold intensity value. As will be appreciated, the user may desire to adjust the threshold intensity value through operation of the rotary switch  1074  to set the threshold intensity value to correspond to human body temperature, for example, or to another temperature of significance. The comparison module is also configured to retrieve the object thermal value data from the memory  1108 , and compare each object thermal value to the threshold value. If the object thermal value for an object is equal or substantially equal to the threshold value, the object is deemed to be a threshold temperature object. The comparison module stores the pixel locations associated with each threshold temperature object as threshold temperature object data in memory  1108 , until the next captured image frame is received by the capture module. 
     The image processing program running on the processing structure  1100  provides a highlighting module, which is configured to retrieve the object thermal values, the edge data and threshold temperature object data from the memory  1108 , and to overlay the edge data and the object thermal value data at pixel locations associated with each threshold temperature object, to produce a threshold object thermal image frame including edges (and with a compass heading indicator determined from the signal output by the digital gyroscope  1102  overlaid thereon), referred to herein as a “highlighted view”. Each “highlighted view” is stored in memory  1108  until the next captured image frame is received by the capture module. 
     The image processing program running on the processing structure  1100  also provides a display module, which is configured to store a display mode value in memory  1108 . In this embodiment, the available display mode values are virtual view, fusion view, and highlighted view, which are stored as a repeating sequence. Upon receiving input from the toggle switch  1072 , the comparison module cycles to the next display mode value in the sequence, and stores the updated display mode value in memory  1108  as the display mode value. Additionally, the display module is configured to output the image frame associated with the current display mode value to the driver board  1094 . 
     Upon receiving the image frame, the driver board  1094  processes the image frame into two (2) paired image frames containing partially overlapping image data, and outputs the two (2) paired image frames to the image projector  1096 . The image projector  1096  then displays the two (2) paired image frames, with each LCD displaying a respective one (1) of the paired image frames. The image frames displayed by the image projector  1096  in turn illuminate (or in other words, are “projected onto”) the display screen  1086 , where they are reflected and thereby appear within the field of view of the user to create the augmented reality view. 
     In other embodiments, the augmented reality display device may be differently configured. For example, although in the embodiment described above, the thermal camera  1070 , the driver board  1094 , the image projector  1096  and the display screen  1086  are fixedly mounted on the base  1050 , and therefore are fixedly mounted relative to the at least one feature of the processing unit  1030  engaging the headgear  1024  (namely, the upper tab  1052  and the lower tab  1054 , which define the curved groove  1056  that receives at least a portion of the brim  1026 ), in other embodiments, other configurations are possible. For example, in other embodiments, the display screen may be translatably moveable relative to a base comprising upper and lower tabs defining a groove for receiving a portion of the brim, via a translatably moveable assembly, such as for example an assembly similar to display mount  216  and parallel arms  218  described above and with reference to  FIGS.  2  and  4   . In one such embodiment, the thermal camera, the driver board, the image projector and the display screen are all translatably connected relative to a base (comprising upper and lower tabs defining a groove for receiving a portion of the brim) via a linkage arm assembly. In a related embodiment, the translatably moveable assembly may comprise a four-bar linkage. It will be appreciated that in such embodiments, the augmented reality device or apparatus is compatible with a SCBA mask worn by the user, whereby the translatable connection allows at least the display screen to be moved into and out of position to accommodate the SCBA mask. In one such embodiment, the translatable connection allows the thermal camera, the driver board, the image projector and the display screen to all be moved into and out of position in unison to accommodate the SCBA mask. 
     Although in the embodiment described above, the strap  1034  comprises two (2) first strap portions  1036  and a second strap portion  1042  that are configured to be connected to each other by buckles, in other embodiments, the strap may be differently configured. For example, the strap may comprise a single first strap portion, or more than two second strap portions, or only a single portion. Rather than having a ratcheted buckle configuration, one or more ends of the strap may alternatively be fastenable by one or more clips; one or more hooks; one or more belt buckles; one or more hook-and-loop connectors, and the like. The strap may be fabricated of a resilient and/or stretchable material. In one such embodiment, the strap fabricated of the resilient and/or stretchable material may alternatively comprise no fasteners. 
     Although in the embodiment described above, the base  1050  has two (2) upwardly extending tabs  1062 , each having a slot  1064  formed therein through which a looped end of a respective first strap portion  1036  is connected, in other embodiments, the strap may alternatively comprise only a single forward portion and the base may alternatively have only a single tab having only one slot through which the forward portion of the strap is accommodated. Still other connection configurations between the strap(s) and base are possible. 
     The display unit  1030  comprises a base  1050  that is shaped to engage the brim  1026  to enable the display unit  1030 , and in turn the augmented reality display device  1022 , to be more securely fastened to the headgear  1024 . In this embodiment, the base  1050  has a pair of rearwardly-extending tabs, namely an upper tab  1052  and a lower tab  1054 , that define a curved groove  1056  therebetween. The groove  1056  is sized and shaped to receive at least a portion of the brim  1026  of the headgear  1024 . The base  1050  also has two (2) upwardly extending tabs  1062 , each having a slot  1064  formed therein through which a looped end of a respective first strap portion  1036  is connected. 
     Although in the embodiment described above, the cable  1112  is shown as being separate from the adjustable strap  1034 , in other embodiments, the strap and cable may be configured such that the strap is hollow along at least a portion of its length, and the cable is incorporated within the hollow portion of the strap. 
     Although in the embodiment described above, the augmented reality display device  1022  does not comprise a GPS transceiver, in other embodiments, the augmented reality display device may alternatively comprise a GPS transceiver located within the processing unit, with the GPS transceiver having similar or identical function to GPS transceiver  280  described above and with reference to  FIGS.  2  and  4   . 
     Although embodiments have been described above with reference to the accompanying drawings, those of skill in the art will appreciate that variations and modifications may be made without departing from the scope thereof as defined by the appended claims.