Patent Publication Number: US-2017349007-A1

Title: Optical-based tread depth measuring device, system, and method

Description:
BACKGROUND 
     As a vehicle, such as an automobile (including a truck, a bus, and the like), is driven, its tires may begin to wear. As a result, a vehicle operator may need to either periodically check or continuously monitor for tire wear to determine when it may be appropriate to replace worn tires. Tire wear may be checked by a person using a ruler or similar measuring device while standing near a tire of a stationary vehicle. However, some operators may simply forget to check tire wear, or may simply find it too inconvenient, and in either event, do not check wear. 
     It may be desirable to check or monitor one or more tires on a vehicle for tire wear while the vehicle operator remains in the vehicle. It may be desirable to check or monitor for tire wear while the vehicle is in operation, such as when the vehicle is moving. What is needed is a device, system, and method to automatically and/or conveniently check tire wear. 
     SUMMARY 
     In one embodiment, a tire tread depth measuring device may have: at least one camera configured to capture images of a tire tread surface, and at least one processor operatively connected to the camera, wherein the processor is configured to receive, interpret, and transmit a signal from the camera and determine a depth measurement of the tire tread surface. The camera may be at least one of: a digital camera, a video camera, a thermographic camera, an ultraviolet camera, and a radiographic camera. Two cameras may be configured to capture stereographic images. The tire tread depth measuring device may have at least one of: a wireless transmitter, a wireless receiver, and a wireless transceiver. The processor and the camera may be operatively interconnected by at least one of: a wire, a circuit trace, and a wireless transmission. The camera and the processor may be operatively connected to a vehicle. At least one of the camera and the processor may be operatively connected to the vehicle by at least one of: a bolt, a screw, a nut, a bracket, a hook, a weld, a magnet, and an adhesive. 
     In one embodiment, a tire tread depth measuring system may have: a vehicle having an onboard computer; at least one tire having a tread surface, wherein the at least one tire may be mounted to the vehicle; at least one camera, wherein the at least one camera may be oriented to have an unobstructed line of sight to the tire tread surface; and at least one processor operatively connected to at least one of the camera and the onboard computer, wherein the processor may be configured to receive and interpret a signal from the camera, determine a depth measurement of the tread surface, and transmit the depth measurement to the onboard computer. The tire tread depth measuring system may have a camera protection device, wherein the camera protection device may be configured to at least one of clean and protect the camera, wherein the camera protection device may have at least one of: a shield, a cover, a wiper, a screen, a film, a fluid, a reservoir, a pressurization device, and a nozzle. The camera may be at least one of: a digital camera, a video camera, a thermographic camera, an ultraviolet camera, and a radiographic camera. Two cameras may be configured to capture stereographic images. The tire tread depth measuring system may have at least one of: a wireless transmitter, a wireless receiver, and a wireless transceiver. At least one of the camera, the processor, and the onboard computer may be operatively interconnected by at least one of: a wire, a circuit trace, and a wireless transmission. At least one of the camera and the processor may be operatively connected to a vehicle. At least one of the camera and the processor may be operatively connected to the vehicle by at least one of: a bolt, a screw, a nut, a bracket, a hook, a weld, a magnet, and an adhesive. 
     In one embodiment, a tire tread depth measuring method may include: capturing at least one image of a tread surface, determining from the image at least two reference tread surface points, wherein at least one of the reference tread surface points may be oriented on a high tread portion, wherein at least one of the reference tread surface points may be oriented on a low tread portion, and measuring a difference in tread depth between the reference tread surface points. The tire tread depth measuring method may be performed on either a stationary vehicle or a moving vehicle. The tire tread depth measuring method may be initiated either manually by a vehicle operator or automatically by at least one of: a camera, a processor, and an onboard vehicle computer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying figures, which are incorporated in and constitute a part of the specification, illustrate various example devices, systems, and methods, and are used merely to illustrate various example embodiments. In the figures, like elements bear like reference numerals. 
         FIG. 1A  illustrates an elevation view of an example arrangement of an optical-based tread depth measuring device and system. 
         FIG. 1B  illustrates a sectional view of an example arrangement of an optical-based tread depth measuring device and system. 
         FIG. 1C  illustrates a sectional view of an example arrangement of an optical-based tread depth measuring device and system. 
         FIG. 1D  illustrates a schematic of an optical-based tread depth measuring device and system. 
         FIG. 2  illustrates an elevation view of an example arrangement of an optical-based tread depth measuring device and system. 
         FIG. 3  illustrates an elevation view of an example arrangement of an optical-based tread depth measuring device and system. 
         FIG. 4  illustrates an elevation view of an example arrangement of an optical-based tread depth measuring device and system. 
         FIG. 5A  illustrates an elevation view of an example arrangement of an optical-based tread depth measuring device and system. 
         FIG. 5B  illustrates a sectional view of an example arrangement of an optical-based tread depth measuring device and system. 
         FIG. 6  illustrates an elevation view of an example arrangement of an optical-based tread depth measuring device and system. 
         FIG. 7A  illustrates a perspective view of an example arrangement of a tire. 
         FIG. 7B  illustrates a perspective view of an example arrangement of a tire. 
         FIG. 7C  illustrates a perspective view of an example arrangement of a tire. 
         FIG. 8  illustrates a diagram of an optical-based tread depth measuring method. 
     
    
    
     DETAILED DESCRIPTION 
     With reference to  FIGS. 1A-1D , an optical-based tread depth measuring device  100  may be installed on a vehicle  160 . Vehicle  160  may be a road vehicle, such as a passenger car, a tractor-trailer, a bus, and the like. Vehicle  160  may be an off-the-road vehicle. Vehicle  160  may be an agricultural vehicle. Vehicle  160  may be any vehicle with at least one tire  175 . Tread depth measuring device  100  may be a system having one or more components configured to optically measure the tread depth of tire  175 . Tire  175  may be a pneumatic tire. Tire  175  may be a non-pneumatic tire. Tire  175  may be a non-directional tire, wherein tire  175  is configured to be mounted on a vehicle without a specified forward rolling direction. Tire  175  may be a uni-directional tire, wherein tire  175  is configured to be mounted on a vehicle with a specified forward rolling direction. 
       FIGS. 1A-1D  collectively illustrate an example arrangement of optical-based tread depth measuring device and system  100 .  FIG. 1A  is an elevation view of a tread depth measuring device and system  100 .  FIG. 1B  is a sectional view of tread depth measuring device and system  100 .  FIG. 1C  is a sectional view of tread depth measuring device and system  100 .  FIG. 1D  is a schematic of tread depth measuring device and system  100 . Tread depth measuring device and system  100  may have at least one camera  110 . Camera  110  may be at least one of a variety of cameras, such as a digital camera, a video camera, a thermographic camera, an ultraviolet camera, a radiographic camera, and the like. Camera  110  may be operatively connected to vehicle  160  near tire  175 . Camera  110  may be operatively connected to vehicle  160  by at least one of a bolt, a screw, a nut, a bracket, a hook, a weld, a magnet, an adhesive, and the like. Camera  110  may be operatively connected to vehicle  160  such that camera  110  maintains an unobstructed line of sight to tire  175 . Camera  110  may be operatively connected to vehicle  160  at any location on the vehicle that provides an unobstructed line of sight to tire  175 , such as a wheel well, a wheel arch, an inner fender, and the like. Camera  110  may be operatively connected to vehicle  160  such that camera  110  maintains an unobstructed line of sight to tire  175  at any angle relative to tire  175 . Camera  110  may be configured to capture images of a tread of tire  175  having at least one high tread portion  180  and at least one low tread portion  185 . Camera  110  may be configured to transmit a signal of captured images. 
     Tread depth measuring device and system  100  may have at least one processor  130 . Processor  130  may be operatively connected to camera  110 . Processor  130  may be operatively connected to camera  110  by at least one of a wire, a circuit trace, and a wireless transmission. Processor  130  may be operatively connected to vehicle  160 . Processor  130  may be operatively connected to vehicle  160  by at least one of a bolt, a screw, a nut, a bracket, a hook, a weld, a magnet, an adhesive, and the like. Processor  130  may be configured to receive a signal from camera  110 . Processor  130  may be configured to interpret a signal from camera  110 . Processor  130  may interpret a signal from camera  110  by comparing at least two images of high tread portion  180  and low tread portion  185  to determine a tread depth measurement. 
     Tire tread depth measuring system  100  may have two cameras  110 . Having two cameras may allow processor  130  to utilize principles of stereo vision to determine the tread depth measurement of tire  175 . Stereo vision may allow the same feature of tire  175 , such as high tread portion  180  or low tread portion  185 , to be identified by both cameras  110 . By identifying the location of the same feature of tire  175  in the frame of both cameras  110 , a line may be defined from each camera  110  to the feature along a known axis. The intersection of each of the two lines may be mathematically calculated by processor  130 . A calibration process may be performed by processor  130  upon at least one of an installation, an initiation, a configuration, and the like, of tread depth measuring device and system  100 , so that both the distance between, and the relative orientation of, cameras  110  may be known. The intersection of the two lines may occur only at a single fixed distance away from cameras  110 . Processor  130  subtracting the difference between the single fixed distance to high tread portion  180  and the single fixed distance to low tread portion  185  may define the tread depth of tire  175 . Processor  130  may be configured to transmit a signal of tire tread depth measurements. 
     Tread depth measuring system  100  may include an onboard computer  145 . Onboard computer  145  may be operatively connected to vehicle  160 . Onboard computer  145  may be operatively connected to vehicle  160  by at least one of a bolt, a screw, a nut, a bracket, a hook, a weld, a magnet, an adhesive, and the like. Onboard computer  145  may be a vehicle  160 &#39;s onboard computer. Onboard computer  145  may be operatively interconnected with at least one of camera  110  and processor  130 . Onboard computer  145  may be operatively interconnected with at least one of camera  110  and processor  130  by at least one of a wire, a circuit trace, and a wireless transmission. Onboard computer  145  may be configured to receive a signal from processor  130 . Onboard computer  145  may be configured to monitor the tread depth measurement and at least one of: store the tread depth measurement as data, transmit the tread depth measurement to a display device, transmit a message or warning to a vehicle operator, and modify vehicle  160 &#39;s operating conditions. 
     Tread depth measuring system  100  may have at least one wireless communication device (not shown). The wireless communication device may be one of a wireless transmitter (not shown), a wireless receiver (not shown), and a wireless transceiver (not shown). The wireless communication devices may be discrete devices operatively interconnected with at least one of camera  110 , processor  130 , and onboard computer  145 . These wireless devices may be integrated into at least one of camera  110 , processor  130 , and an onboard computer  145 . 
     It is contemplated that at least one of the functions and the structures of camera  110 , processor  130 , and onboard computer  145  may be either discrete or integrated relative to each other. For example, camera  110  and processor  130  may be separate components in both function and structure. However, camera  110  and processor  130  may be integrated such that a single component integrates at least one of the function and the structure of camera  110  and processor  130 . In another example, processor  130  and onboard computer  145  may be separate components in both function and structure. However, processor  130  and onboard computer  145  may be integrated such that a single component integrates at least one of the function and the structure of processor  130  and onboard computer  145 . 
     Tread depth measuring device and system  100  may be configured to measure tread depth while the vehicle is either stationary or moving. Tread depth measuring device and system  100  may be configured to at least one of: measure tread depth intermittently, measure tread depth continuously, be operated manually by a vehicle operator, and be operated automatically by at least one of camera  110 , processor  130 , and onboard computer  145 . Tread depth measuring device and system  100  may be configured to measure tread depth intermittently according to a predetermined schedule based on at least one of: driving time of tire on vehicle and mileage of tire on vehicle. The predetermined schedule may be constant. The predetermined schedule may vary based upon at least one of: road conditions, season of year, age of vehicle, and total mileage of vehicle. 
       FIG. 2  illustrates an example arrangement of an optical-based tread depth measuring device and system  200 . Tire tread depth measuring device and system  200  may have at least one camera  210 . Camera  210  may be operatively connected to a vehicle  260  such that camera  210  maintains an unobstructed line of sight to a tire  275  at a point on tire  275  that is radially tangent to the circumference of tire  275  relative to the position of camera  210 . Tire  275  may have at least one high tread portion  280  and at least one low tread portion  285 . High tread portion  280  may be oriented on the ground contact patch of tire  275 . High tread portion  280  may be oriented on the shoulder portion of tire  275 . High tread portion  280  may be oriented on the crown of tire  275 . Low tread portion  285  may be oriented on the ground contact patch of tire  275 . Low tread portion  285  may be oriented on the shoulder portion of tire  275 . Low tread portion  285  may be oriented on the crown of tire  275 . Low tread portion  285  may be a straight, circumferential groove (not shown), which may facilitate the processor&#39;s (not shown) recognition of low tread portion  285  when camera  210  is operatively connected to vehicle  260  such that camera  210  maintains an unobstructed line of sight to tire  275  at a point on tire  275  that is tangent to the circumference of tire  275  relative to the position of camera  210 . Low tread portion  285  may be a circumferential groove (not shown). Low tread portion  285  may be a groove base. Low tread portion  285  may be a circumferential groove base. Low tread portion  285  may be an axial groove base. Low tread portion  285  may be a notch base. Low tread portion  285  may be a sipe base. 
       FIG. 3  illustrates an example arrangement of an optical-based tread depth measuring device and system  300 . Tire tread depth measuring device and system  300  may have at least one camera  310 . Camera  310  may be operatively connected to a vehicle  360  such that camera  310  maintains an unobstructed line of sight to a tire  375  at an angle relative to tire  375  that is radially orthogonal to the ground contact patch of tire  375 . Camera  310  may be operatively connected to vehicle  360  such that camera  310  maintains an unobstructed line of sight to tire  375  at any radial angle relative to tire  375 . Tire  375  may have at least one high tread portion  380  and at least one low tread portion  385 . High tread portion  380  may be oriented on the ground contact patch of tire  375 . High tread portion  380  may be oriented on the shoulder portion of tire  375 . High tread portion  380  may be oriented on the crown portion of tire  375 . Low tread portion  385  may be oriented on the ground contact patch of tire  375 . Low tread portion  385  may be oriented on the shoulder portion of tire  375 . Low tread portion  385  may be oriented on the crown of tire  375 . 
       FIG. 4  illustrates an example arrangement of an optical-based tread depth measuring device and system  400 . Tire tread depth measuring device and system  400  may have at least one camera  410 . Camera  410  may be operatively connected to a vehicle  460  such that camera  410  maintains an unobstructed line of sight to a tire  475  at an angle relative to tire  475  that is axially orthogonal to a shoulder portion of tire  475 . Camera  410  may be operatively connected to vehicle  460  such that camera  410  maintains an unobstructed line of sight to tire  475  at any axial angle relative to tire  475 . Tire  475  may have at least one high tread portion (not shown) and at least one low tread portion (not shown). The high tread portion may be oriented on the ground contact patch of tire  475 . The high tread portion may be oriented on the shoulder portion of tire  475 . The high tread portion may be oriented on the crown of tire  475 . The low tread portion may be oriented on the ground contact patch of tire  475 . The low tread portion may be oriented on the shoulder portion of tire  475 . The low tread portion may be oriented on the crown of tire  475 . 
       FIGS. 5A-5B  collectively illustrate an example arrangement of an optical-based tread depth measuring device and system  500 .  FIG. 5A  illustrates an elevation view of an example arrangement of an optical-based tread depth measuring device and system  500 .  FIG. 5B  illustrates a sectional view of an example arrangement of an optical-based tread depth measuring device and system  500 . Tire tread depth measuring device and system  500  may have at least one camera  510 . Camera  510  may be operatively connected to a vehicle  560  such that camera  510  maintains an unobstructed line of sight to a tire  575  at an angle relative to tire  575  that is radially orthogonal to the ground contact patch of tire  575 . Camera  510  may be operatively connected to vehicle  560  such that camera  510  maintains an unobstructed line of sight to tire  575  at a point on tire  575  that is radially tangent to the circumference of tire  575  relative to the position of camera  510 . Camera  510  may be operatively connected to vehicle  560  such that camera  510  maintains an unobstructed line of sight to tire  575  at any radial angle relative to tire  575 . Camera  510  may be operatively connected to vehicle  560  such that camera  510  maintains an unobstructed line of sight to tire  575  at an angle relative to tire  575  that is axially orthogonal to a shoulder portion of tire  575 . Camera  510  may be operatively connected to vehicle  560  such that camera  510  maintains an unobstructed line of sight to tire  575  at any axial angle relative to tire  575 . Tire  575  may have at least one high tread portion  580  and at least one low tread portion  585 . High tread portion  580  may be oriented on the ground contact patch of tire  575 . High tread portion  580  may be oriented on the shoulder portion of tire  575 . High tread portion  580  may be oriented on the crown of tire  575 . Low tread portion  585  may be oriented on the ground contact patch of tire  575 . Low tread portion  585  may be oriented on the shoulder portion of tire  575 . Low tread portion  585  may be oriented on the crown of tire  575 . 
       FIG. 6  illustrates an example arrangement of an optical-based tread depth measuring device and system  600 . Tread depth measuring device and system  600  may have at least one camera  610 . Camera  610  may be operatively connected to a vehicle  660  such that camera  610  maintains an unobstructed line of sight to a tire  675  at any angle relative to tire  675 . When vehicle  660  travels along a surface, tire  675  may lift up from the road surface a variety of road contaminants, such as dirt, sand, stones, pebbles, mud, water, and the like. Road contaminants may be deposited on vehicle  660  in the area around tire  675 , such as on wheel wells, wheel arches, inner fenders, and the like. Due to camera  610 &#39;s close proximity to tire  675 , road contaminants may be deposited on camera  610 , resulting in a partially or fully obstructed line of sight to tire  675 . Thus, it may be necessary to protect camera  610  from road contaminants. 
     Tire tread depth measuring system  600  may include a camera protection device  615 . Camera protection device  615  may be operatively connected to vehicle  660  such that camera  610  may be protected from road contaminants to sufficiently maintain an unobstructed line of sight to tire  675 . Camera protection device  615  may be a shield oriented between camera  610  and tire  675  or any road contaminants. Camera protection device  615  may be a clear polymer shield or clear glass shield oriented between camera  610  and tire  675  or any road contaminants. 
     Camera protection device  615  may be a cover, door, shutter, and the like oriented between camera  610  and tire  675  or any road contaminants. Camera protection device  615  may be a cover, door, shutter, and the like configured to partially or completely obstruct or seal camera  610  from tire  675  or any road contaminants. Camera protection device  615  may include an electro-mechanical system, which may be in communication with tread depth measuring device or system  600 , and may manipulate the cover, door, or shutter upon activation by either a vehicle operator or tread depth measuring device or system  600 . Such manipulation may be a rotation, translation, and the like so as to remove the cover, door, or shutter from the line of sight between camera  610  and tire  675 . Such manipulation may occur only momentarily for a duration sufficient to allow camera  610  to capture one or more images as required by tread depth measuring device or system  600 . When camera  610  is not capturing an image of tire  675 , the cover, door, or shutter of camera protection device  615  may remain oriented in a position so as to partially or completely obstruct or seal camera  610  from tire  675  or any road contaminants. 
     Camera protection device  615  may be a wiper configured to wipe across a shield or a lens of camera  610  prior to use of camera  610 , so as to ensure that the shield or lens is clean enough to view tire  675  and measure tread depth. 
     Camera protection device  615  may be a screen oriented between camera  610  and tire  675  so as to prevent road contaminants from coming into contact with, or obstructing the line of sight of, camera  610 . 
     Camera protection device  615  may be a film oriented over or near camera  610 . Camera protection device  615  may be a clear polymer film that may be at least one of: removed, replaced, or repositioned so as to remove from camera  610 &#39;s line of sight any road contaminants that may have accumulated on the film of camera protection device  615 . The film may be operatively connected to a roller at each end, such as with a parchment scroll. Camera protection device  615  may include an electro-mechanical system, which may be in communication with tread depth measuring device or system  600 , and may rotate the rollers just prior to capturing an image, so as to present a fresh portion of film to camera  610 . 
     Camera protection device  615  may be at least one of: a fluid, a reservoir, a pressurization device, a hose, a tube, and a nozzle configured to administer a pressurized fluid to a shield or lens of camera  610  so as to remove road contaminants that may have collected on the shield or lens. The fluid of camera protection device  615  may be at least one of: a commercially available automotive windshield washer fluid, water, an ammonia or bleach based solution, or any fluid suitable for removing road contaminants from a shield or a lens. The fluid may be automotive windshield washer fluid from a vehicle&#39;s existing onboard supply of automotive windshield washer fluid. 
     Camera protection device  615  may be a recess into which camera  610  is oriented so as to remove camera  610  from the path of road contaminants while maintaining an unobstructed line of sight to tire  675 . Camera protection device  615  may be a substantial recess, such as an elongated tube, through which camera  610  may capture an image of tire  675 . Camera  610  may be recessed by a distance. This distance may be any distance capable of removing camera  610  from a path of road contaminants. The distance may be between about 1.0 cm and about 20.0 cm. 
     Camera protection device  615  may be any number or combination of devices, such as, without limitation, those devices described above, that may aid in maintaining an unobstructed line of sight between camera  610  and tire  675 . 
     Furthermore, camera  610  may be operatively connected to vehicle  660  at a position that receives a minimal amount of road contaminant deposits. Such a location may include the portion of vehicle  660  near tire  675  that is nearest to the direction of travel.  FIG. 6  illustrates merely a few examples of such locations. 
     With reference to  FIGS. 7A-7C , a tire  775  may include a tread having at least one high tread portion  780 . High tread portion  780  may be a land portion, or more generally, high tread portion  780  may be the radially outermost portion of the tread. High tread portion  780  may be oriented in a ground contact patch of tire  775 . High tread portion  780  may be oriented in a shoulder portion of tire  775 . High tread portion  780  may be oriented in a crown of tire  775 . 
     Tire  775  may include a tread having at least one low tread portion  785 . Low tread portion  785  may be a groove, or more specifically, the radially innermost portion of a groove adjacent to high tread portion  780 . Low tread portion  785  may be a circumferential groove. Low tread portion  785  may be a groove base. Low tread portion  785  may be a circumferential groove base. Low tread portion  785  may be an axial groove base. Low tread portion  785  may be a notch base. Low tread portion  785  may be a sipe base. Low tread portion  785  may be oriented in the ground contact patch of tire  775 . Low tread portion  785  may be oriented in the shoulder portion of tire  775 . Low tread portion  785  may be oriented in crown of tire  775 . As tire  775  rolls along a surface, high tread portion  780  may be abraded away such that high tread portion  780  erodes radially inward toward low tread portion  785 . The radial distance between high tread portion  780  and low tread portion  785  may be referred to as the “tread depth.” 
       FIGS. 7A-7C  collectively illustrate a tread portion of a tire  775 .  FIG. 7A  illustrates the tread of tire  775  as may be seen by a camera (not shown) that is positioned on a vehicle (not shown) so as to maintain an unobstructed line of sight to a point on tire  775  that is radially tangent to the circumference of tire  775  relative to the position of the camera. Tire  775  may have at least one high tread portion  780  and at least one low tread portion  785 , either of which may be located in at least one of a shoulder portion and a ground contact patch of tire  775 . A single camera may capture images of at least one high tread portion  780  and at least one low tread portion  785  when low tread portion  785  is located at the radially innermost point of a straight, circumferential groove as illustrated in  FIG. 7A . More than one camera may be needed if tire  775  does not have any straight, circumferential grooves. A processor may potentially identify the optimal tread surface points for determining a tread depth measurement by generating a profile of tire  775  and identifying the largest difference in depth between nearby points, such as high tread portion  780  and low tread portion  785 . The camera may be selected with an appropriate resolution for use with a particular line of sight based upon the width of the grooves of tire  775 . For example, cameras with higher resolutions may be able to detect narrower grooves than cameras with lower resolutions. 
       FIG. 7B  illustrates the tread of tire  775  as seen by a camera that is positioned on the vehicle so as to maintain an unobstructed line of sight to tire  775  at an angle relative to tire  775  that is radially orthogonal to the ground contact patch of tire  775 . The camera may be positioned such that the line of sight from the camera to tire  775  may form any angle relative to tire  775 . At least one camera may capture images of at least one high tread portion  780  and at least one low tread portion  785 . Two cameras configured for stereo vision may capture images of at least one high tread portion  780  and at least one low tread portion  785 . The processor may potentially identify the optimal tread surface points for determining a tread depth measurement by identifying the largest difference in depth between nearby points, such as high tread portion  780  and low tread portion  785 . 
       FIG. 7C  illustrates the tread of tire  775  as seen by a camera that is positioned on the vehicle so as to maintain an unobstructed line of sight to both the shoulder portion and the ground contact patch of tire  775 . Tire  775  may have at least one high tread portion  780  and at least one low tread portion  785 . The camera may be positioned such that the line of sight from the camera to tire  775  may form any angle relative to tire  775 . At least one camera may capture images of at least one high tread portion  780  and at least one low tread portion  785 . Two cameras configured for stereo vision may capture images of at least one high tread portion  780  and at least one low tread portion  785 . The processor may potentially identify the optimal tread surface points for determining a tread depth measurement by identifying the largest difference in depth between nearby points, such as high tread portion  780  and low tread portion  785 . 
       FIG. 8  illustrates a diagram of an optical-based tread depth measuring method  805 . Tread depth measuring method  805  may be at least one of: initiated, controlled, monitored, or terminated; either manually by a vehicle operator, or automatically by at least one of a camera, a processor, and an onboard computer. Tread depth measuring method  805  may include capturing at least one image of a tread surface (step  825 ). The tread surface image may be captured by at least one camera and may include at least one high tread portion and at least one low tread portion. The image may be captured while a vehicle is either stationary or moving. The image may be transmitted from the camera to a processor. Tread depth measuring method  805  may include determining from the image at least two reference tread surface points (step  850 ). At least one of the reference tread surface points may be oriented on a high tread portion. At least one of the reference tread surface points may be oriented on a low tread portion. Tread depth measuring method  805  may include measuring a difference in tread depth between the reference tread surface points (step  875 ). This difference in tread depth may represent the tread depth measurement. The processor may determine at least one of the reference tread surface points and the tread depth measurement. The processor may transmit the tread depth measurement to the onboard computer. The onboard computer may store the tread depth measurement as data, transmit the tread depth measurement to a display device, transmit a message or warning to a vehicle operator, modify vehicle&#39;s operating conditions, and the like. 
     It is contemplated that any of the optical-based tread depth measuring configurations and orientations disclosed herein with respect to any particular figure may likewise be applied in an alternative arrangement to any other figure. That is, the tread depth measuring configurations and orientations illustrated in each particular figure are not intended to be limiting, and it is contemplated that any configuration and orientation illustrated or disclosed could be interchanged with another configuration and orientation. 
     To the extent that the term “includes” or “including” is used in the specification or the claims, it is intended to be inclusive in a manner similar to the term “comprising” as that term is interpreted when employed as a transitional word in a claim. Furthermore, to the extent that the term “or” is employed (e.g., A or B) it is intended to mean “A or B or both.” When the applicants intend to indicate “only A or B but not both” then the term “only A or B but not both” will be employed. Thus, use of the term “or” herein is the inclusive, and not the exclusive use. See Bryan A. Gamer, A Dictionary of Modem Legal Usage  624  (2d. Ed. 1995). Also, to the extent that the terms “in” or “into” are used in the specification or the claims, it is intended to additionally mean “on” or “onto.” To the extent that the term “substantially” is used in the specification or the claims, it is intended to take into consideration the degree of precision available in the relevant industry. To the extent that the term “selectively” is used in the specification or the claims, it is intended to refer to a condition of a component wherein a user of the apparatus may activate or deactivate the feature or function of the component as is necessary or desired in use of the apparatus. To the extent that the term “operatively connected” is used in the specification or the claims, it is intended to mean that the identified components are connected in a way to perform a designated function. As used in the specification and the claims, the singular forms “a,” “an,” and “the” include the plural. Finally, where the term “about” is used in conjunction with a number, it is intended to include ±10% of the number. In other words, “about 10” may mean from 9 to 11. 
     As stated above, while the present application has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art, having the benefit of the present application. Therefore, the application, in its broader aspects, is not limited to the specific details, illustrative examples shown, or any apparatus referred to. Departures may be made from such details, examples, and apparatuses without departing from the spirit or scope of the general inventive concept.