Patent Publication Number: US-2016221404-A1

Title: Method and apparatus for measuring tire tread abrasion

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Korean Patent Application No. 10-2015-0014600, filed on Jan. 29, 2015, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
     BACKGROUND 
     1. Field 
     One or more exemplary embodiments relate to a method and an apparatus for measuring tire tread abrasion, and more particularly, to a method and an apparatus for measuring tire tread abrasion by analyzing a moving image captured by a camera. 
     2. Description of the Related Art 
     Deep grooves are provided to a tire tread so as to enhance a braking force and a driving force. Since a tire tread directly contacts a surface of a road, as a driving distance increases, treads  1500  and  1510 , shown in  FIG. 15 , are worn, and thus, a depth of a groove is reduced. Accordingly, a braking force deteriorates, and this affects safety. A driver may measure a depth of a tire tread, and if the depth of the tire tread is decreased, the driver needs to replace a tire. In a related art, a triangle mark is shown beside a tire tread in a related art, so as to easily indicate a time point when a tire is to be replaced. 
     However, a user may have to measure a depth of a tire and determine a point of time when the tire is to be replaced. Some drivers may not recognize a method of determining that a tire needs to be replaced due to a degree of abrasion of a tire tread. 
     SUMMARY 
     One or more exemplary embodiments include a method and an apparatus for easily measuring tire tread abrasion based on a moving image of a tire tread that a user captured by using a camera. 
     Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments. 
     According to one or more exemplary embodiments, a method of measuring tire tread abrasion includes: receiving a moving image of a tire; generating a three-dimensional (3D) image of the tire based on the moving image; and measuring tire tread abrasion based on a depth of a tread area in the 3D image. 
     According to one or more exemplary embodiments, a method of measuring tread abrasion of a tire, the measuring being performed by a terminal includes: capturing a moving image that includes a tire tread area; transmitting the moving image to a server; and receiving information about tread abrasion of the tire from the server. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings in which: 
         FIG. 1  illustrates a schematic configuration of a system for measuring tire tread abrasion according to an exemplary embodiment; 
         FIG. 2  is a block diagram of an abrasion measuring apparatus according to another exemplary embodiment; 
         FIG. 3  is a flowchart of an example of a method of measuring tire tread abrasion according to another exemplary embodiment; 
         FIG. 4  is a flowchart of an example of a method of generating a three-dimensional (3D) image by using a moving image so as to measure tire tread abrasion; 
         FIG. 5  illustrates a diagram of an example of converting two-dimensional (2D) coordinates of a plurality of still images into spatial coordinates in a 3D space; 
         FIG. 6  illustrates an example of a 3D image obtained from a moving image of a tire tread; 
         FIG. 7  is a flowchart of an example of a method of measuring tire tread abrasion based on a generated 3D image; 
         FIG. 8  illustrates an example of dividing a 3D image according to a size of a curvature of a pixel; 
         FIG. 9  illustrates an example of dividing a 3D image into a plurality of sections with reference to a direction and a width of a tread groove area; 
         FIG. 10  illustrates an example of a 3D image; 
         FIG. 11  illustrates an example of a method of determining a depth of a tread groove from the 3D image shown in  FIG. 10 ; 
         FIG. 12  illustrates an example of calibrating a 3D image into a near plane; 
         FIG. 13  is a block diagram of a terminal for measuring tire tread abrasion, according to an exemplary embodiment; 
         FIG. 14  is a flowchart of an example of a method of receiving information about tire tread abrasion, the receiving being performed by the terminal, according to an exemplary embodiment; and 
         FIG. 15  illustrates an example of tire tread abrasion in a related art. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, the present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the exemplary embodiments are merely described below, by referring to the figures, to explain aspects of the present description. 
     Hereinafter, a method and an apparatus for measuring tire tread abrasion will be described in detail by explaining exemplary embodiments with reference to the attached drawings. 
       FIG. 1  illustrates a schematic configuration of a system for measuring tire tread abrasion according to an exemplary embodiment. 
     Referring to  FIG. 1 , a user captures a moving image of a tire  100  by using a terminal  110 . The terminal  110  may be a camera, or a terminal that includes a camera module inside or outside the terminal  110 , such as a smartphone, a tablet personal computer (PC), or the like. 
     In the current embodiment, a moving image is defined as including a plurality of captured still images of an object, as well as a general a moving image. For example, two or more still images which are respectively captured at different locations and combined with each other, as well as a general moving image, are defined as a moving image. 
     The terminal  110  and an abrasion measuring apparatus  130  are connected to each other, via a wired or wireless communication network  120 . For example, if the terminal  110  is a smartphone, the terminal  110  may be connected to the tire recognition apparatus  130  via a mobile communication network such as long term evolution (LTE), 3 rd  generation (3G), or the like. As another example, if the terminal  110  includes a short-range communication module such as a universal serial bus (USB) port, an infrared communication module, or a Bluetooth module, the terminal  110  may be connected, via a USB port, to a third apparatus (not shown) that may be connected to an external network such as an Internet. A moving image captured by the terminal  110  may be transmitted to the tire recognition apparatus  130  via the third apparatus (not shown). 
     The tread measuring apparatus  130  measures abrasion of a tire tread by analyzing the moving image received from the terminal  110 , and then, provide information about whether to replace a tire or a point of time when the tire is to be replaced to the terminal  110 . 
     In the current embodiment, the abrasion measuring apparatus  130  and the terminal  110  are shown as separate elements. However, the abrasion measuring apparatus  130  may be implemented as software such as an application, stored in the terminal  110 , and thus, executed by the terminal  110 . 
       FIG. 2  is a block diagram of the abrasion measuring apparatus  130  according to another exemplary embodiment. 
     Referring to  FIG. 2 , the abrasion measuring apparatus  130  includes a reception unit  200 , a three-dimensional (3D) generation unit  210 , a tread area detection unit  220 , and an abrasion measuring unit  230 . 
     The reception unit  200  receives a moving image of a tire tread from the terminal  110 . As an example, the reception unit  200  may receive a moving image, captured by the terminal  110 , directly from the terminal  110  or via a third apparatus. As another example, if the abrasion measuring apparatus  130  is implemented to be included in the terminal  110 , the reception unit  200  may not be included in the tire recognition apparatus  130 . If a moving image does not consist of general consecutive images but consists of a plurality of still images that are non-consecutively captured, the reception unit  200  receives a plurality of still images. 
     The 3D image generation unit  210  generates the received moving image as a 3D image. A 3D image may be generated by using a binocular parallax that is generated from 2D images respectively captured in directions different from each other. Accordingly, the 3D image generation unit  210  divides the moving image into a plurality of still images, and then, generates a 3D image by using a binocular parallax between the plurality of still images. 
     In detail, the 3D image generation unit  210  divides a moving image of a tire tread into a plurality of still images, determine a corresponding relation between pixels of the plurality of still images, determine a photographing parameter regarding a photographing angle at which the moving image is captured and a photographing distance between the camera and the tire based on the determined corresponding relation between the pixels, and thus, generate a 3D image of a tread area. A method of generating a 3D image is described with reference to  FIGS. 4 and 5 . 
     As another example, if a moving image received by the reception unit  200  consists of a plurality of still images that are respectively captured, the 3D image generation unit  210  may not perform a process of dividing the moving image into still images. 
     The tread area detection unit  220  distinguishes a surface area from a tread groove area in a 3d image, and detects the tread groove area and the surface area. For example, since a curvature of an edge between a tread groove area and a surface area in a 3D image is great compared to that of other areas, the tread area detection unit  220  detects an edge area by analyzing a curvature of each pixel of a 3D image, and distinguishes the tread groove area from the surface area with reference to the detected edge area. 
     The abrasion measuring unit  230  measures tire tread abrasion by determining a depth between the tread groove area and the surface area which are detected by the tread area detection unit  220 . As an example, the abrasion detection unit  220  may correct the tread groove area and the surface area in the 3D image to obtain a near plane by using a plane approximation algorithm, and then, determine a depth of a tread groove based on the near plane. As another example, since tire tread abrasion may vary depending on a location of a tread groove, the abrasion measuring unit  230  divides the tread groove area into a plurality of sections, determines a depth of a groove according to each section, and then, measure tire tread abrasion with reference to a section having a deepest groove. 
     A size of a tire in the 3D image may different from a size of an actual tire. In this case, it may be difficult to accurately measure tire tread abrasion only by using a size of a depth of a tread groove obtained from the 3D image. 
     For this, the abrasion measuring unit  230  may measure tire tread abrasion by correcting a size of a depth of the tread groove, obtained from a 3D image, to a size of a depth of a tread groove in the actual tire or determining a depth of the tread groove in the 3D image by using a ratio between the depth of the tread groove and a width of a tread in the 3D image. 
     For example, if a size of a depth of the tread groove in a 3D image is to be corrected to a size of a depth of a tread groove in an actual tire, the abrasion measuring unit  230  corrects the depth of the tread groove in the 3D image in correspondence with a proportional size relationship between a width of a tread or a space between treads in the actual tire and a width of a tread or a space between treads in the 3D image. 
       FIG. 3  is a flowchart of an example of a method of measuring tire tread abrasion according to an exemplary embodiment. 
     Referring to  FIG. 3 , in operation S 300 , the abrasion measuring apparatus  130  obtains a moving image of a tire tread. In operation S 310 , the tire abrasion measuring apparatus  130  generates a 3D image of an area of the tire tread by using the moving image of the tire. Then, in operation S 320 , the abrasion measuring apparatus  130  measures tire tread abrasion by determining a depth of a tread groove from the 3D image. 
       FIG. 4  is a flowchart of an example of a method of generating a 3D image by using a moving image so as to measure tire tread abrasion.  FIG. 5  illustrates an example of converting two-dimensional (2D) coordinates of a plurality of still images into spatial coordinates in a 3D space. 
     Referring to  FIG. 4 , in operation S 400 , the abrasion measuring apparatus  130  divides a moving image into a plurality of still images. In operation S 410 , the abrasion measuring apparatus  130  determines a corresponding relation between pixels of a plurality of still images. For example, referring to  FIG. 5 , if pixels at a particular location of images of an object which are captured by the terminal  110  at different locations from each other, that is, a pixel P j,k−1  of a k-1th still image  500 , a pixel P j,k  of a kth still image  502 , and a pixel P j,k+1  of a k30 1th still image correspond to each other, the abrasion measuring apparatus  130  calculates and stores a corresponding relation between the respective pixels. This is generally referred to as stereo matching. In the current embodiment, various methods of determining a matching relation between pixels of still images by determining feature points  501  of the still images, in a related art, may be employed. 
     In operation S 420 , the abrasion measuring apparatus  130  calculates a relative relation between the plurality of still images and locations of the terminal  110  (that is, a camera used for the terminal  110 ) when each still image is captured, based on a corresponding relation between respective pixels of a plurality of still images. In other words, the abrasion measuring apparatus  130  reversely calculates a measuring parameter, for example, a focal length, a photographing angle, a location of a camera, or the like at which the plurality of still images are captured, based on a corresponding relation between pixels of a plurality of still images. 
     In operation S 430 , the abrasion measuring apparatus  130  determines points corresponding to spatial coordinates of each pixel in a 3D space by using a triangulation method based on a binocular parallax between the pixels of the plurality of still images, and a photographing direction in which the terminal  110  captures the moving image and a photographing location in which the terminal  110  captures the moving image with respect to the plurality of still images, and generates an image in a 3D space by combining the points corresponding to the spatial coordinates with each other. 
     For example, referring to  FIG. 5 , the abrasion measuring unit  130  may determine the respective pixels P j,k−1 , P j,k , and P j,k+1  corresponding to the feature points  501  in the k-1th still image  500 , the kth still image  502 , and the k+1th still image, determine a photographing location in which the terminal  110  captures the moving image and a photographing angle at which the terminal  110  captures the moving image with respect to each still image, and then, obtain spatial coordinates  520  by determining points in a space corresponding to the respective pixels by using a triangulation method. A 3D image is generated by connecting the points in the space which corresponds to the spatial coordinates  520  to each other. 
     If a moving image of a tire tread is captured, a location in which the terminal  110  captures the moving image may be moved. Thus, a plurality of still images in the moving image, obtained when the location in which the terminal  110  captures the moving image is moved, have binocular parallax.  FIG. 4  is a flowchart of an example of a method of generating a 3D image from a plurality of still images which are included in a moving image and have a binocular parallax. However, exemplary embodiments are not limited to the method described with reference to  FIG. 4 , and various methods of generating a 3D image in a related art may be employed. 
       FIG. 6  illustrates an example of a 3D image obtained from a moving image of a tire tread. 
     Referring to  FIG. 6 , the abrasion measuring apparatus  130  may divide a moving image into a plurality of still images, determine a relative location of a camera with respect to the plurality of still images and an angle at which the camera captures the plurality of still images, and thus, obtain the plurality of still images having a binocular parallax, like being photographed by a plurality of cameras  600 . 
     The abrasion measuring apparatus  130  generates a 3D image  610  of an area of a tire tread based on the plurality of still images having a binocular parallax. 
       FIG. 7  is a flowchart of an example of a method of measuring tire tread abrasion based on a generated 3D image. 
     Referring to  FIG. 7 , if the abrasion measuring apparatus  130  obtains a 3D image shown in  FIG. 6 , the abrasion measuring apparatus  130  analyzes a curvature of each pixel in the 3D image in operation S 700 . 
     In operation S 710 , the abrasion measuring apparatus  130  connects pixels, which have a size of a curvature similar to each other and whose distance from each other is within a certain range, to each other. An example of showing areas, distinguished from each other according to a size of a curvature of each pixel, in a color different from each other is shown in  FIG. 8 . A range of a size of a curvature for distinguishing areas from each other may be variously set according to exemplary embodiments. 
     For example, if pixels having a size of a curvature greater than a predetermined threshold value are connected to each other, an edge area  810  between a surface area and a groove area is detected in a 3D image. Additionally, if pixels having a value of a curvature approximating to 0 are connected to each other, the surface area and the groove area which are in the form of a plane are detected. 
     However, if areas are distinguished from each other by using a size of a curvature for each pixel in a 3D image, small noise areas may occur as shown in  FIG. 8 . Since sizes of such noise areas are very small compared to sizes of a surface area, a groove area, or an edge area, the noise areas may be removed by performing a process of removing areas having a smaller size that a predetermined size. In other words, as shown in  FIG. 8 , all areas that occur on the surface area and have a smaller size that a certain size may be absorbed into large areas to obtain a smooth plane. 
     In operation S 720 , the abrasion measuring apparatus  130  distinguishes a groove area  820  from a surface area  800  with reference to an area having a greatest curvature, that is, an edge area  810 . 
     The abrasion measuring apparatus  130  may directly obtain tire tread abrasion based on a depth of the tread groove area  820 . However, in operation S 730 , the abrasion apparatus  130  divides the tread groove area into a plurality of sections by taking into account that the tire tread abrasion may vary depending on a location in the tread groove area  820  at which the tire tread abrasion is measured. 
     Various methods of dividing a tread groove area into a plurality of sections may be present. As an example, referring to  FIG. 9 , the tread groove area  820  may be divided into a plurality of sections with reference to a direction and a width of the tread groove area  820 . In detail, the abrasion measuring apparatus  130  determines center axes  900  through  920  with respect to a direction of the tread groove area  820 , and determines a width of each tread groove based on direction vectors  930  through  950  perpendicular to the center axes  900  through  920 . Additionally, the abrasion measuring apparatus  130  may divide the tread groove area  820  into a plurality of sections  960 ,  962 ,  964 ,  966 ,  968 ,  970 , and  972  with reference to the direction and the width of the tread groove area  820 . 
     For example, with respect to a width of a tread groove in a direction perpendicular to the center axis  900  which is shown on a left side in  FIG. 9  since a center area of the tread groove is larger than other areas, the tread groove may be divided into three parts  960 ,  962 , and  964  with reference to the width thereof. Other areas may also be divided into small parts with reference to a width, or the like. Other various methods of dividing the tread groove area  820  into small parts in the units of a certain size of area or a certain length may be also used. 
     The abrasion measuring apparatus  130  may correct the tread groove area  820  and the surface area  800  to obtain a near plane. For example, referring to  FIG. 12 , the abrasion measuring apparatus  130  may correct surfaces of a tread groove area and a surface area to obtain a near plane  1200  by using a plane approximation algorithm such as a least squares fitting method. 
     In operation S 750 , the abrasion measuring apparatus  130  determines a depth of the tread groove area  820  based on the surface area  800 . For example, if a surface area and a tread groove area of a 3D image are distinguished from each other as shown in  FIG. 10 , a depth of a groove may be determined from a surface as shown in  FIG. 11 . Alternately, a depth of a groove may be determined by determining a depth of the edge area  810  that distinguishes the surface area  800  from the tread groove area  820 . If the near plane  1200  is obtained as shown in  FIG. 12 , a depth of a groove area may be determined based on the near plane  1200 . Additionally, if tread groove area  820  is divided into the plurality of sections  960 ,  962 ,  964 ,  966 ,  968 ,  970 , and  972 , a depth of the tread groove area  820  may be determined for each section, and then, a depth of a deepest location of the groove area may be determined as a depth of a groove of a tire tread. 
     The abrasion measuring apparatus  130  determines a degree of tire tread abrasion based on a depth of the tread groove area. Then, in operation S 760 , the abrasion measuring apparatus  130  may calculate and provide information about whether to replace a tire or a point of time when a tire is to be replaced to the terminal  110 . Since a size of a tire in a 3D image and a size of an actual tire are in a certain proportional relation, the abrasion measuring apparatus  130  may measure tire tread abrasion by using a depth of a groove obtained by correcting a tire in a 3D image to an actual tire, instead of using a depth of a groove in the 3D image. 
       FIG. 13  is a block diagram of the terminal  110  for measuring tire tread abrasion, according to an exemplary embodiment. 
     Referring to  FIG. 13 , the terminal  110  includes a moving image capturing unit  1300 , a transmission unit  1310 , and an abrasion output unit  1320 . 
     The moving image capturing unit  1300  captures a moving image of a tire. Like a camcorder, the moving image capturing unit  1300  may capture a moving image consisting of consecutive images or capture a plurality of still images. 
     The transmission unit  130  transmits the captured moving image to the abrasion measuring apparatus  130 . 
     The abrasion output unit  1320  receives various information about abrasion such as a degree of abrasion, whether to replace a tire, or a point of time when a tire is to be replaced from the abrasion measuring apparatus  130 , and outputs the information. 
       FIG. 14  is a flowchart of an example of a method of receiving information about tire tread abrasion, the receiving being performed by the terminal  110 , according to an exemplary embodiment. 
     Referring to  FIG. 14 , the terminal  110  captures a moving image of a tire in operation S 1400 , and then, transmits the moving image to the abrasion measuring apparatus  130  in operation S 1410 . In operation S 1420 , the terminal  1100  receives information about tire tread abrasion from the abrasion measuring apparatus  130 , and outputs the information. 
     According to one or more exemplary embodiments, the method and the apparatus for measuring tire tread abrasion may allow a user to easily determine tire tread abrasion by capturing a moving image of a tire by using a camera included in a smartphone or the like, without having to measure a depth of a tread groove of a tire. Additionally, the method and the apparatus may indicate a point of time when the tire needs to be replaced. Additionally, if it is time to replace a tire, the method and the apparatus may also indicate a point of time when the tire needs to be replaced and information about the tire together. 
     Exemplary embodiments can also be embodied as computer-readable codes on a computer-readable recording medium. The computer-readable recording medium is any data storage device that can store data which can be thereafter read by a computer system. Examples of the computer-readable recording medium include read-only memory (ROM), random-access memory (RAM), CD-ROMs, magnetic tapes, floppy disks, and optical data storage devices. The computer-readable recording medium can also be distributed over network coupled computer systems so that the computer-readable code is stored and executed in a distributed fashion. 
     It should be understood that exemplary embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each exemplary embodiment should typically be considered as available for other similar features or aspects in other exemplary embodiments. 
     While one or more exemplary embodiments have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the inventive concept as defined by the following claims.