System and method for field calibration of image capture modules

Abstract

Systems and methods for field calibration of an image capture module are disclosed. The system comprises: a vehicle having a light beam for orienting components of the system for field calibration while the vehicle is traveling; and an image capture module operatively coupled to the light beam, comprising: a camera configured to capture an image of a target disposed near the railway track; and a memory configured to store the captured image of the target; an image capture module is configured to perform field calibration of the image capture module by: capturing a first image of a target via the camera; initializing a vehicle encoder operatively coupled to the vehicle with a vehicle encoder rate; adjusting a contrast between two pixels identifying a boundary of a bright portion and a dark portion of the target; comparing the number of lateral pixels with the number of longitudinal pixels; the vehicle encoder rate is adjusted until the number of lateral pixels matches the number of longitudinal pixels.

Description

[0001] This application is a divisional application of the invention patent application with the application date of February 25, 2021, application number 202180021253.5, and name “System and method for calibrating image capture module”. Technical Field

[0002] The present disclosure relates generally to image capture modules and, more particularly, to a system and method for calibrating an image capture module. Background Art

[0003] Some vehicles use cameras to capture images of objects in the vehicle's surroundings. These images can be used to identify and / or locate objects in the surrounding environment. However, images captured from a vehicle while it is moving can be blurry or distorted, which can lead to inaccurate object identification and / or location. Summary of the Invention

[0004] Aspects of the invention are set out in the independent claims and preferred features are set out in the dependent claims. Features of one aspect may apply to any aspect alone or in combination with other aspects.

[0005] According to one embodiment, a method includes the steps of capturing a first image of a target by a camera of an image capture module. The image capture module and the drum are attached to a fixture, and the target is attached to the drum. The method also includes the steps of determining the number of lateral pixels in a lateral pitch distance of the target image, determining a lateral object pixel size based on the number of lateral pixels, and determining a drum encoder rate based on the lateral object pixel size. The drum encoder rate is programmed into a drum encoder connected to the drum. The method also includes the steps of capturing a second image of the target by the camera of the image capture module while the target rotates about the axis of the drum, determining the number of longitudinal pixels in a longitudinal pitch distance of the second image, and comparing the number of lateral pixels to the number of longitudinal pixels.

[0006] In some embodiments, the drum encoder rate is the number of electrical pulses generated by the drum encoder during one rotation of the drum encoder shaft. In some embodiments, the drum encoder rate is calculated using the drum circumference and the horizontal object pixel size. The target can be a checkerboard pattern consisting of a plurality of black and white squares, where the horizontal spacing can represent the width of one of the squares and the vertical spacing can represent the length of one of the squares.

[0007] In some embodiments, the method includes the steps of: determining whether the number of horizontal pixels matches the number of vertical pixels in response to comparing the number of horizontal pixels to the number of vertical pixels; and calculating a vehicle encoder rate based on the drum encoder rate. In some embodiments, the method further includes the steps of programming the vehicle encoder rate into a vehicle encoder attached to a wheel of the vehicle; and capturing an image of a second object via a camera of an image capture module, wherein the image capture module is attached to the vehicle and the second object is attached to the road.

[0008] In some embodiments, the method includes the steps of: determining, in response to comparing the number of horizontal pixels to the number of vertical pixels, that the number of horizontal pixels is different from the number of vertical pixels, adjusting the drum encoder rate to the adjusted drum encoder rate, and programming the adjusted drum encoder rate into the drum encoder. The method also includes the steps of capturing a third image of the target with a camera of the image capture module while the target rotates about the axis of the drum, determining the number of vertical pixels in a vertical pitch distance of the third image, and comparing the number of horizontal pixels to the number of vertical pixels in the vertical pitch distance of the third image. In some embodiments, the method includes focusing the camera of the image capture module on the target under constant lighting conditions and obtaining a maximum contrast between two pixels identifying a boundary between a bright portion and a dark portion of the target.

[0009] According to another embodiment, a system includes a fixture, a roller attached to the fixture, a target attached to the roller, a roller encoder attached to the roller, and an image capture module attached to the fixture. The image capture module includes a camera that captures a first image of the target and captures a second image of the target as the target rotates about the axis of the roller. The system also includes one or more controllers communicatively coupled to the roller encoder and the camera. The one or more controllers determine the number of horizontal pixels in the horizontal pitch distance of the image of the target, determine the horizontal object pixel size based on the number of horizontal pixels, and determine the roller encoder rate based on the horizontal object pixel size, wherein the roller encoder rate is programmed into the roller encoder attached to the roller. The one or more controllers further determine the number of longitudinal pixels in the longitudinal pitch distance of the second image and compare the number of horizontal pixels to the number of longitudinal pixels.

[0010] According to yet another embodiment, one or more computer-readable storage media contain instructions that, when executed by a processor, cause the processor to perform operations including the steps of capturing a first image of a target by a camera of an image capture module. The image capture module and a drum are attached to a fixture, and the target is attached to the drum. The operations further include determining a number of horizontal pixels in a horizontal pitch distance of the target image, determining a horizontal object pixel size based on the number of horizontal pixels, and determining a drum encoder rate based on the horizontal object pixel size, wherein the drum encoder rate is programmed into a drum encoder attached to the drum. The operations further include capturing a second image of the target by the camera of the image capture module while the target rotates about an axis of the drum, determining a number of vertical pixels in a vertical pitch distance of the second image, and comparing the number of horizontal pixels to the number of vertical pixels.

[0011] Technical advantages of certain embodiments of the present disclosure may include one or more of the following. The present disclosure describes systems and methods for bench calibration of image capture modules that can reduce the time and / or personnel required to calibrate image capture modules on site. Certain embodiments of the present disclosure use a rotating drum located in a laboratory to simulate a moving road, which allows an operator (e.g., a computer programmer) to test the calibration system at full speed with real-time images. Since the time spent by personnel to calibrate image capture modules on site under dangerous conditions (e.g., working on roads and under heavy equipment) is reduced, the number of on-site personnel is reduced, and the cost of expensive field testing can be minimized, the systems and methods described herein for bench calibration of image capture modules can improve the safety and efficiency of field calibration. The systems and methods described in the present disclosure can be extended to different transportation infrastructures, including rail, road, and waterways.

[0012] Other technical advantages will be apparent to those skilled in the art from the following drawings, descriptions, and claims.In addition, although specific advantages are listed above, various embodiments may include all, some, or none of the listed advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] To assist in understanding the present disclosure, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

[0014] Figure 1 An example system for in-situ calibration of an image capture module and a vehicle encoder is shown;

[0015] Figure 2 Show that it can be Figure 1 An example image capture module used in the system;

[0016] Figure 3An example system for bench calibrating an image capture module is shown;

[0017] Figure 4 An example method for in-situ calibration of an image capture module is shown;

[0018] Figure 5 An example method for stage calibration of an image capture module is shown; and

[0019] Figure 6 An example computer system is shown that may be used by the systems and methods described herein. DETAILED DESCRIPTION

[0020] Some vehicles include image capture systems that capture images while the vehicle is in motion. Machine vision models can use these images to detect and / or locate objects in the vehicle's surroundings. Embodiments of the present disclosure describe systems and methods for calibrating the image capture modules and / or rotary encoders used in these systems. These calibration procedures ensure that the image capture modules and rotary encoders used in these systems are synchronized and provide clear, high-contrast, and properly scaled images.

[0021] Figures 1 to 6 Example systems and methods for calibrating an image capture module are shown. Figure 1 shows an example system for in-situ calibration of an image capture module, Figure 2 Show that it can be Figure 1 An example image capture module used by the system. Figure 3 An example system for bench calibrating an image capture module is shown. Figure 4 shows an example method for calibrating an image capture module in the field, Figure 5 An example method for stage calibration of an image capture module is shown. Figure 6 An example computer system is shown that may be used by the systems and methods described herein.

[0022] Figure 1 An example system 100 is shown for calibrating an image capture module 140 in the field. The system 100 or portions thereof may be associated with an entity, which may include any entity, such as a business, a company (e.g., a railroad, a transportation company, etc.), or a government agency (e.g., a department of transportation, a department of public safety, etc.) that calibrates the image capture module 140 in the field. The elements of the system 100 may be implemented using any suitable combination of hardware, firmware, and software. For example, the elements of the system 100 may be implemented using Figure 6 It is implemented by one or more components of a computer system.

[0023] System 100 includes a vehicle 110, a vehicle encoder 120, a beam 130, one or more image capture modules 140, a computer 150, a network 160, and a target 170. Vehicle 110 of system 100 is any machine capable of autonomous movement. Vehicle 110 can be a car, a locomotive, a truck, a bus, an airplane, or any other machine suitable for movement. Vehicle 110 can operate at any speed that allows one or more components of beam 130 (e.g., sensors, cameras, etc.) to capture images. For example, vehicle 110 can be a rail vehicle traveling at 65 miles per hour (mph). Road 112 of system 100 is any path that accommodates vehicle 110. For example, vehicle 110 can travel along road 112. Road 112 can include roads, highways, railroad tracks, waterways, etc.

[0024] The vehicle encoder 120 of the system 100 is a rotary encoder or other timing device for measuring axle rotations. The vehicle encoder 120 can measure the number of axle rotations. The vehicle encoder 120 can be attached to an axle of the vehicle 110. The vehicle encoder 120 can be physically and / or logically connected to one or more components of the system 100. For example, the vehicle encoder 120 can be physically and / or logically connected to one or more cameras and / or sensors of the image capture module 140. As another example, the vehicle encoder 120 can be physically and / or logically connected to the computer 150.

[0025] The vehicle encoder 120 can communicate with the cameras of the image capture module 140 via a controller to ensure that the cameras capture images with the same perspective and scale, regardless of the speed at which the vehicle 110 is traveling. For example, the vehicle encoder 120 can synchronize with multiple cameras of the image capture module 140 to ensure that all cameras capture images simultaneously. As another example, the vehicle encoder 120 can synchronize with the cameras of the image capture module 140 to ensure that a camera traveling with the vehicle 110 at a first speed (e.g., 10 miles per hour) captures images with the same perspective and scale as a camera traveling with the vehicle 110 at a second speed (e.g., 65 miles per hour).

[0026] The beam 130 of the system 100 is a structure that includes and directs components for capturing images (e.g., image capture module 140). In certain embodiments, the beam 130 operates similarly to a flatbed document scanner, except that the beam 130 is in motion when capturing images of stationary physical objects. The beam 130 engages the vehicle 110. For example, the beam 130 can be bolted to a subframe attached to the vehicle 110. Figure 1In the illustrated embodiment, the beam 130 has three sections, including two end sections and a center section. The beam 130 has a gull-wing configuration such that the center section bends inwardly toward the center of the beam 130. The gull-wing configuration allows the image capture components (e.g., sensors, cameras, etc.) of the image capture module 140 within the beam 130 to be properly oriented therein relative to the physical object being captured. In some embodiments, the center section of the beam 130 is omitted, and each end section is connected to the vehicle 110. The beam 130 can be made of metal (e.g., steel or aluminum), plastic, or any other material suitable for accommodating the components of the beam 130 and for attaching the beam 130 to the vehicle 110.

[0027] The light beam 130 may include one or more openings. The openings may be used to place the image capture module 140 within the light beam 130. The openings may allow for installation, adjustment, and maintenance of the image capture module 130. Although the light beam 130 is Figure 1 Although shown as having a particular size and shape, the beam 130 may have any size and shape suitable for accommodating and orienting the image capture module 140. Other factors that may contribute to the design of the beam 130 include shock resistance, vibration resistance, weatherproofing considerations, durability, ease of maintenance, calibration considerations, and ease of installation.

[0028] The image capture modules 140 of the system 100 are used to capture images while the vehicle 110 is traveling. Each image capture module 140 may include one or more sensors, one or more cameras, etc. One or more image capture modules 140 may be attached to the vehicle 110 at any location that allows the image capture module 140 to capture images of the environment surrounding the vehicle 110. Figure 1 In the illustrated embodiment, image capture module 140 is positioned within light beam 130 .

[0029] In some embodiments, each end portion of the beam 130 houses one or more image capture modules 140. For example, the first end portion of the beam 130 can house an image capture module 140 that includes two downward-facing cameras for capturing images of the connection area and the ballast area of ​​the track. The first end portion of the beam 130 can house the two downward-facing cameras in a portion of the first end portion that is substantially horizontal with the track. The second end portion of the beam 130, opposite the first end portion, can house two image capture modules 140, each including two angled cameras that capture images of both sides of the track and the track fastening system. The second end portion of the beam 130 can house four angled cameras in a portion of the second end portion that is angled (e.g., at a 45-degree angle) with respect to the track.

[0030] Depending on the sensing and / or measurement requirements, the image capture module 140 may include various types of sensors. The sensors housed by the image capture module 140 may include optical sensors (e.g., cameras for visible light (monochrome and color), infrared, ultraviolet, and / or thermal), motion sensors (e.g., gyroscopes and accelerometers), light detection and ranging (LIDAR) sensors, hyperspectral sensors, global positioning system (GPS) sensors, etc. Optical sensors and lasers may be used together for laser triangulation to measure deflection or profile. LiDAR sensors may be used to generate three-dimensional (3D) point cloud data. Hyperspectral sensors may be used for specific wavelength responses. Figure 2 An example image capture module 140 is described in .

[0031] Computer 150 of system 100 represents any suitable computing component that can be used to process information for system 100. Computer 150 can coordinate one or more components of system 100. Computer 150 can receive data from image capture module 140 and / or vehicle encoder 120. Computer 150 can monitor the input and / or output of image capture module 140 and / or vehicle encoder 120. Computer 150 can include communication functionality that allows a user (e.g., a technician) to directly engage with system 100. For example, a user can access computer 150 through an interface of computer 150 (e.g., a screen, graphical user interface (GUI), or panel). Computer 150 can be a laptop, desktop computer, smartphone, tablet, personal digital assistant, wearable computer, etc. Computer 150 can be located inside or outside of vehicle 110. Computer 150 can communicate with one or more components of system 100 via network 160.

[0032] The network 160 of the system 100 is any type of network that facilitates communication between the components of the system 100. One or more portions of the network 160 may include an ad hoc network, an intranet, an extranet, a virtual private network (VPN), a local area network (LAN), a wireless local area network (WLAN), a wide area network (WAN), a wireless wide area network (WWAN), a metropolitan area network (MAN), a portion of the Internet, a portion of the public switched telephone network (PSTN), a cellular telephone network, a 3G network, a 4G network, a 5G network, a long-term evolution (LTE) cellular network, a combination of two or more of these networks, or other suitable types of networks. One or more portions of the network 160 may include one or more access (e.g., mobile access), core, and / or edge networks. The network 160 may be any communication network, such as a private network, a public network, a connection via the Internet, a mobile network, a Wi-Fi network, a Bluetooth network, etc. One or more components of the system 100 may communicate via the network 160. For example, the computer 150 may communicate via the network 160, including receiving information from the image capture module 140 and / or the vehicle encoder 120.

[0033] Target 170 of system 100 is an object used to calibrate image capture module 140 and / or vehicle encoder 120. In certain embodiments, target 170 is placed in clear view of image capture module 140. For example, target 170 can be fixed to road 112 (e.g., railroad tracks) in clear view of the camera of image capture module 140. Target 170 includes a calibration pattern. The calibration pattern can be of any suitable size, shape, and / or design. Calibration pattern designs can include a checkerboard pattern, a chessboard pattern, a circular grid pattern, a ChArUco board pattern, and the like. For example, the calibration pattern can be a printed black and white checkerboard pattern comprising a plurality of black and white squares. The calibration pattern can have a spacing between 0.375 inches and 2.0 inches (e.g., 0.5 inches, 1.0 inches, etc.). The spacing represents the length / width of one square in the checkerboard pattern. In certain embodiments, the calibration pattern can include cells having unequal aspect ratios. For example, the length of each cell can be twice the width of each cell.

[0034] In operation, the vehicle encoder rate is programmed into the vehicle encoder 120. The vehicle encoder rate is the number of electrical pulses generated by the vehicle encoder 120 in one rotation of the shaft of the vehicle encoder 120. Figure 3 and Figure 5As described in

[15] , the vehicle encoder rate can be determined based on calibration data previously generated during a bench calibration procedure. If bench calibration data is not available, an arbitrary initial value for the vehicle encoder rate can be programmed into the vehicle encoder 120. In some embodiments, the vehicle encoder rate programmed into the vehicle encoder 120 is an integer. In some embodiments, an operator programs the vehicle encoder rate into the vehicle encoder 120.

[0035] The vehicle encoder 120 and image capture module 140 of system 100 are fixed to vehicle 110. Considering the camera of the image capture module to be calibrated, a target 170 of system 100 is fixed to road 112. Target 170 is positioned perpendicular to the axis of the camera of image capture module 140. The camera of image capture module 140 is activated, and an operator observes the current focus of the camera under constant lighting conditions. If the contrast between two pixels identifying the boundary between the bright and dark portions of target 170 is less than the maximum contrast achievable (or less than the contrast observed during the gantry calibration process), the operator unlocks the camera's focus mechanism and adjusts the focus until the maximum contrast is achieved. The focus mechanism is then locked.

[0036] Image capture module 140 is connected to computer 150 via network 160. Computer 150 includes image capture software. Image capture module 140 captures a first image of target 170, which is displayed on computer 150. An operator determines the number of lateral (e.g., cross-web) pixels in the lateral pitch distance of the first image of target 170 and determines the lateral object pixel size (OPS) by dividing the pitch of target 170 by the number of lateral pixels in the pitch area. A test vehicle encoder rate is then determined by dividing the wheel circumference of vehicle 110 by the lateral OPS. If the test vehicle encoder rate differs from the initial vehicle encoder rate programmed into vehicle encoder 120, the test vehicle encoder rate is programmed into vehicle encoder 120. The image capture software of computer 150 is triggered by vehicle encoder 120, and vehicle 110 moves forward or backward over target 170.

[0037] As vehicle 110 moves over target 170, image capture device 140 captures a second image of target 170. An operator of computer 150 determines (e.g., counts) the number of light or dark longitudinal (e.g., down-web) pixels in one longitudinal interval of each second image and compares the number of down-web pixels to the number of down-web pixels. If the number of down-web pixels matches the number of down-web pixels, image capture module 140 and vehicle encoder 120 are calibrated. If the number of down-web pixels differs from the number of down-web pixels, the vehicle encoder rate is adjusted until the number of down-web pixels matches the number of down-web pixels. Thus, system 100 can be used to calibrate image capture module 140 and vehicle encoder 120 to ensure that system 100 captures sufficient images that can be used to accurately identify objects in the environment surrounding vehicle 110.

[0038] although Figure 1 A particular arrangement of vehicle 110, vehicle encoder 120, beam 130, image capture module 140, computer 150, network 160, and target 170 is shown, but the present disclosure contemplates any suitable arrangement of vehicle 110, vehicle encoder 120, beam 130, image capture module 140, computer 150, network 160, and target 170. For example, computer 150 may be located inside vehicle 110. Vehicle 110, vehicle encoder 120, beam 130, image capture module 140, and computer 150 may be physically or logically co-located, in whole or in part, with one another.

[0039] although Figure 1 A particular number of vehicles 110, vehicle encoders 120, beams 130, image capture modules 140, computers 150, networks 160, and targets 170 are shown, but the present disclosure contemplates any suitable number of vehicles 110, vehicle encoders 120, beams 130, image capture modules 140, computers 150, networks 160, and targets 170. For example, system 100 may include a first beam 130 located at a front end of vehicle 110 and a second beam 130 located at a rear end of vehicle 110. As another example, system 100 may include multiple computers 150. One or more components of system 100 may be configured using Figure 6 It is implemented by one or more components of a computer system.

[0040] Figure 2 Shows that the Figure 1 The system 100 may be used with an example image capture module 140. The image capture module 140 includes a camera 210, a lens 220, a top plate 230, a base plate 240, a cover plate 250, a bolt 260, and an opening 270. The camera 210 is any device that captures an image. For example, the camera 210 may capture Figure 1As another example, camera 210 can capture images of track components (e.g., track joints, switches, frogs, fasteners, ballast, rail heads, and / or sleepers). In some embodiments, camera 210 includes one or more sensors.

[0041] One or more cameras 210 can capture images from different angles. For example, one or more cameras 210 can capture images of two tracks of a railway system at any given location. Each beam (e.g., Figure 1 The beam 130 may include a plurality of cameras 210. The beam may include aiming directly downward to capture a target (e.g., Figure 1 The light beam may include a first camera 210 that captures an overhead image of a target 170 in the image, a physical object, etc. The light beam may include a second camera 210 that is aimed downward and outward to capture an angled image of the target, physical object, etc.

[0042] Camera 210 may be a line scan camera. A line scan camera includes a single row of pixels. Camera 210 may be a dual line scan camera. A dual line scan camera includes two rows of pixels that can be captured and / or processed simultaneously. As camera 210 moves over a physical object, camera 210 may capture images so that a complete image of the physical object can be reconstructed line by line in software. Camera 210 may have a capture rate of up to 140 kHz. Camera 210 may have a resolution and optics for detecting physical objects of at least 1 / 16 inch in size. In some embodiments, camera 210 includes a lens 220 that focuses incident light and directs it to a sensor of camera 210. Lens 220 may be a piece of glass or other transparent material. Lens 220 may be made of any suitable material (e.g., steel, aluminum, glass, plastic, or a combination thereof).

[0043] The top plate 230 and base plate 240 are structural elements used to position, support, and / or stabilize one or more components of the image capture module 140 (e.g., the camera 210 or the sensor). The top plate 230 and base plate 240 can be made of any suitable material (e.g., steel, aluminum, plastic, glass, etc.). The top plate 230 can be connected to the base plate 240 via one or more bolts 260. The bolts 260 (e.g., locating bolts) can be used to change the pitch and / or roll direction of the camera 210. For example, the bolts 260 can be used to change the effective height between the top plate 230 and base plate 240. The top plate 230 and / or base plate 240 can be adjusted to reduce vibration and / or shock to the image capture module 140. The top plate 230 or base plate 240 can include a resistive heating element to provide a warm operating environment for the camera 210 and lens 220 during cold weather.

[0044] The cover plate 250 is a plate that covers the substrate 240. The cover plate 250 can be made of any suitable material (e.g., glass, steel, aluminum, etc.). The cover plate 250 includes an opening 270. The opening 270 can serve as an aperture for the lens of the camera 210 to observe the physical object. The opening 270 allows sensing signals from the surrounding environment to be transmitted to the sensor of the camera 210. The opening 270 can be of any suitable size (e.g., oval, rectangular, etc.) to accommodate the view of the camera 210. The lens 220 of the camera 210 can be directly located above the opening 270.

[0045] although Figure 2 A particular arrangement of camera 210, lens 220, top plate 230, base plate 240, cover plate 250, bolts 260, and opening 270 is shown, but this disclosure contemplates any suitable arrangement of camera 210, lens 220, top plate 230, base plate 240, cover plate 250, bolts 260, and opening 270. Figure 2 A specific number of cameras 210, lenses 220, top plates 230, base plates 240, cover plates 250, bolts 260, and openings 270 are shown, but the present disclosure contemplates any suitable number of cameras 210, lenses 220, top plates 230, base plates 240, cover plates 240, bolts 260, and openings 270. For example, image capture module 140 may include multiple cameras 210. As another example, in some embodiments, image capture module 140 may not include multiple cameras 210. Figure 2 Certain components (e.g., substrate 240) are shown. One or more components of image capture module 140 may be used Figure 6 It can be implemented by one or more components of a computer system.

[0046] Figure 3 An example system 300 is shown for performing gantry calibration of the image capture module 140. Gantry calibration includes a calibration process in which the image capture module is calibrated on a gantry using a calibration device to simulate a process, rather than calibrating the image capture module 140 in situ using the actual process itself. The system 300 simulates a road (e.g., Figure 1 The system 300 or a portion thereof may be associated with an entity, which may include any entity, such as a business, a company (e.g., a railroad company, a transportation company, etc.), or a government agency (e.g., a department of transportation, a department of public safety, etc.) that performs gantry calibration of the image capture module 140. The elements of the system 300 may be implemented using any suitable combination of hardware, firmware, and software. For example, the elements of the system 300 may be implemented using Figure 6 It is implemented by one or more components of a computer system.

[0047] Figure 3The system 300 includes an image capture module 140, a computer 150, a network 160, a fixture 310, a roller 320, a motor 330, a motor controller 340, and a roller encoder 350. The fixture 310 of the system 300 is any structure for supporting one or more components of the system 300. The fixture 310 may include one or more frames, panels, brackets, fasteners (e.g., screws, bolts, etc.), etc. One or more components of the system 300 may be mounted on the fixture 300. Figure 3 In the illustrated embodiment, the image capture module 140 , the drum 320 , the motor 330 , the motor controller 340 , and the drum encoder 350 are mounted on a fixture 310 .

[0048] The image capture module 140 is mounted on the fixture 310 with a fixed working distance between the image capture module 140 and the target 322. This working distance is a nominal working distance and may be used in different vehicles (e.g., Figure 1 In some embodiments, Figure 3 The fixed working distance between the image capture module 140 and the target 322 is substantially (e.g., within 5%) equal to that installed on the Figure 1 The image capture assembly 140 on the vehicle 110 and fixed to Figure 1 The image capture module 140 may be physically and / or logically connected to one or more components of the system 300. For example, the image capture module 140 may be physically and / or logically connected to the drum encoder 350. As another example, the image capture module 140 may be physically (e.g., via a wired connection) and / or logically (e.g., through the network 160) connected to the computer 150.

[0049] The roller 320 of the system 300 is an object that rotates about an axis 360. The roller 320 is used to simulate a road moving below the image capture module 140 (e.g., Figure 1 The roller 320 may be of any suitable shape or size that allows for rotation about the axis 360. Figure 3 In the embodiment shown, drum 320 is cylindrical. In certain embodiments, axis 360 passes through the center of drum 320. Drum 320 can rotate around an axis positioned along axis 360. For example, a cylindrical axis can be placed along the length (or a portion thereof) of the core of drum 320, and drum 320 can rotate between the axes. Drum 320 can be any suitable material (e.g., plastic, metal, wood, fabric, a combination thereof, etc.). For example, drum 320 can be a hollow plastic cylinder with a metal cap at each end. The axis of drum 320 can pass through the center of each metal cap.

[0050] Target 322 of system 100 is an object used to calibrate camera 120 and / or drum encoder 320. Target 3222 of system 300 is attached to drum 320. Target 322 is coaxial with and synchronously positioned with drum encoder 350. Target 3222 can be any suitable material (e.g., paper, fabric, plastic, ink, combinations thereof, etc.). In certain embodiments, target 322 can be fastened to drum 320 using one or more fasteners (e.g., adhesive, screws, pins, nails, etc.). For example, target 322 can be bonded to the outer or inner surface of drum 320. In certain embodiments, drum 322 is a hollow transparent tube, and target 322 is placed on the inner surface of the hollow transparent tube so that target 322 is visible from the outside of drum 322. In some embodiments, target 322 is part of drum 320. For example, target 322 can be printed directly on drum 320.

[0051] Target 322 includes a calibration pattern 324. Calibration pattern 322 can be any suitable size, shape, and / or design. The design of calibration pattern 324 can include a checkerboard pattern, a chessboard pattern, a circular grid pattern, a ChArUcoboard pattern, and the like. For example, calibration pattern 324 can be a printed black and white checkerboard pattern with a spacing between 0.375 inches and 2.0 inches (e.g., 0.5 inches, 1 inch, etc.). The spacing represents the length / width of one square of the checkerboard pattern. In some embodiments, calibration pattern 324 can include cells with unequal aspect ratios. For example, the length of each cell can be twice the width of each cell. The calibration pattern 324 of target 322 is Figure 1 The calibration pattern of target 170 is the same as that of target 170. In some embodiments, Figure 1 Target 322 and target 170 are the same target.

[0052] The motor 330 of the system 300 is any machine that starts the drum 320 rotating. The motor 330 can be an alternating current (AC) motor, a direct current (DC) motor, a single phase motor (e.g., 115 / 230 volts), a three phase motor (e.g., 230 / 460 volts), etc. The motor can have a revolution per minute (RPM) of 1000 to 8000 (e.g., 1700-1800). The motor 330 can be physically or logically connected to the drum 320. For example, a belt 370 can be used to connect the motor 330 to a rod that passes through the axis 360 of the drum 320. The belt 370 is used to transfer the driving force from the motor 330 to the drum 320. The motor 330 can be attached to the fixture 310 at any suitable location. Figure 3In the embodiment shown, the motor 330 is attached to the base of the fixture 310 .

[0053] The motor controller 340 of the system 300 controls the operation of the motor 330. For example, the motor controller 340 can be used to start the rotation of the motor 330, adjust the speed of the motor 330, etc. In some embodiments, the motor controller 340 is manually operated by one or more users. The motor controller 340 may include one or more buttons, switches, displays, touch sensors, GUIs, etc., which allow one or more users (e.g., operators, technicians, etc.) to input information. For example, the motor controller 340 may include an on / off switch that allows the user to turn the motor on and / or off, up / down buttons that allow the user to increase / decrease the speed of the motor, etc. In some embodiments, the motor controller 340 can be connected to the computer 150 via the network 160, which allows the motor controller 340 to be remotely operated. The motor 330 and the motor controller 340 drive the roller 320 at a user-selectable rate (e.g., 10 to 70 miles per hour). In some embodiments, the roller 320 and Figure 1 The vehicle 110 is driven in proportion to its maximum speed (eg, 65 or 70 mph).

[0054] The drum encoder 350 of the system 300 is a rotary encoder or other timing device used to measure the rotation of the axle. Figure 1 The drum encoder 350 can be the same as the vehicle encoder 120 used in the system 100 (e.g., the same make and model). The drum encoder 350 can measure the number of times the shaft rotates. The drum encoder 350 can be physically and / or logically connected to one or more components of the system 300. For example, the drum encoder 350 can be physically attached to the drum 320. As another example, the drum encoder 350 can be physically and / or logically connected to the image capture module 140. As yet another example, the drum encoder 350 can be physically (e.g., via a wired connection) and / or logically (e.g., via the network 160) connected to the computer 150.

[0055] In operation, a user (eg, an operator) directs the image capture module 140 (or a portion thereof, such as Figure 2 The camera 210) is mounted on the fixture 310, and the image capture module 140 (such as Figure 2One or more components of the camera 210) are connected to a computer 150 (e.g., a computer). The computer 150 includes image capture software. A user turns on (e.g., switches) the power of the image capture module 140. The user unlocks the focus lock mechanism of the image capture module 140 and focuses the camera of the image capture module 140 on the target 322 under constant lighting conditions. Successful focus is achieved when maximum contrast is obtained between two pixels that identify the boundary of the bright and dark portions of a calibration pattern 324 (e.g., a checkerboard pattern) that identifies the target 322. The user then locks the focus mechanism of the image capture module 140. From the image displayed on the computer 150, the user observes a black or white area on the target 322 that is located in the middle of the field of view 380 of the camera of the image capture module 140. The field of view 380 may represent the angle at which the camera of the image capture module 140 picks up electromagnetic radiation. The field of view 380 may be limited by the area of ​​the image displayed on the computer 150. The operator of the computer 150 counts the number of bright pixels or dark pixels that are laterally spaced in the direction X of the target 322. Figure 3 In the illustrated embodiment, direction X is parallel to axis 360. The lateral object pixel size (OPS) is calculated by dividing the lateral pitch of target 322 by the number of pixels in the lateral pitch. For example, if the lateral pitch distance of target 322 is equal to one inch, and the number of pixels in the one-inch pitch distance of target 322 is 52, then OPS is equal to one inch divided by 52, which is equal to 0.01923 inches per pixel. OPS indicates the actual physical size represented by one pixel at a specified working distance (e.g., the distance between the camera of image capture module 140 and target 322).

[0056] The measurement and calibration OPS can ensure that objects depicted in images captured by the image capture module 140 are properly scaled and that data is not lost between pixels when the image capture module 140 is in field operation. In some embodiments, the pixels are square or approximately square (e.g., having equal length and width within a two percent tolerance). Due to limitations of the camera of the image capture module 140 and / or the drum encoder 350, some margin may be allowed.

[0057] The encoder rate of the drum encoder 350 is determined based on the OPS. The drum encoder rate is the number of electrical pulses generated by the drum encoder 350 during one rotation of the drum encoder 350 shaft. The drum encoder rate is equal to the circumference of the drum 320 divided by the transverse OPS. For example, if a drum with a diameter of 10.5 inches has a drum circumference of 32.9867 inches and a transverse OPS of 0.01923 inches, the drum encoder rate is 32.9867 inches / revolution divided by 0.01923 inches, which equals 1715.31 pulses (pixels) per revolution.

[0058] In some embodiments, the drum encoder rate is programmed into the drum encoder 350 as an integer value. For example, the drum encoder 350 can be programmed to 1715 or 1716 pulses per revolution. The user can set the motor controller 340 to rotate the drum 320 at a low speed. The low speed can be in the range of 5 to 20 mph (e.g., 10 mph). The image capture module 140 collects images while the drum 320 rotates at the low speed and transmits the collected images to the computer 150. The operator of the computer 150 determines (e.g., counts) the number of light pixels or dark pixels in the Y direction in a longitudinal spacing distance on the target 322. In Figure 3 In the embodiment shown, the Y direction is perpendicular to the axis 360 .

[0059] The user then sets the motor controller 340 to rotate the drum 320 at a high speed. The high speed may be in the range of 50 to 80 miles per hour (mph) (e.g., 65 mph). The high speed may represent Figure 1 The maximum speed of the vehicle 110 is determined by the image capture module 140 while the roller 320 is rotating at a high speed and the collected images are transmitted to the computer 150. The operator of the computer 150 determines (e.g., counts) the number of bright pixels or dark pixels in a pitch distance on the target 322 in the longitudinal direction Y. The high-speed and low-speed longitudinal pixel counts are compared with the horizontal pixel counts to determine whether the camera pixels represent the physical space equally in the horizontal and vertical directions. If the vertical pixel count is different from the horizontal pixel count, a different roller encoder rate can be programmed into the roller encoder 350, and the above process can be repeated to compare the effect of the new roller encoder rate on the pixel counts in the horizontal and vertical directions.

[0060] The drum encoder rate that produces the closest square pixel is then recorded and assigned to the image capture module 140. Figure 1 If the wheel diameter of the vehicle 110 is known, the vehicle encoder rate of the vehicle 110 can be calculated. The vehicle encoder rate is the number of electrical pulses generated by the vehicle encoder 120 when the shaft of the vehicle encoder 120 rotates one circle. The vehicle encoder rate is equal to Figure 1 = The wheel circumference of the vehicle 110 divided by the drum circumference of the drum 320 multiplied by the drum encoder rate. For example, if the wheel circumference of the vehicle 110 is 113.097 inches, the drum circumference of the drum 320 is 32.9867 inches, and the drum encoder rate is 32.9868 inches per revolution, then the vehicle encoder rate is 133.097 inches divided by 32.986 inches multiplied by 1715 pulses per revolution, which equals 5881 pulses per revolution. The user can program the vehicle encoder rate to Figure 1 In the vehicle encoder 120 of the system 100 , this may reduce the time and / or resources required to calibrate the image capture module 140 in the field.

[0061] although Figure 3 While a particular arrangement of image capture module 140, computer 150, network 160, fixture 310, drum 320, motor 330, motor controller 340, and drum encoder 350 is shown, the present disclosure contemplates any suitable arrangement of image capture module 140, computer 150, network 160, fixture 310, drum 320, motor 330, motor controller 340, and drum encoder 350. For example, motor 330 and motor controller 340 may be a single component. Image capture module 140, computer 150, fixture 310, drum 320, motor 330, motor controller 340, and drum encoder 350 may be physically or logically co-located with one another, in whole or in part.

[0062] although Figure 3 A particular number of image capture modules 140, computers 150, networks 160, fixtures 310, rollers 320, motors 330, motor controllers 340, and roller encoders 350 are shown, but the present disclosure contemplates any suitable number of image capture modules 140, computers 150, networks 160, rollers 310, motors 330, motor controllers 340, and roller encoders 350. For example, system 300 may include a first computer 150 communicatively coupled to image capture module 140 and a second computer 150 communicatively coupled to roller encoder 350. One or more components of system 100 may be configured using Figure 6 It is implemented by one or more components of a computer system.

[0063] Figure 4 An example method 400 for calibrating an image capture module in the field is shown. The method 400 begins at step 405. At step 410, a camera (e.g., Figure 2 The camera 210 of the image capture module 140 captures the target (e.g., Figure 1 The image capture module may be fixed to a vehicle (e.g., Figure 1 110), and the target may be fixed to the road (e.g., Figure 1 The target is perpendicular to the axis of the camera of the image capture module. The method 400 then moves from step 410 to step 415. The image captured by the camera of the image capture module can be displayed on a computer (e.g., a computer) communicatively coupled to the image capture module. Figure 1 on the computer 150).

[0064] At step 415 of method 400 , the operator determines the number of horizontal pixels within the lateral spacing distance of the target image. For example, the operator may observe the current focus of the camera under constant lighting conditions. If the contrast between the two pixels identifying the boundary between the bright and dark portions of the focused target is less than the contrast observed during bench testing, the operator may unlock the focus mechanism and adjust the focus until a satisfactory result is achieved. The focus mechanism is then locked. The operator may then count the number of bright or dark pixels within the lateral spacing distance of the target at the center of the camera's field of view. Method 400 then moves from step 415 to step 420 .

[0065] At step 420 of method 400, a lateral OPS is determined using the determined number of lateral pixels. For example, the operator may calculate the lateral OPS by dividing the pitch of target 322 (e.g., one inch) by the number of lateral pixels in the pitch area. Method 400 then moves from step 420 to step 425, where the lateral OPS is determined based on the number of lateral pixels programmed into the vehicle (e.g., Figure 1 of the vehicle 110) (e.g., Figure 2 The vehicle encoder rate is determined by the lateral OPS in the vehicle encoder 120). The vehicle encoder rate is equal to Figure 1 The wheel circumference of vehicle 110 is divided by the lateral OPS. The vehicle encoder has been set to an initial vehicle encoder rate, which was determined during the bench calibration process or arbitrarily. If the calculated vehicle encoder rate is different from the initial vehicle encoder rate previously programmed into the vehicle encoder, the calculated encoder rate is programmed into the vehicle encoder. Method 400 then moves from step 425 to step 430.

[0066] At step 430, the camera of the image capture module captures a second image of the target as the vehicle moves forward or backward over the target. For example, a train operator may move one or more parts of the train (e.g., a locomotive) along a railroad track so that the image capture module attached to the train passes over the target secured to the railroad track. Method 400 then moves from step 430 to step 435.

[0067] At step 435 of method 400, the operator determines the number of longitudinal pixels within a longitudinal spacing distance of the second image of the target. Method 400 then moves from step 440 to step 445, where the operator determines whether the number of transverse pixels in the first image matches the number of longitudinal pixels in the second image. If the number of transverse pixels in the first image matches the number of longitudinal pixels in the second image, method 400 moves from step 440 to step 445, where the operator determines, based on the comparison, that the image capture module is calibrated.

[0068] If, at step 440, the operator determines that the number of horizontal pixels in the first image is different from the number of vertical pixels in the second image, method 400 moves from step 440 back to step 425, where the operator adjusts the vehicle encoder rate to account for the difference and programs the new vehicle encoder rate into the vehicle encoder. Steps 425 to 440 are repeated until the number of horizontal pixels in the first image matches the number of vertical pixels in the third image (or fourth image, etc., as needed). When the number of horizontal and vertical pixels matches, method 400 moves from step 440 to step 445, where the operator determines, based on the comparison, that the image capture module is calibrated. Method 400 then moves from step 445 to step 450, where method 400 ends.

[0069] Can Figure 4 The method 400 shown may be modified, added to, or omitted. The method 400 may include more, fewer, or other steps. For example, the method 400 may include programming an initial vehicle encoder rate into the vehicle encoder. As another example, the method 400 may include activating a camera of an image capture module. The steps may be performed in parallel or in any suitable order. Although discussed as specific components performing the steps of the method 400, any suitable component may perform any step of the method 400.

[0070] Figure 5 An example method 500 for gantry calibration of an image capture module is shown. The method 500 begins at step 505. At step 510, a camera (e.g., Figure 2 the camera 210 of the image capture module 140), the roller (eg, Figure 3 The roller 320 in the Figure 3 The motor 330) is attached to a fixture (e.g., Figure 3 The method 500 then moves from step 510 to step 515, where the target (e.g., Figure 3 The target 322 is fixed to the drum. The target is connected to the drum encoder (e.g. Figure 3 The image capture module 140 is coaxially and synchronously positioned with the drum encoder 350. The image capture module is mounted in a fixture with a fixed working distance between the camera and the target. This working distance is nominal and may vary slightly between different vehicles using the image capture module 140. Method 500 then moves from step 515 to step 520.

[0071] At step 520, the camera captures a first image of the target. The camera may be connected to a computer (e.g., Figure 3The first image may be an image located in the center of the camera's field of view, as viewed by an operator using the computer. Method 500 then moves from step 520 to step 525, where the number of horizontal pixels within the horizontal pitch distance of the target image is determined. For example, the operator may use the first image displayed on the computer to calculate the number of bright pixels or dark pixels within the horizontal pitch distance of the target at the center of the camera's field of view. Method 400 then moves from step 525 to step 530.

[0072] At step 530 of method 500, a lateral OPS is determined using the determined number of lateral pixels. The lateral OPS is calculated by dividing the pitch of target 322 (e.g., one inch) by the number of lateral pixels in the pitch area. Method 500 then moves from step 530 to step 535, where the drum encoder rate is programmed into the drum encoder of the drum (e.g., Figure 3 The drum encoder rate is equal to the circumference of the drum 320 divided by the cross-machine OPS. Method 500 then moves from step 535 to step 540, where the drum encoder rate is programmed into the drum encoder. In some embodiments, the drum encoder is programmed with an integer value representing the drum encoder rate. Method 500 then moves from step 540 to step 545.

[0073] At step 545 of method 500, the motor controller is set to rotate the drum at a low speed (e.g., 10 mph). Method 500 then moves from step 545 to step 550, where the camera of the image capture module captures one or more images of the target while the drum is rotating at the low speed. Method 500 then moves from step 550 to step 555, where the number of longitudinal pixels within a longitudinal pitch distance of each image is determined. For example, each image can be displayed on a computer, and an operator can count the number of dark pixels or light pixels within a pitch distance in a longitudinal section of each image. Method 500 then moves from step 555 to step 560.

[0074] At step 560, the motor controller is set to rotate the drum at a high speed (e.g., 65 mph). The method 500 then moves from step 560 to step 565, where the camera of the image capture module captures one or more images of the target while the drum is rotating at the high speed. The method 500 then moves from step 565 to step 570, where a plurality of longitudinal pixels within a longitudinal pitch distance of each image are captured while the drum is rotating at the high speed. For example, each image can be displayed on a computer, and an operator can count the number of dark pixels or light pixels within a pitch distance in a longitudinal section of each image. The method 500 then moves from step 570 to step 575.

[0075] At step 575, the operator determines whether the number of horizontal pixels in the first image matches the number of vertical pixels in the images captured when the drum was rotating at low and high speeds. If the number of horizontal pixels in the first image matches the number of vertical pixels in the low / high speed images, the method 500 moves from step 575 to step 580, where the vehicle encoder rate is calculated using the drum encoder rate. The vehicle encoder rate is equal to Figure 1 The wheel circumference of the vehicle 110 is divided by Figure 3 The drum circumference of the drum 320 is then multiplied by the drum encoder rate. The method 500 then moves from step 580 to step 585, where the method 500 ends.

[0076] If, at step 575, the number of horizontal pixels in the first image is different from the number of vertical pixels in the low-speed / high-speed image, method 500 moves from step 575 back to step 540, where the roller encoder rate is adjusted to account for the difference. The adjusted roller encoder rate is programmed into the roller encoder. Steps 540 through 575 are repeated until the number of horizontal pixels in the first image matches the number of vertical pixels in the low-speed / high-speed image. When the number of horizontal and vertical pixels matches, method 500 moves from step 575 to step 580, where the vehicle encoder rate is calculated using the adjusted roller encoder rate. Method 500 then moves from step 580 to step 585, where method 500 ends.

[0077] Can Figure 5 Method 500 may include more, fewer, or other steps. For example, method 500 may include activating a camera of an image capture module. Steps may be performed in parallel or in any suitable order. For example, although specific components are discussed as performing the steps of method 500, any suitable component may perform any step of method 500. For example, one or more steps of method 500 may be automated (e.g., by Figure 3 150 executes).

[0078] Figure 6 An exemplary computer system is shown that can be used by the systems and methods described herein. For example, Figure 1 system 100 and / or Figure 3 One or more components of system 300 (e.g., computer 150) may include one or more interfaces 610, processing circuitry 620, memory 630, and / or other suitable elements. Interface 610 receives input, sends output, processes input and / or output, and / or performs other suitable operations. Interface 610 may include hardware and / or software.

[0079] The processing circuit 620 performs or manages the operation of the component. The processing circuit 620 may include hardware and / or software. Examples of processing circuits include one or more computers, one or more microprocessors, one or more applications, etc. In certain embodiments, the processing circuit 620 executes logic (e.g., instructions) to perform actions (e.g., operations), such as generating outputs from inputs. The logic performed by the processing circuit 620 may be encoded in one or more tangible, non-transitory computer-readable media (e.g., memory 630). For example, the logic may constitute a computer program, software, computer-executable instructions, and / or instructions capable of being executed by a computer. In certain embodiments, the operations of the embodiments may be performed by one or more computer-readable media that store, embody, and / or encode a computer program and / or have a stored and / or encoded computer program.

[0080] Memory 630 (or memory unit) stores information. Memory 630 may include one or more non-transitory, tangible, computer-readable and / or computer-executable storage media. Examples of memory 630 include computer memory (e.g., RAM or ROM), mass storage media (e.g., a hard disk), removable storage media (e.g., a compact disk (CD) or digital video disk (DVD)), databases and / or network storage (e.g., a server), and / or other computer-readable media.

[0081] Embodiments of the present disclosure relate to systems and methods for capturing a first image of a target by a camera of an image capture module. The image capture module and a drum are attached to a fixture, and the target is attached to the drum. The method also includes the steps of determining a number of lateral pixels in a lateral pitch distance of the target image, determining a lateral object pixel size based on the number of lateral pixels, and determining a drum encoder rate based on the lateral object pixel size. The drum encoder rate is programmed into a drum encoder attached to the drum. The method also includes the steps of capturing a second image of the target by the camera of the image capture module as the target rotates about an axis of the drum, determining a number of longitudinal pixels in a longitudinal pitch distance of the second image, and comparing the number of lateral pixels to the number of longitudinal pixels.

[0082] Here, the computer-readable non-transitory storage medium may include one or more semiconductor-based or other integrated circuits (ICs) (e.g., field programmable gate arrays (FPGAs) or application-specific ICs (ASICs)), hard disk drives (HDDs), hybrid hard disk drives (HHDs), optical disks, optical disk drives (ODDs), magneto-optical disks, magneto-optical drives, floppy disks, floppy disk drives (FDDs), magnetic tape, solid-state drives (SSDs), RAM drives, secure digital cards or drives, any other suitable computer-readable non-transitory storage medium, or any suitable combination of two or more thereof (as applicable). Where appropriate, the computer-readable non-transitory storage medium may be volatile, non-volatile, or a combination of volatile and non-volatile.

[0083] As used herein, unless expressly stated otherwise or the context indicates otherwise, "or" is inclusive, not exclusive. Thus, as used herein, "A or B" means "A, B, or both," unless expressly stated otherwise or the context indicates otherwise. Furthermore, unless expressly stated otherwise or the context indicates otherwise, "and" is both conjunctive and plural. Thus, as used herein, "A and B" means "A and B, jointly or severally," unless expressly stated otherwise or the context indicates otherwise.

[0084] The scope of the present disclosure includes all changes, substitutions, variations, alterations and modifications to the example embodiments described or illustrated herein that would be understood by a person of ordinary skill in the art. The scope of the present disclosure is not limited to the example embodiments described or illustrated herein. In addition, although the present disclosure describes and illustrates the various embodiments herein as including specific components, elements, features, functions, operations or steps, any of these embodiments may include any combination or arrangement of any components, elements, features, functions, operations, or steps described or illustrated anywhere in this document that would be understood by a person of ordinary skill in the art. In addition, in the appended claims, references to a device or system or component of a device or system that is suitable for, arranged, capable of, configured to, enabled, operable or operable to perform a specific function encompass the device, system, component, regardless of whether it or the specific function is activated, turned on or unlocked, as long as the device, system or component is so suitable, arranged, capable, configured to, enabled, operable or operable. In addition, although the present disclosure describes or illustrates specific embodiments as providing specific advantages, specific embodiments may not provide, partially or fully provide these advantages.

Claims

1. A system for on-site calibration of an image capture module, comprising: a vehicle having a light beam for directing components of said system for field calibration while said vehicle is in motion; as well as an image capture module, operatively coupled to the light beam, comprising: a camera configured to capture images of a target disposed proximate to the railroad track; and a memory configured to store the captured image of the target; The image capture module is configured to perform on-site calibration of the image capture module by the following steps: capturing a first image of a target via the camera; initializing a vehicle encoder operatively coupled to the vehicle with a vehicle encoder rate; adjusting the contrast between two pixels identifying a boundary between a bright portion and a dark portion of the object; comparing the number of horizontal pixels to the number of vertical pixels; and The vehicle encoder rate is adjusted until the number of horizontal pixels matches the number of vertical pixels.

2. The system of claim 1, wherein the target comprises a calibration pattern.

3. The system of claim 2, wherein the calibration pattern has a pitch between 0.375 inches and 2.0 inches. The system of claim 2 , wherein the calibration pattern comprises cells having unequal aspect ratios. 5 . The system of claim 1 , wherein the vehicle encoder rate is the number of electrical pulses generated by the vehicle encoder in one rotation of a shaft of the vehicle encoder. The system of claim 1 , wherein the contrast is adjusted by unlocking the focus.

7. The system of claim 1, wherein the vehicle encoder is a timing device for measuring axle rotation.

8. The system of claim 1, wherein the vehicle encoder is a rotary encoder.

9. A method for field calibration of an image capture module, comprising: capturing, via an image capture module operatively coupled to the light beam of the vehicle, a first image of a target disposed proximate to a railroad track; initializing a vehicle encoder operatively coupled to the vehicle with a vehicle encoder rate; capturing, via the image capture module, a second image of the target as the vehicle moves past the target; receiving an image adjustment for adjusting a contrast between two pixels identifying a boundary between a bright portion and a dark portion of the object; Compare the number of horizontal pixels to the number of vertical pixels; as well as The vehicle encoder rate is adjusted until the number of horizontal pixels matches the number of vertical pixels.

10. The method of claim 9, wherein the target comprises a calibration pattern. The method of claim 10 , wherein the calibration pattern has a pitch between 0.375 inches and 2.0 inches. The method of claim 10 , wherein the calibration pattern comprises cells having unequal aspect ratios.

13. The method of claim 9, wherein the vehicle encoder rate is the number of electrical pulses generated by the vehicle encoder in one rotation of a shaft of the vehicle encoder. The method of claim 9 , wherein the contrast is adjusted by unlocking focus.

15. The method of claim 9, wherein the image capture module comprises a camera configured to capture the image.

16. The method of claim 9, wherein the image capture module comprises a plurality of cameras configured to capture images of the target from different angles.

17. A system for calibrating an image capture module, comprising: a camera array for acquiring at least one image sequence of each item; a memory for storing acquired images and information for each image; as well as A processor configured to calibrate the image capture module by performing the following steps: capturing, by the camera array, a first image of a target attached to the drum; determining a number of lateral pixels in a lateral spacing distance of a first image of the target; determining a horizontal object pixel size based on the number of horizontal pixels; determining a drum encoder rate based on the lateral object pixel size, wherein the drum encoder rate is programmed into a drum encoder attached to the drum; as well as A vehicle encoder rate is calculated based on the drum encoder rate.

18. The system of claim 17, further comprising capturing a second image of the target by a camera of the image capture module as the target rotates about the axis of the drum.

19. The system of claim 18, further comprising determining a number of vertical pixels in a vertical pitch distance of the second image.

20. The system of claim 19, further comprising comparing the number of horizontal pixels to the number of vertical pixels.

21. The system of claim 20, further comprising determining that the number of horizontal pixels matches the number of vertical pixels in response to comparing the number of horizontal pixels to the number of vertical pixels.

22. The system of claim 21 further comprising programming the vehicle encoder rate into a vehicle encoder attached to a wheel of the vehicle.

23. The system of claim 22, further comprising: capturing a third image of the object by a camera of the image capture module while the object rotates about the axis of the drum; determining the number of longitudinal pixels in the longitudinal spacing distance of the third image; as well as The number of the horizontal pixels is compared with the number of the vertical pixels in the vertical pitch distance of the third image.

Images