Abstract:
Apparatus for inspecting a vehicle in order to determine whether portions of the vehicle have been altered to conceal contraband or explosives. The apparatus captures an image of an area of a vehicle that should not be altered from a known configuration and compares the image to a reference image of the area as it should appear if it is unaltered. If the captured image and the reference image match, the vehicle is considered unaltered, and hence safe to pass. If the captured image and the reference image do not match, the vehicle is identified as likely to have been altered, and hence a candidate for further inspection. An alert is produced if at least one such difference is found.

Description:
TECHNICAL FIELD  
       [0001]     This invention relates to the use of digital imaging for security applications.  
       BACKGROUND OF THE INVENTION  
       [0002]     Security checks, such as those performed at border crossings and entry points to high-risk areas, e.g., bridges, tunnels, government owned buildings, airports, harbors, etc., often involve stopping a vehicle, e.g., an automobile, airplane, train, or boat, and inspecting it to determine whether it contains contraband or explosives. For areas of the vehicle not easily visible by the inspector, e.g., the underside of a vehicle, use may be made of a mirror attached to an extended rigid handle, e.g., a long rod or a staff, to enable the inspector to inspect such areas.  
         [0003]     Unfortunately, such a mirror only provides a limited view of the total underside of the vehicle. Also disadvantageously, the inspector has no way to compare what is being seen to what is appropriate to be present for the particular vehicle being inspected. Further disadvantageously, the inspectors view may be limited by the illumination that is available underneath the vehicle.  
       SUMMARY OF THE INVENTION  
       [0004]     We have recognized that the problems of the prior art of vehicle inspection may be avoided by automatically a) inspecting areas of a vehicle that should not be altered and b) determining whether such areas have been altered. This may be achieved, in accordance with an aspect of the invention, by an apparatus that i) captures an image of an area of a vehicle that should not be altered from a known configuration and ii) compares the image to a reference image of the area as it should appear if it is unaltered. If the captured image and the reference image match, the vehicle is considered unaltered, and hence safe to pass. If the captured image and the reference image do not match, the vehicle is identified as likely to have been altered, and hence a candidate for further inspection.  
         [0005]     In one embodiment of the invention, an automatic vehicle inspection system captures an image of the underside of a vehicle at a checkpoint. The image may be captured using, for example, a scanner built into, or placed on, the floor over which the vehicle is driven. An identifier of the vehicle, e.g., the vehicle&#39;s license plate number and/or the vehicle identification number (VIN), is obtained and used to obtain a stored copy of a reference image of the underside of the vehicle from a database. The database may be located local to, or remote from, the vehicle inspection system.  
         [0006]     The vehicle inspection system performs an image matching process to compare the captured image of the vehicle&#39;s underside to the reference image to determine whether the images match. If the captured image and the reference image match, the vehicle is considered unaltered, and hence safe to pass through the checkpoint. If the captured image and the reference image do not match, the vehicle is identified as likely to have been altered, and hence not safe to pass, but instead to be a candidate for further inspection. In the latter case, areas of difference between the captured image of the vehicle&#39;s underside and the reference image may be identified, e.g., highlighted, and an alert is produced so that an inspector may investigate such differences.  
         [0007]     Advantageously, when using the automatic vehicle inspection system an inspection may be made of the total underside of a vehicle, rather than merely a portion thereof, as was done in the prior art. Furthermore, the same approach can be used for other areas of a vehicle that should remain unaltered after a reference image is taken, e.g., the engine compartment.  
         [0008]     The image capture portion of the automatic vehicle inspection system typically can capture an adequate image with less light than is required by a human being to make a comparable inspection. Also, the automatic vehicle inspection system may be able to operate with wavelengths of light that are not visible to human beings. Thus, the automatic vehicle inspection system does not need an environment that has adequate lighting for visual perception by a human being. Further advantageously, the automatic vehicle inspection system does not depend upon a human operator to determine whether areas of the vehicle that should not be altered have been altered, and so it is less prone to errors than a human-based inspection system. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  shows an exemplary automatic vehicle inspection system arranged in accordance with the principles of the invention; and  
         [0010]      FIG. 2  shows a flow chart for a method of operating an automatic vehicle inspection system arranged in accordance with the principles of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0011]      FIG. 1  shows an exemplary automatic vehicle inspection system  10  arranged in accordance with the principles of the invention. Shown in  FIG. 1  are image capture system  30 , vehicle identification device  35 , processor  40 , monitor  43 , and database  80 . Also, shown in  FIG. 1  is vehicle  20 , a vehicle to be inspected at a checkpoint at which automatic vehicle inspection system  10  is implemented.  
         [0012]     Image capture system  30  captures at least one image of at least one area of a vehicle that should remain unaltered, e.g., the underside of a vehicle. To that end, image capture system  30  is positioned so that it can capture an image of the area of interest of vehicle  20 . In the embodiment of the invention shown in  FIG. 1 , image capture system  30  is located in the floor over which vehicle  20  is driven, thereby positioning it to capture an image of the underside of vehicle  20 . Image capture system  30  may capture an image of vehicle  20  when it is stopped at the checkpoint, or while vehicle  20  is moving through the checkpoint.  
         [0013]     Image capture system  30  may be a digital camera, scanner, machine vision system, or the like. Image capture system  30  may be such that it can capture an image with less light than is required by a human being to make an inspection. Alternatively, image capture system  30  may be able to operate with wavelengths of light that are not visible to human beings.  
         [0014]     Image capture system  30  may have a built-in controller or processor  40  may control it. The output of image capture system  30  is supplied to processor  40 .  
         [0015]     Vehicle identification device  35  is a device capable of obtaining information that identifies the vehicle being inspected. The vehicle identifying information may be obtained, for example, a) from character information written on the vehicle; b) from coded information printed on the vehicle, e.g., bar code or other pattern information; c) from a radio frequency identification (RFID) type tag in the vehicle; d) from a port on the vehicle, such as may be connected to the vehicle&#39;s computer; or e) from the shape and details of the exterior of the vehicle.  FIG. 1  shows two different possible locations, location  37  and location  39 , for vehicle identification device  35 . The particular location actually employed depends upon the particular implementation as described hereinbelow.  
         [0016]     As noted, in one embodiment of the invention shown in  FIG. 1 , vehicle identification device  35  may obtain the vehicle identifying information from characters affixed to vehicle  20 . For example, vehicle identification device  35  may capture an image of at least one area of vehicle  20  that is expected to contain characters, such as the license plate area or an area known to contain the manufacturer&#39;s specified vehicle identification number (VIN), i.e., a unique serial number, of vehicle  20 . To this end, vehicle identification device  35  may be located at location  37 , so that a digital image of the rear license plate area of vehicle  20  is obtained, since not all government licensing entities require a vehicle to have a license plate in front. Alternatively, vehicle identification device  35  may be located at location  39 , so that an image of an area on the inside of the windshield where the VIN is conventionally located, e.g., printed on a tag, may be obtained.  
         [0017]     Similar to image capture system  30 , vehicle identification device  35  may be a digital camera, scanner, machine vision system, or the like. Also, similar to image capture system  30 , vehicle identification device  35  may be able to capture an image with less light than is required by a human being to perform an adequate inspection, or it may be able to operate with wavelengths of light that are not visible to a human being.  
         [0018]     An image captured by vehicle identification device  35  may be analyzed using well-known character recognition techniques to determine the characters contained in the area. The image area may be analyzed by vehicle identification device  35  itself, or in conjunction with, or wholly by processor  40 . The resulting character string is stored by processor  40 .  
         [0019]     In another embodiment of the invention, vehicle identification device  35  is a bar code scanner that scans a bar code pattern printed on the vehicle. The scanned pattern is then converted to a corresponding digital representation, e.g., the characters corresponding to the bar code.  
         [0020]     In a further embodiment of the invention, vehicle identification device  35  is a RFID tag reader, which obtains an identifying code by use of an antenna that uses radio frequency waves. More specifically, vehicle identification device  35  may transmit a radio signal that activates transponder/tag  25  located in vehicle  20 . When activated, transponder/tag  25  transmits back to the antenna of vehicle identification device  35  data which includes the identifying code. In such an embodiment of the invention, vehicle identification device  35  may be located at location  35 .  
         [0021]     In yet another embodiment of the invention, vehicle identification device  35  is capable of obtaining an image of a portion of a vehicle, e.g., part of the exterior of vehicle  20 . Using image matching techniques the image area may be analyzed by vehicle identification device  35  itself, or in conjunction with, or wholly by processor  40 , to determine the year, make, and model of vehicle  20  from the captured image.  
         [0022]     Note that although two possible locations for vehicle identification device  35  have been shown, other locations are possible as well. Based on the foregoing, those of ordinary skill in the art will readily be able to place vehicle identification device  35  at an appropriate location to best capture the information of the type to be obtained by any particular embodiment of vehicle identification device  35 .  
         [0023]     Processor  40  may be any type of processor. Processor  40  can perform image matching techniques so as to determine whether areas of a captured image and a reference image match. Processor  40  should not be construed to refer exclusively to hardware capable of executing software, and may implicitly include, without limitation, digital signal processor (DSP) hardware, network processor, application specific integrated circuit (ASIC), field programmable gate array (FPGA), read only memory (ROM) for storing software, random access memory (RAM), and non volatile storage. The functions of processor  40  may be provided by a single dedicated processor, by a single shared processor, or by a plurality of individual processors, some of which may be shared.  
         [0024]     In one embodiment of the invention, processor  40  may be a conventional computer that has software to perform image matching available to it. The image matching may be flexible enough to ignore minor differences between the captured image and the reference image, such as vendor names on replacement parts installed after delivery of a vehicle to its owner, and to yet consider such images to match. Also, processor  40  may be able to display, e.g., on monitor  43 , the differences identified by the image matching.  
         [0025]     Database  80  stores reference images of vehicles as they should appear if the vehicle is unaltered. The reference images are organized so that when information identifying a particular vehicle, or type of vehicle, is presented, the corresponding reference image may be retrieved. Thus, for example, database  80  may store a reference image of the underside of vehicle  20 , and this stored reference image will be retrieved in response to presentation of an identifier of vehicle  20 . The identifier may be any identifying information capturable by vehicle identification device  35 . Database  80  may be stored local to processor  40 , or remote therefrom.  
         [0026]     The reference images used to populate database  80  may be supplied by a) a vehicle manufacturer, which could supply such an image immediately after manufacturing the vehicle; or b) a vehicle dealer, e.g., which could supply such an image before delivery of the vehicle to its buyer, so that the image may be taken after post manufacture vehicle customization. Also, special scanning stations may be provided by, for example, the government or security organizations, to capture, and supply for storage in database  80 , images of vehicles already in use by their owners.  
         [0027]     Those of ordinary skill in the art will readily be able to select processors, databases, vehicle identification devices and image capture systems appropriate for use in any particular implementation of an automatic vehicle inspection system.  
         [0028]     Advantageously, when using the automatic vehicle inspection system  10  an inspection may be made of the total underside of vehicle  20 , rather than merely a portion thereof, as was done in the prior art. Furthermore, the same approach can be used for other areas of a vehicle that should remain unaltered after a reference image is taken, e.g., the engine compartment. Also, advantageously, vehicle inspection system  10  can operate under lighting conditions not amenable to human inspections. Further advantageously, automatic vehicle inspection system  10  does not depend upon a human operator to determine whether areas of vehicle  20  that should not be altered have been altered, and so it is less prone to errors than a human-based inspection system.  
         [0029]      FIG. 2  shows a flow chart of a process for performing a vehicle inspection in accordance with the principles of the present invention. The process is entered in step  200  when a vehicle approaches a checkpoint equipped with an automatic vehicle inspection system, such as is shown in  FIG. 1 .  
         [0030]     In step  210  ( FIG. 2 ), a vehicle identifier, e.g., i) a license plate number; ii) a VIN; iii) a RFID tag number; iv) a bar code; v) the year, make and model type of a vehicle; or other information identifying the vehicle, is obtained. This step may be performed when the vehicle is positioned within range of vehicle identification device  35  ( FIG. 1 ), and possibly in conjunction with processor  40 .  
         [0031]     In step  220  ( FIG. 2 ), an image of an area of the vehicle that should not have been altered since a reference image of that area was stored, e.g., the underside or engine compartment, is taken when the vehicle is positioned to facilitate the taking of such an image, e.g., by image capture system  30  ( FIG. 1 ). Next, in step  230  ( FIG. 2 ), a reference image of the area of the vehicle captured in step  220  is obtained. The reference image is obtained as a function of the vehicle identifier obtained in step  210 . The reference image may be obtained from database  80  ( FIG. 1 ).  
         [0032]     In step  240  ( FIG. 2 ), the captured image of the vehicle is compared with the reference image of the vehicle to determine if there are any differences. Thereafter, conditional branch point  250  tests to determine if any differences were detected when doing the comparison in step  240 . If the test result in step  250  is YES, indicating that the captured image and the reference image match, and therefore the vehicle is considered unaltered, and hence safe to pass through the checkpoint, control passes to step  260 , in which a signal indicating that the vehicle is safe to pass through the checkpoint is generated. The process is then exited in step  290 . If the test result in step  250  is NO, indicating that the captured image and the reference image do not match, the vehicle is identified as likely to have been altered, and hence not safe to pass, but instead to be a candidate for further inspection. Therefore, control passes to step  270 , in which a signal indicating that the vehicle is not safe to pass through the checkpoint is generated. Control is then passed to step  280 .  
         [0033]     In optional step  280 , areas of difference between the captured image and the reference image may be pointed out, e.g., by drawing a circle around the area, placing pointers on the image showing the area of difference, highlighting the area of difference, or using other conventional display techniques. The reference image and the captured image may be displayed side by side on a monitor for the convenience of a human operator. Further, the operator may be able to manipulate the image, such as magnifying and/or rotating it to better see the change that was made to the vehicle.  
         [0034]     The process is exited in step  290 .  
         [0035]     Note that the signal indicating that the vehicle is safe to pass and/or the signal indicating that the vehicle is not safe to pass may be human perceivable.  
         [0036]     The foregoing merely illustrates the principles of the invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements, which, although not explicitly described or shown herein, embody the principles of the invention, and are included within its spirit and scope.