Abstract:
Images from the video camera of a computer are compared over time, e.g., every few milliseconds, to determine from the pixel data if motion of the computer matches template motion associated with an earthquake P-wave. If so, a warning is generated, uploaded to a communication network, and propagated over the network to other computers.

Description:
I. FIELD OF THE INVENTION 
     The present application relates generally to using a video camera on a computer to provide early warning of an earthquake. 
     II. BACKGROUND OF THE INVENTION 
     Earthquake early warning systems can provide a few to a few tens of seconds warning prior to damaging ground shaking, depending on the distance of the warned entity from the epicenter. Essentially, early warning systems use accelerometers to detect the initial primary wave (P-wave) of a quake, which typically is perceived as a jolt and which precedes the more damaging secondary waves (S-waves) because the P-wave travels faster. 
     Although providing only a short window of warning, an early warning system nonetheless can allow for short-term mitigation including slowing and stopping of transportation systems, switching industrial and utility systems to a safe mode, and taking personal protective measures. In other words, while a few seconds may not sound like much, it is enough time for school children to dive under their desks, gas and electric companies to shut down or isolate their systems, phone companies to reroute traffic, airports to halt takeoffs and landings, and emergency providers to pinpoint probable trouble areas. Such actions can save lives and money. As understood herein, it is possible to leverage existing infrastructure to provide such early warning of an impending earthquake. 
     SUMMARY OF THE INVENTION 
     Accordingly, a computer includes a housing, a processor in the housing, and a video camera coupled to the housing and communicating with the processor. The processor executes logic to use first image information generated by the video camera at a first time and at least second image information generated by the video camera at a second time to render a motion output. Based at least in part on the motion output, an earthquake detection signal (EDS) indicating that an earthquake is impending is selectively generated. 
     In some implementations the processor generates the EDS responsive to a determination that the comparison indicates oscillating motion within a predetermined time period. If desired, responsive to a determination that the motion output indicates an earthquake, the processor uploads the EDS to a communication network for transfer thereof to other computers. In specific embodiments the computer is a first computer, the EDS is a first EDS, and an earthquake alarm is generated in response to the first EDS only if at least a second computer generates a second EDS within a predetermined period of the first EDS to validate the first EDS. 
     The motion output may be compared to a template and the EDS generated responsive to a determination of a substantial match between the motion output and the template. The motion output may represent horizontal motion relative to the Earth&#39;s surface and/or vertical motion relative to the Earth&#39;s surface. In example non-limiting embodiments the motion output is derived from subpixel motion estimation. 
     In another aspect, a method includes generating a video image and using a first computer, determining motion within the image. The method further includes determining whether the motion within the image fits at least one earthquake criterion. An indication that an earthquake is impending is presented on a computer display responsive to a determination that the motion within the image fits the at least one earthquake criterion. 
     In another aspect, a computer includes a processor receiving image signals from a video camera, and a non-transitory computer storage medium accessible to the processor and bearing logic. The logic is executed by the processor to selectively determine an earthquake is impending responsive to motion of at least one object in the image signals. An earthquake detection signal (EDS) is generated responsive to a determination that an earthquake is impending. 
     The details of the present invention, both as to its structure and operation, can best be understood in reference to the accompanying drawings, in which like reference numerals refer to like parts, and in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of an example system in accordance with present principles; 
         FIG. 2  is a flow chart of example logic for providing an earthquake message and/or warning; and 
         FIG. 3  is an example non-limiting earthquake wave template. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring initially to  FIG. 1 , a system  10  is shown that includes a computer  12  such as a laptop or notebook computer, a PC, or a personal digital assistant that in turn typically has portable lightweight plastic housing  14  bearing a digital processor  16 . The processor  16  can control a visual display  18  and an audible display  20  such as one or more speakers. 
     To undertake present principles, the processor  16  may access one or more computer readable storage media  22  such as but not limited to disk-based or solid state storage. In example non-limiting embodiments, the media  22  may store various software modules, including, for example, a module bearing logic executable by the processor to undertake present principles. 
     A video camera  24  may also be coupled to the housing  14 . The camera  24 , which may include, e.g., a charge-coupled device (CCD), sends signals representing images to the processor  16 . Also, the processor  16  may communicate with another like computer  26  and/or with an Internet server  28  having a server processor  30  and server storage medium  32  using a communications interface  34 , such as a wired or wireless modem or telephone transceiver. The computers  12 ,  26  may each execute portions of the logic herein and the server  28  likewise may execute certain portions such as the below-described validation logic. One or more input devices such as a keypad  36  and point and click device  38  may be provided on the computer  12  (and likewise on the computer  26  as shown) to provide a means for inputting user commands to the processor  16 . 
     Now referring to  FIG. 2 , at block  40  the processor  16  receives pixel information from the camera  24  at time “t 0 ”, and then at block  42  receives additional pixel information at one or more subsequent times, i.e., times “t 1 ”, “t 2 ”, “t 3 ”, “t 4 ”, . . . . The times are closely staggered, e.g., are a few milliseconds or even a few microseconds apart. 
     Proceeding to block  44  the information generated by the video camera  24  at the various times is used to determine motion. By way of non-limiting example, a macro block of pixels in the image may be used or image recognition principles may be used to identity an image in front of the camera, and the image information from the succession of times is used to determine relative motion of the image over time within the camera&#39;s field of view. This may be as simple as identifying a human face, a desk, or other recognizable object within the image and then noting changes in that object&#39;s position within the image over the times “t 0 ”, . . . “t 4 ” to determine its motion. The motion may represent vertical motion of the object relative to the Earth&#39;s surface, and/or horizontal motion of the object in the north-south dimension, and/or horizontal motion of the object in the east-west dimension. 
     Or, the motion of an object in the image may be determined using derived subpixel motion estimation techniques. Non-limiting examples of such techniques are described in Suh et al.,  Fast Sub - pixel Motion Estimation Techniques Having Lower Computational Complexity,  50 IEEE Transactions on Consumer Electronics 3 (August 2004) and Argyriou et al.,  A Study of Sub - pixel Motion Estimation Using Phase Correlation, available at www.macs.hw.ac.uk/bmvc 2006/papers/328.pdf. Both of the above documents appear in the present file history and both are incorporated herein by reference. 
     Based on the motion determined at block  44 , an earthquake detection signal (EDS) indicating that an earthquake is impending is selectively generated. In one example, this may be done by proceeding to block  46  to compare the detected motion with a template of earthquake-caused motion. An example template is discussed further below. If, at decision diamond  48 , it is determined that the detected motion does not match the template within a predetermined threshold, the logic ends at state  50 , but when the detected motion substantially matches the template a quake is indicated. 
     In some embodiments, prior to generating an alarm, if desired the logic may move from a positive test result at decision diamond  48  to block  52 , wherein verification of an earthquake is obtained by accessing a second (typically nearby) computer such as the computer  26  shown in  FIG. 1 . The motion detected by the first computer (e.g., the computer  12 ) may also be sent to the second computer  26  at block  54  to allow both computers to independently verify an earthquake. Yet again, both computers may send their determinations to the server  28 , which may conduct the verification steps and send the results back to the computers  12 ,  26 . Signals from more than two computers may be used, if desired, to undertake the verification. 
     In other words, motion signals from two or more computers can be cross-correlated to reject false alarms. Similarities (or lack thereof) in signals received from different computers can be identified and compared, and a determination made that the signals represent an earthquake if their patterns match. On the other hand, for example, if one computer detects movements not from an earthquake but from a moving table, its motion signal would not cross-correlate with any other computer signals and so it would be rejected as an earthquake indication. 
     In any case, if the verification steps indicate that both computers determine that they have detected earthquake-like motion at decision diamond  56 , the logic moves to block  58  to generate an audible and/or visible alarm (on, e.g., the display  18 /speaker  20 ) representing a message that an earthquake is impending. In the case wherein no verification is undertaken the logic flows immediately from a positive test at decision diamond  48  to block  58 . 
       FIG. 3  shows an example template  60  against which detected motion may be compared. The amplitude or velocity of the y-axis may be in the vertical plane or east-west or north-south horizontal planes as discussed above. Indeed, three comparisons, one for each of the above dimensions, may be undertaken and only if all three, or two of the three, match the template is an EDS generated. 
     As shown, the earliest wave-like form is the P-wave, followed by the S-wave. The comparison at block  46  in  FIG. 2  may thus compare the frequency and amplitude decay of the detected motion of the imaged object with that of the template and if, for example, a match within a threshold is determined, an EDS is generated. In other words, an EDS can be generated responsive to a determination of oscillating motion of the imaged object within a predetermined time period, with a predetermined amplitude decay. 
     While an earthquake will affect not just the computer  12  with camera  24  but also objects within the camera&#39;s field of view, owing to structural differences, material differences, mounting differences, etc., relative motion nonetheless can be expected between the camera and objects within its field of view. 
     The alarm and/or message generated at block  58  may further indicate, based on the characteristics of the P-wave, the expected time until the arrival of the S-wave. For example, a higher P-wave frequency may indicate a sooner S-wave arrival while a lower P-wave frequency may indicate a later S-wave arrival, and a message of such may be generated. Yet again, the expected severity of the S-wave may be included in the message/warning at block  58  based on the frequency or other characteristic of the P-wave, with, e.g., a higher frequency indicating a stronger S-wave and a lower frequency indicating a weaker S-wave. 
     While the particular USING COMPUTER VIDEO CAMERA TO DETECT EARTHQUAKE is herein shown and described in detail, it is to be understood that the subject matter which is encompassed by the present invention is limited only by the claims.