Position management device, position management system, position management method, and position management program

The position management device includes: a calculation unit that gives identification on an object being monitored to the object being monitored cyclically imaged, and calculates positional information of the object from an image of the object; a storage unit that associates the identification and an imaging time with the positional information, and stores these items; and a comparison unit that compares, with respect to the object, an absolute value of a difference between the positional information as of a current time and the positional information as of each of the imaging times one and two cycle(s) prior to the current time, as stored in the storage unit, with a predetermined reference value, and outputs the positional information as of the current time if the absolute value for at least one of the imaging times is less than the reference value.

This application is a National Stage Entry of PCT/JP2013/004030 filed on Jun. 28, 2013, which claims priority from Japanese Patent Application 2012-148404 filed on Jul. 2, 2012, the contents of all of which are incorporated herein by reference, in their entirety.

TECHNICAL FIELD

The present invention relates to a position management device and the like which calculates positional information on an object being monitored from images taken by a monitoring camera.

BACKGROUND ART

A recent increased awareness of security and greater needs for IT (Information Technology) based on-site management have led to introduction of monitoring systems employing monitoring cameras into various places. These monitoring systems have a function to detect a position of an object being monitored by performing image analysis processing on images output by a monitoring camera and then utilizing the processing results.

As a technique related to positional detection of objects being monitored in such monitoring systems, PTL 1 discloses an apparatus which performs data processing on images taken by an infrared camera and a PTZ (Pan Tilt Zoom) camera which obtain moving images. This apparatus identifies a monitoring target, i.e. a person smoking while walking, then uses the PTZ camera to track the identified person who is smoking while walking.

In addition, PTL 2 discloses an apparatus which is capable of detecting the position of a person by precisely combining a plurality of sets of positional information on the person whose images have been taken by a plurality of monitoring cameras, even if these sets of positional information have a detection error.

In addition, PTL 3 discloses an apparatus which determines that an object i is identical to an object j if a difference between coordinates of a gravity center of the object i at a time k and coordinates of a gravity center of the object j at a time (k+1) is less than a predetermined value.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

The above-described apparatus according to PTL 1 tracks the object being monitored on the basis of image data taken by one infrared camera and one PTZ camera. Accordingly, there is a problem in that it is possible to fail to detect an accurate position of the object being monitored if either camera produces an erroneous output.

In addition, the above-described apparatus according to PTL 2 calculates the position of an object being monitored using image data taken by a plurality of monitoring cameras for the same object. There is a problem in that accuracy can possibly be significantly decreased during combination of sets of positional information which are output by a plurality of the monitoring cameras if any monitoring camera produces the erroneous output.

A primary objective of the present invention is to provide a position management device, a position management system, a position management method, and a position management program which solve the problems described above.

Solution to Problem

A position management device relevant to the present patent application includes: a calculation unit for giving identification information on an object being monitored to the object being monitored cyclically imaged by an imaging device, and for calculating positional information of the object being monitored from an image of the imaged object being monitored; a storage unit for associating the identification information of the object being monitored and an imaging time with the positional information, and for storing the identification information, the imaging time and the positional information, which are associated with each other; and a comparison unit for comparing, with respect to the object being monitored, an absolute value of a difference between a value of the positional information as of a current time and a value of the positional information as of each of the imaging times one cycle and two cycles prior to the current time, as stored in the storage unit, with a predetermined reference value, and for outputting the positional information as of the current time even if the absolute value of the difference for the imaging time one cycle prior to the current time is equal to or greater than the reference value, and if the absolute value of the difference for the imaging time two cycles prior to the current time is less than the reference value.

In another aspect for achieving the above-mentioned objective, a position management method of the present patent application includes: by an information processing apparatus, giving identification information on an object being monitored to the object being monitored cyclically imaged by an imaging device, and calculating positional information of the object being monitored from an image of the imaged object being monitored; by an information processing apparatus, associating the identification information of the object being monitored and an imaging time with the positional information, and storing the identification information, the imaging time and the positional information in a storage area; and by the information processing apparatus, comparing, with respect to the object being monitored, an absolute value of a difference between a value of the positional information as of a current time and a value of the positional information as of each of the imaging times one cycle and two cycles prior to the current time, as stored in the storage area, with a predetermined reference value, and outputting the positional information as of the current time even if the absolute value of the difference for the imaging time one cycle prior to the current time is equal to or greater than the reference value, and if the absolute value of the difference corresponding to the imaging time two cycles prior to the current time is less than the reference value.

In a further aspect for achieving the above-mentioned objective, a position management program relevant to the present patent application causes a computer to execute: a calculation processing of giving identification information on an object being monitored to the object being monitored cyclically imaged by an imaging device, and calculating positional information of the object being monitored from an image of the imaged object being monitored; a storage processing of associating the identification information of the object being monitored and an imaging time with the positional information, and storing the identification information, the imaging time and the positional information, which are associated with each other, in a storage area; and a comparison processing of, with respect to the object being monitored, comparing an absolute value of a difference between a value of the positional information as of a current time and a value of the positional information as of each of the imaging times one cycle and two cycles prior to the current time, as stored in the storage area, with a predetermined reference value, and outputting the positional information as of the current time even if the absolute value of the difference for the imaging time one cycle prior to the current time is equal to or greater than the reference value, and if the absolute value of the difference for the imaging time two cycles prior to the current time is less than the reference value.

Furthermore, in another aspect of the present invention, such position management program (a computer program) can also be implemented by a computer-readable nonvolatile storage medium.

Advantageous Effects of Invention

The present invention makes it possible to calculate, with high precision, positional information on an object being monitored from an image taken by a monitoring camera.

DESCRIPTION OF EMBODIMENTS

A first exemplary embodiment of the present invention will now be explained in detail with reference to the drawings.

First Exemplary Embodiment

FIG. 1is a block diagram illustrating a configuration of a position management system relevant to the first exemplary embodiment of the present invention.

A position management system1according to this exemplary embodiment includes a position management device10and three imaging devices20-1to20-3. The imaging devices20-1to20-3are devices which take images; typical examples include color cameras, black-and-white cameras, thermal cameras, and the like. The imaging devices20-1to20-3take images in an image format generally used for image analysis processing such as BMP (Bit MaP) or JPEG (Joint Photographic Experts Group). Each of the imaging devices20-1to20-3takes an image of an object being monitored2from its own direction cyclically, for example at intervals of one second, and transmits data of the taken image to the position management device10. Note that the object being monitored2in this exemplary embodiment is a person, for example.

The position management device10includes calculation units100-1to100-3, comparison units101-1to101-3, an identification unit102, and a storage unit103.

The calculation units100-1to100-3sequentially give identification information for identifying the object being monitored2recorded in the image data that has been received from the respective imaging devices20-1to20-3. The calculation units100-1to100-3sequentially calculate the positional information of the object being monitored2for every imaging time based on the image data received from the respective imaging devices20-1to20-3, and then sequentially transmit the calculated results to the respective comparison units101-1to101-3. The calculation units100-1to100-3also transmit the above-described calculated results to the storage unit103.

Note that the calculation units100-1to100-3and the comparison units101-1to101-3may be combined into one calculation unit and one comparison unit, respectively. In this case, each of the combined calculation unit and comparison unit performs the above-described processing on three sets of image data received from the imaging devices20-1to20-3.

The storage unit103associates identification information for identifying the imaging devices20-1to20-3, identification information for identifying the object being monitored2and an imaging time with the positional information of the object being monitored2received from the calculation units100-1to100-3, and stores these associated items as a calculated position result104.

FIG. 4represents an example composition of the calculated position result104. The table illustrated inFIG. 4represents that an imaging device ID, an object ID, a time, and coordinates of the object imaged by such imaging device at each time are associated with one another. The imaging device ID is identification information for identifying the imaging devices20-1to20-3, and the imaging device IDs corresponding to the imaging devices20-1to20-3are 001 to 003, respectively.

The object ID is identification information given by the calculation units100-1to100-3to the object being monitored2, and the object ID for the object being monitored2is 01a. Note that an object ID, “01b”, is given by the calculation units100-1to100-3to another object being monitored which is not illustrated inFIG. 1and is different from the object being monitored2.

The current time is t. The positional information of the object being monitored2, calculated by the calculation units100-1to100-3based on image data for the object being monitored2imaged by the imaging devices20-1to20-3at a time t, is coordinates A. In this exemplary embodiment, an imaging area taken by the imaging devices20-1to20-3is regarded as a virtual space, and the positional information of the object being monitored2is represented by two-dimensional coordinates on the virtual space, namely an x coordinate on the horizontal axis and a y coordinate on the vertical axis. The coordinates A calculated from the image data taken by the imaging devices20-1to20-3are (x1, y1), (x1, y1), and (x1′, y1′), respectively. The coordinates A (x1′, y1′) calculated from the image data taken by the imaging device20-3is different from the coordinates A (x1, y1) calculated from the image data taken by the imaging devices20-1and20-2. This is because the imaging device20-3produced an erroneous output of image data due to some trouble such as a disturbed image at the time t.

As illustrated inFIG. 4, the calculated position result104contains the above-described data recorded at cyclical imaging times. The positional information of the object being monitored2, calculated by the calculation units100-1to100-3based on image data taken by the imaging devices20-1to20-3at a time (t−1) which is one cycle prior to the time t, for example one second prior to the time t, is coordinates B. Similarly, the positional information of the object being monitored2, calculated by the calculation units100-1to100-3based on image data taken by the imaging devices20-1to20-3at a time (t−2) which is two cycles prior to the time t, for example two seconds prior to the time t, is coordinates C.

The comparison units101-1to101-3sequentially receive the positional information of the object being monitored2in relation to the respective imaging devices20-1to20-3as of the time t, and then determine whether or not the received positional information is valid. Details of validity determination operations performed by the comparison units101-1to103-3will be described below.

As long as any one of the comparison units101-1to101-3determines that the positional information on the received object being monitored2as of the time t is valid, it transmits the information to the identification unit102. For example, suppose that the comparison unit101-3has determined that the positional information calculated from the image data taken by the imaging device20-3is invalid. In this case, the identification unit102will only receive, from the comparison units101-1to101-2, the positional information calculated from the image data taken by the imaging devices20-1to20-2.

The identification unit102identifies the position of the object being monitored2as of the time t based on sets of the positional information received from the comparison units101-1to101-3. The identification unit102identifies the position by, for example, calculating the average of a plurality of positional information values. Another method for the identification may be determining a value based on a majority rule assuming that positional information values within a certain range of error are regarded as the same value.

The identification unit102transmits an identified result with respect to the position of the object being monitored2to the storage unit103. The storage unit103associates identification information for identifying the object being monitored2and an imaging time with the identified result of the position of the object being monitored2received from the identification unit102, and stores these associated items as an identified position result105.

FIG. 5represents an example composition of the identified position result105. The table illustrated inFIG. 5represents that an object ID, a time, and object coordinates identified by the identification unit102as of each time are associated with one another. The coordinates A, B, and C with respect to the object being monitored2whose object ID is 01a, identified for the times t, (t−1), and (t−2) are (x4, y4), (x5, y5), and (x6, y6), respectively.

Now details are described about validity determination operations performed by the comparison unit101-i(i=1, 2, 3) on positional information of the object being monitored2.

The comparison unit101-ireceives from the calculation unit100-ithe positional information of the object being monitored2that has been calculated from the image data taken by the imaging device20-iat a time t. In this case, the comparison unit101-iextracts the positional information of the object being monitored2relevant to the imaging device20-ias of times (t−1) and (t−2) from the calculated position result104and from the identified position result105. The comparison unit101-icalculates the absolute value of the difference between the value as of the time t and the value as of each of the times (t−1) and (t−2) with respect to the positional information of the object being monitored2relevant to the imaging device20-i.

The comparison unit101-icompares the above-described absolute value with a predetermined reference value. In this exemplary embodiment, the administrator of the position management system1has set reference values in the comparison unit101-ias a reference value cc for the x coordinate and a reference value β for the y coordinate. The reference values α and β are calculated by the administrator of the position management system1from the moving speed of a person monitored by the position management system1based on a distance by which a person possibly moves in a time equivalent to one cycle. In this exemplary embodiment, the comparison unit101-icalculates the absolute value of the difference between the value as of the time t and the value as of each of the times (t−1) and (t−2) with respect the positional information of the object being monitored2, and makes a comparison with the reference values α and β. Accordingly, the reference values α and β represent a distance by which a person possibly moves in a time equivalent to two cycles, and are already set by the administrator of the position management system1. For example, if one cycle time is one second, the reference values α and β would be about a few meters.

Note that it is possible to make the criteria stricter or more relaxed by changing the reference values α and β. Alternatively, instead of using reference values specified for x and y coordinates, the comparison unit101-imay use a single reference value which represents a moving distance of the object being monitored2calculated from the values representing the coordinates of the object being monitored2before and after it moves.

During comparison of the above-described absolute value of the difference with the reference values α and β, the comparison unit101-idetermines that the coordinates of the object being monitored2have no problem for the moment if the absolute value of the difference for the x coordinate is less than cc and the absolute value of the difference for the y coordinate is less than β.

FIG. 6represents an example result list of positional information validity determination performed by the comparison unit101-iwith respect to the imaging device20-i. The table illustrated inFIG. 6represents that a source of extracted data, a time, extracted data corresponding to the time and each imaging device, a result of calculation in the comparison unit101, and a determination result are associated with one another. In the determination result list106illustrated inFIG. 6, the format of data extracted from an imaging device and a calculated position result104is {imaging device ID, object ID, calculated object coordinates, imaging time}. Thus, for example, the data {001,01a,(x1,y1),t} represents that “the coordinates of the object being monitored2whose object ID is 01a as of a time t calculated from the image data taken by an imaging device20-1whose imaging device ID is 001 are (x1, y1).”

As illustrated inFIG. 6, the moving distance of the x coordinate |x1−x2| and the moving distance of the y coordinate |y1−y2| between times (t−1) and t with respect to the object being monitored2, calculated from the images taken by the imaging device20-1are less than reference values α and β, respectively. Thus, the comparison unit101-1determines that the coordinates of the object being monitored2as of the time t calculated from the image taken by the imaging device20-1are OK. Likewise, the comparison unit101-2determines that the coordinates of the object being monitored2as of the time t calculated from the image taken by the imaging device20-2are also OK.

The moving distance of the x coordinate |x1′−x2′| and the moving distance of the y coordinate |y1′−y2′| between the times (t−1) and t with respect to the object being monitored2, calculated from the images taken by the imaging device20-3are greater than the reference values α and β, respectively. Thus, the comparison unit101-3determines that the coordinates of the object being monitored2as of the time t calculated from the image taken by the imaging device20-3are inappropriate.

Likewise, on the data extracted from an identified position result105, the comparison unit101-icalculates absolute values of differences from the x and y coordinates as of the time t extracted from the imaging device20-i, and then makes comparisons with reference values α and β.

InFIG. 6, the format of data extracted from an identified position result105is {object ID, calculated object coordinates, imaging time}. Thus, for example, the data {01a,(x5,y5),(t−1)} represents that “the coordinates of an object being monitored2whose object ID is 01a as of a time (t−1) identified by the identification unit102are (x5, y5).”

As illustrated inFIG. 6, the moving distance of the x coordinate |x1−x5| and the moving distance of the y coordinate |y1−y5| between times (t−1) and t with respect to the object being monitored2, calculated from the images taken by the imaging device20-1are less than reference values α and β, respectively. Thus, the comparison unit101-1determines that the coordinates of the object being monitored2as of the time t calculated from the image taken by the imaging device20-1are OK. Likewise, the comparison unit101-2determines that the coordinates of the object being monitored2as of the time t calculated from the image taken by the imaging device20-2are also OK.

The moving distance of the x coordinate |x1′−x5| and the moving distance of the y coordinate |y1′−y5| between the times (t−1) and t with respect to the object being monitored2, calculated from the images taken by the imaging device20-3are greater than the reference values α and β, respectively. Thus, the comparison unit101-3determines that the coordinates of the object being monitored2as of the time t calculated from the image taken by the imaging device20-3are inappropriate.

The comparison unit101-i, based on the above-described individual determination results, determines whether the positional information of the object being monitored2with respect to the imaging device20-ias of the time t is finally valid or not following a predetermined determination flow. The determination flow will be described below where an operation flow according to this exemplary embodiment is explained.

Operations according to this exemplary embodiment will now be described in detail with reference to flowcharts inFIGS. 2 and 3.

The position management system1sets a loop operation between S101and S109, where i=1 to 3 (S101). The imaging device20-itransmits an image of the object being monitored2taken at a time t to the calculation unit100-i(S102). The calculation unit100-igives identification information for identifying the object being monitored2, and calculates the positional information of the object2from the image taken by the imaging device20-i. The calculation unit100-itransmits the calculated result to the comparison unit101-iand the storage unit103(S103). The storage unit103associates identification information for identifying the imaging device20-i, identification information for identifying the object being monitored2and an imaging time with the positional information of the object being monitored2as of the time t received from the calculation unit100-i, and stores these associated items as a calculated position result104(S104). The comparison unit101-idetermines whether the positional information as of the time t received from the calculation unit100-iis valid or not (S105).

Explanation is now provided below following the flowchart inFIG. 3.

The comparison unit101-iextracts the positional information of the object being monitored2as of a time (t−1) from the calculated position result104in the storage unit103. The comparison unit101-icalculates the absolute value of the difference between the extracted positional information and the positional information as of the time t received from the calculation unit100-i, and makes a comparison with a reference value (S201). If the absolute value of the difference is equal to or greater than the reference value (Yes in S202), the processing branches to S203. If the absolute value of the difference is less than the reference value (No in S202), the processing branches to S205. The comparison unit101-iextracts the positional information of the object being monitored2as of a time (t−2) from the calculated position result104in the storage unit103. The comparison unit101-icalculates the absolute value of the difference between the extracted positional information and the positional information as of the time t received from the calculation unit100-i, and makes a comparison with a reference value (S203). If the absolute value of the difference is equal to or greater than the reference value (Yes in S204), the processing branches to S210. If the absolute value of the difference is less than the reference value (No in S204), the processing branches to S205.

The comparison unit101-iextracts the positional information of the object being monitored2as of a time (t−1) identified by the identification unit102from the identified position result105in the storage unit103. The comparison unit101-icalculates the absolute value of the difference between the extracted positional information and the positional information as of the time t received from the calculation unit100-i, and makes a comparison with a reference value (S205). If the absolute value of the difference is equal to or greater than the reference value (Yes in S206), the processing branches to S207. If the absolute value of the difference is less than the reference value (No in S206), the processing branches to S209. The comparison unit101-iextracts the positional information of the object being monitored2as of a time (t−2) identified by the identification unit102from the identified position result105in the storage unit103. The comparison unit101-icalculates the absolute value of the difference between the extracted positional information and the positional information as of the time t received from the calculation unit100-i, and makes a comparison with a reference value (S207).

If the absolute value of the difference is equal to or greater than the reference value (Yes in S208), the processing branches to S210. If the absolute value of the difference is less than the reference value (No in S208), the processing branches to S209. The comparison unit101-idetermines that the positional information as of the time t received from the calculation unit100-iis valid (S209), and then the processing returns to S105. The comparison unit101-idetermines that the positional information as of the time t received from the calculation unit100-iis invalid (S210), and then the processing returns to S105.

Explanation is now provided below following the flowchart back inFIG. 2.

If the positional information is valid (Yes in S106), the processing branches to S107. If the positional information is invalid (No in S106), the processing branches to S108. The comparison unit101-itransmits the positional information as of the time t to the identification unit102(S107). The comparison unit101-idiscards the positional information as of the time t (S108). After completion of every loop operation from S101for i=1 to 3, the processing goes to S110(S109).

Based on the positional information as of the time t received from the comparison units101-1to101-3, the identification unit102identifies the position of the object being monitored2, and then transmits the identified result to the storage unit103(S110). The storage unit103associates identification information for identifying the object being monitored2and an imaging time with the identified result received from the identification unit102, and stores these associated items as an identified position result105(S111), and then the whole processing is finished.

This exemplary embodiment has the effect of calculating, with high precision, the positional information on an object being monitored from images taken by a plurality of imaging devices. This is because the comparison unit101-imakes a comparison with the difference between the positional information of the object being monitored calculated from images taken by individual imaging devices and the positional information in the calculated position result104as well as in the identified position result105, and if the comparison result does not meet predetermined criteria, the comparison unit discards the positional information calculated from the image taken by the applicable imaging device.

If any defect is contained in an image taken by any of the plurality of imaging devices, there will be a large error of positional information of the object being monitored calculated from that image. Thus, if the identification unit102uses the positional information with such large error, the identified position result about the object being monitored will be significantly less accurate.

For example, if the object being monitored is a person walking, it is improbable that he/she moves at high speed; his/her moving distance per unit time has an upper limit. Suppose that the upper limit is exceeded by a moving distance of an object being monitored that is calculated from the positional information of the object being monitored calculated from the image taken by a certain imaging device. In this case, it is highly probable that the image taken by the imaging device contains a defect, causing the calculation unit to calculate the positional information erroneously.

In this exemplary embodiment, the storage unit103stores positional information on an object being monitored as of every cyclic time, calculated from images taken by a plurality of imaging devices. In addition, the comparison unit101-idiscards any defective positional information based on a difference between the positional information as of the current time and the positional information as of a time one or two cycles prior to the current time, as well as on an upper limit of a moving distance described above. This enables the identification unit102to identify the position of an object being monitored with high precision.

In addition, in this exemplary embodiment, the comparison unit101-ireferences not only the calculated position result104but also the identified position result105for performing the above-described comparison. In some cases, the calculated position result104may possibly contain less precise positional information. Thus, additional reference to the identified position result105by the comparison unit101enables to further improve the accuracy of the identified position result identified by the identification unit102.

Second Exemplary Embodiment

A second exemplary embodiment of the present invention will now be explained in detail with reference to the drawings.

FIG. 7is a block diagram illustrating a configuration of a position management system relevant to the second exemplary embodiment of the present invention.

A position management system1includes a position management device10and an imaging device20-1. The position management device10includes a calculation unit100-1, a comparison unit101-1, and a storage unit103. The calculation unit100-1gives identification information for identifying an object being monitored to the object being monitored2whose images were cyclically taken by the imaging device20-1, and calculates the positional information of the object being monitored2from the taken images of the object being monitored2. The storage unit103associates identification information for identifying the object being monitored2and an imaging time with the above-described positional information, and stores these associated items as a calculated position result104.

With respect to the object being monitored2, the comparison unit101-1compares an absolute value of a difference between the positional information value as of the current time and the positional information value as of each of imaging times one cycle and two cycles prior to the current time, as stored in the storage unit103, with a predetermined reference value. The comparison unit101-1then outputs the positional information as of the current time if the absolute value of the difference for at least one of the above-described imaging times is less than the reference value.

On the data extracted from the calculated position result104, the comparison unit101-1calculates the absolute values of differences from the x and y coordinates as of the time t extracted from the imaging device20-1, and then makes comparisons with reference values α and β. Individual validity determination operations performed by the comparison unit101-1with respect to the positional information of the object being monitored2are the same as in the first exemplary embodiment.

Operations according to this exemplary embodiment will now be described in detail with reference to the flowchart inFIG. 8.

The imaging device20-1transmits an image of the object being monitored2taken at a time t to the calculation unit100-1(S301). The calculation unit100-1gives identification information for identifying the object being monitored2, calculates the positional information of the object2from the image taken by the imaging device20-1, and then transmits the calculated result to the comparison unit101-1and the storage unit103(S302). The storage unit103associates identification information for identifying the imaging device20-1, identification information for identifying the object being monitored2and an imaging time with the positional information of the object being monitored2as of the time t received from the calculation unit100-1, and stores these associated items as a calculated position result104(S303). The comparison unit101-1extracts the positional information of the object being monitored2as of a time (t−1) from the calculated position result104in the storage unit103. The comparison unit101-1calculates the absolute value of the difference between the extracted positional information and the positional information as of the time t received from the calculation unit100-1, and makes a comparison with a reference value (S304).

If the absolute value of the difference is equal to or greater than the reference value (Yes in S305), the processing branches to S306. If the absolute value of the difference is less than the reference value (No in S305), the processing branches to S308. The comparison unit101-1extracts the positional information of the object being monitored2as of a time (t−2) from the calculated position result104in the storage unit103. The comparison unit101-1calculates the absolute value of the difference between the extracted positional information and the positional information as of the time t received from the calculation unit100-1, and makes a comparison with a reference value (S306). If the absolute value of the difference is equal to or greater than the reference value (Yes in S307), the comparison unit101-1discards the positional information as of the time t (S309), and then the whole processing is finished. If the absolute value of the difference is less than the reference value (No in S307), the comparison unit101-1outputs the positional information as of the time t (S308), and then the whole processing is finished.

This exemplary embodiment has the effect of calculating, with high precision, the positional information on an object being monitored from images taken by an imaging device. This is because the comparison unit101-1makes a comparison with the difference between the positional information of the object being monitored calculated from an image taken by the imaging device and the positional information in the calculated position result104, and if the comparison result does not meet predetermined criteria, the comparison unit discards the positional information calculated from the image taken by the imaging device.

The positional information which is output by the comparison unit101-1will be used, for example, for identifying the positional information of the object being monitored, as in the first exemplary embodiment. Thus, the comparison unit101-1enables to avoid decreasing accuracy in identification of a position by discarding any positional information having a large error.

<Example of Hardware Configuration>

In the above exemplary embodiments, each unit illustrated inFIGS. 1 and 7can be regarded as a function (processing) unit (software module) of a software program. However, the individual unit separations illustrated in these figures represent a configuration for explanatory convenience only, and a variety of configurations can be envisaged for implementation. One example of a hardware environment in such cases is explained below with reference toFIG. 9.

FIG. 9illustrates, by way of example, a configuration of an information processing apparatus900(computer) which can implement a position management device relevant to an exemplary embodiment of the present invention. In other words,FIG. 9illustrates a configuration of a computer (information processing apparatus) capable of implementing the information processing devices illustrated inFIGS. 1 and 7, representing a hardware environment where the individual functions in the above-described exemplary embodiments can be implemented.

The information processing apparatus900illustrated inFIG. 9includes the following as components:CPU901(Central_Processing_Unit);ROM902(Read_Only_Memory);RAM903(Random_Access_Memory);Hard disk904(storage device);Communication interface to an external device905(Interface: hereinafter called “I/F”);Reader/writer908capable of reading and writing data stored in a storage medium907such as CD-ROM (Compact_Disc_Read_Only—Memory); andInput/output interface909.

The information processing apparatus900is a general computer where these components are connected via a bus906(communication line).

The present invention explained with the above-described exemplary embodiments as examples is accomplished by providing the information processing apparatus900illustrated inFIG. 9with a computer program which is capable of implementing the functions illustrated in the block diagrams (FIGS. 1 and 7) or the flowcharts (FIGS. 2, 3, and 8) referenced in the explanation of these embodiments, and then by reading the computer program into the CPU901in such hardware, interpreting it, and executing it. The computer program provided to the apparatus can be stored in a volatile readable and writable storage memory (RAM903) or in a nonvolatile storage device such as the hard disk904.

In addition, in the case described above, general procedures can now be used to provide the computer program to such hardware. These procedures include, for example, installing the computer program into the apparatus via any of various storage media907such as CD-ROM, or downloading it from an external source via communication lines such as the Internet. In these cases, the present invention can be seen as being composed of codes forming such computer program or being composed of the storage medium907storing the codes.

The present invention has been explained above with the above-described embodiments as exemplary examples. However, the present invention is not limited to the above-described exemplary embodiments. In other words, various aspects of the present invention that could be understood by those skilled in the art may be applied within the scope of the present invention.

This application claims priority based on Japanese Patent Application No. 2012-148404 filed on Jul. 2, 2012, the entire disclosure of which is herein incorporated.

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