Calibrating a dimensioner using ratios of measurable parameters of optically-perceptible geometric elements

FIELD OF THE INVENTION

0001The present invention relates to dimensioners that determine the volume of an object and, more particularly, to systems and methods for calibrating dimensioners.

BACKGROUND

0002In packaging and shipping industries, volume and weight are calculated for determining shipping costs. Also, the volume of packages can be used for determining strategies for loading the packages onto transport vehicles and for other applications. For instance, the volume of a rectangular box can be calculated by measuring the length, width, and height of the box. Measurements done by hand can be time-consuming, especially if several packages are to be measured.

0003Volume dimensioners, or simply "dimensioners," are electronic devices that provide a faster way to calculate the volume of objects. A dimensioner is configured to obtain dimensions of an object as well as distance calculations from the dimensioner itself to various parts of the object. From this information, the dimensioner is able to calculate the volume of a package. When used with a conveyor system, some dimensioners are capable of calculating the volume of dozens of packages per minute.

0004As with many types of measurement devices, the accuracy of a dimensioner may be compromised by any number of factors. For example, if an object collides with a dimensioner or if a portable dimensioner is dropped on a hard surface, the optical components of the dimensioner can be damaged, thereby degrading the accuracy of the dimensioner. Thus, dimensioners may require occasional calibration or tuning. Therefore, a need exists for providing systems and methods for calibrating dimensioners.

0005<patcit id="pcit0001" dnum="US2002105639A1"><text>US 2002/105639 A1</text></patcit> describes a calibration artifact for a machine vision measurement system, including a number of concentric rings on a surface of a substrate.

0006<patcit id="pcit0002" dnum="US2016065912A1"><text>US 2016/065912 A1</text></patcit> describes triggering image acquisition of moving objects using motion data from a motion drive.

0007<patcit id="pcit0003" dnum="US2014049635A1"><text>US 2014/049635 A1</text></patcit> relates to volume-dimensioning-system calibration systems and methods useful in promoting compliance with governmental or industry standard calibration guidelines.

SUMMARY

0008Aspects of the present invention are defined by appended independent claims 1 and 6. Specific embodiments are defined in the dependent claims.

0009The foregoing illustrative summary, as well as other exemplary objectives and/or advantages of the invention, and the manner in which the same are accomplished, are further explained within the following detailed description and its accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

0010<ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">FIG. 1</figref> schematically depicts a diagram of a dimensioning station of a conveyor system according to an embodiment of the present invention.</li><li><figref idref="f0002">FIGS. 2A and 2B</figref> schematically depict a diagram of a portable dimensioning device according to an embodiment of the present invention.</li><li><figref idref="f0002">FIG. 3</figref> schematically depicts a diagram of another portable dimension device according to an embodiment of the present invention.</li><li><figref idref="f0003">FIG. 4</figref> depicts a perspective view of an object from the viewpoint of a dimensioner according to an embodiment of the present invention.</li><li><figref idref="f0003">FIG. 5</figref> depicts a wire frame view of the object shown in <figref idref="f0003">FIG. 4</figref> as determined by a dimensioner.</li><li><figref idref="f0004">FIG. 6</figref> depicts a view of a first reference pattern for calibrating a dimensioner, according to an embodiment of the present invention.</li><li><figref idref="f0005">FIG. 7</figref> depicts a view of a second reference pattern for calibrating a dimensioner, according to an embodiment of the present invention.</li><li><figref idref="f0006">FIG. 8</figref> depicts a view of a third reference pattern for calibrating a dimensioner, according to an embodiment of the present invention.</li><li><figref idref="f0007">FIGS. 9A-9C</figref> depict various perspective views of the first reference pattern of <figref idref="f0004">FIG. 6</figref> as obtained by a dimensioner during a calibration process according to an embodiment of the present invention.</li><li><figref idref="f0008">FIG. 10</figref> schematically depicts a block diagram showing circuitry of a dimensioner according to an embodiment of the present invention.</li><li><figref idref="f0009">FIG. 11</figref> schematically depicts a flow diagram of a method for calibrating a dimensioner according to an embodiment of the present invention.</li></ul>

DETAILED DESCRIPTION

0011The present invention is directed to systems and methods of calibrating a dimensioner, which is a device used for measuring the volume of an object without actually touching the object. In a system where customers are charged based on the volume of a package to be shipped, it is important that devices for measuring volume are accurate within a certain tolerance.

0012Therefore, the present invention is configured to calibrate dimensioners and furthermore is configured to provide validation that the dimensioner has been properly calibrated. With verifiable calibration and validation, a dimensioner can be certified as complying with certain accuracy standards, such as those that may be established by the National Institute of Standards and Technology (NIST) or other agencies. Without properly enforced standards, an unscrupulous vendor could cheat customers by fraudulently manipulating a dimensioner to measure volume so that pricing will be slightly higher for customers.

0013One solution to calibrating a dimensioner is to provide a reference object having predetermined physical characteristics, such as fixed lengths and widths. However, in some situations, an unscrupulous user may reproduce the reference object such that the reproduction is slightly smaller (e.g., by about 5%) than the authentic reference object. Thus, if the dimensioner is calibrated using the fraudulent reference object, the dimensioner would output dimensions that are slightly bigger (e.g., by about 5%). Therefore, another solution for calibrating dimensioners may be needed to prevent such a fraudulent practice.

0014According to some embodiments of the present invention, a predetermined reference pattern of two-dimensional optically-perceptible geometric elements is used for calibrating a dimensioner. The pattern of optically-perceptible geometric elements may include a plurality of predefined measurable parameters, such as the radius or diameter of a circle, width or height of a square, or other dimensions of other geometric elements. Other measurable parameters may also include the distances between the geometric elements. Thus, not only are the parameters of the geometric elements predefined, but also the ratios of one of these parameters to another is predefined as well. Therefore, the dimensioner can be calibrated reliably using ratios regardless of whether a reference pattern has been reduced or enlarged in size. Specifically, the ratios will be the same regardless of the degree of magnification of the reference pattern. The dimensioner can capture images of the optically-perceptible geometric elements of the reference pattern from various distances and angles.

0015For example, the optically-perceptible geometric elements may be circles having a predetermined diameter, and the circles may be separated from each other by a predetermined distance. One ratio may be based on a diameter value with respect to a separation distance. Also, distance measurements from the dimensioner to various points on the reference pattern may be used to determine values that may be used in ratio calculations.

0016From the captured images of the optically-perceptible geometric elements, a calibration process utilizing the ratios of certain parameters of the elements can be performed. Once the ratios are determined, these ratios can be compared with predefined ratios of the reference pattern. From this comparison, the dimensioner can be calibrated, either by itself or by a certifying agency. For example, self-calibration can be performed by making adjustments in the processing components of the dimensioner itself.

0017Multiple reference patterns having different sizes and shapes of optically-perceptible geometric elements can be used to calibrate the dimensioners. By utilizing ratios of the reference pattern instead of actual size measurements, fraud can be prevented since any reproduction of the reference pattern will maintain the same ratios regardless of any changes in the size of the reproduction with respect to the genuine reference pattern.

0018<figref idref="f0001">FIG. 1</figref> shows an embodiment of a dimensioning station 10, which is positioned at a fixed location along a conveyor system 12. In some embodiments, the conveyor system 12 may contain a conveyor belt 14, which not only provides a level surface on which objects 16 can travel, but can also provide an optical reference background for a dimensioner. The objects 16, such as various types of packages or boxes, are conveyed along the conveyor system 12. The dimensioning station 10 further includes a support structure 18 that supports a fixed dimensioner 20 positioned above a section of the conveyor system 12.

0019The support structure 18 and fixed dimensioner 20 can be installed as shown or in any number of suitable configurations as would be understood by one of ordinary skill in the art. For example, in an alternative embodiment, the dimensioner can be mounted above a table whereby a user manually places one package at a time onto the surface of the table for dimensioning measurements.

0020The fixed dimensioner 20 includes imaging and sensing components for capturing images of the objects 16 and for determining distances from the fixed dimensioner 20 to the objects 16 as they pass below. Since the fixed dimensioner 20 is in a fixed position above the objects 16, the fixed dimensioner 20 can be tuned according to a known distance from the dimensioner 20 to a "background" surface (e.g., the conveyor belt 14). By imaging two or three sides of the objects 16, the fixed dimensioner 20 can determine volume. In some embodiments, the fixed dimensioner 20 may be capable of determining volume of an object 16 by viewing only its top surface. The fixed dimensioner 20 may also be configured to calculate the volume of each of two or more boxes 16 even when they are touching each other.

0021<figref idref="f0002">FIG. 2A</figref> is a front view of an embodiment of a portable dimensioning device 24 and <figref idref="f0002">FIG. 2B</figref> is a back view of the portable dimensioning device 24. The portable dimensioning device 24 includes at least a housing 26, a display screen 28, user input devices 30, an image sensor 32, and a distance sensing device 34. In some embodiments, the portable dimensioning device 24 may be a mobile phone, a smart phone, a portable computing device, or other similar device, or alternatively may be incorporated into or attached to a mobile phone, smart phone, or portable computing device.

0022The image sensor 32 may include a camera, video camera, infrared camera, charge-coupled device (CCD), or other type of sensing device for capturing images. The distance sensing device 34 may include infrared sensors, laser diodes, sound wave reflection devices, stereo cameras, or other sensing devices for measuring distances. In some embodiments, the portable dimensioning device 24 may include multiple image sensors 32 and/or multiple distance sensing devices 34.

0023In operation, the image sensor 32 is configured to capture one or more images of an object for which dimensions are to be determined. The one or more images may be displayed on the display screen 28. An option such as "Calculate Volume" or other similar command may be available to the user and may be shown on the display screen 28. If the user wishes that the volume is determined for the displayed object, the user may press a button or enter a voice command (e.g., using one or more of user input devices 30), touch an area of the display screen 28, or enter an input using another suitable input device of the portable dimensioning device 24.

0024When instructed by the user to calculate the volume of the object, the portable dimensioning device 24 processes the image information and distance information. Using dimensioning algorithms, the portable dimensioning device 24 calculates the volume of the object. The volume can be displayed on the display screen 28 and may be in any suitable unit of measure, such as mm³, cm³, inch³, etc. The display screen 28 may also be configured to display particular dimensions, such as length, width, and height.

0025<figref idref="f0002">FIG. 3</figref> is a perspective view of another embodiment of a portable dimensioning device 36. In this embodiment, the portable dimensioning device 36 may be incorporated in a barcode reader. The portable dimensioning device 36 of <figref idref="f0002">FIG. 3</figref> may include one or more image sensors (e.g., sensors similar to the image sensor 32 shown in <figref idref="f0002">FIG. 2B</figref>) and one or more distance sensing devices (e.g., devices similar to the distance sensing device 34 also shown in <figref idref="f0002">FIG. 2B</figref>).

0026<figref idref="f0003">FIG. 4</figref> is a perspective view of an object 40 to be optically sensed by a dimensioner (e.g., portable dimensioning device 24 or 36). In this example, the object 40 is observed from a perspective such that three of its six sides are in view. From this same perspective, seven of the eight corners of the object 40 are in view and nine of its twelve edges are in view.

0027From the optically sensed view of <figref idref="f0003">FIG. 4</figref>, the dimensioner is configured to construct a wire frame view 50 of the object 40, as shown in <figref idref="f0003">FIG. 5</figref>. The wire frame view 50 outlines the physical features of the object 40 and shows the corners and edges that are directly in view from the perspective of the dimensioner. In addition, the dimensioner is able perform vanishing point calculations or other suitable algorithms to fill in the eighth corner and the three obstructed edges to complete the construction of the wire frame view 50.

0028With the wire frame view 50 completed and distance measurements calculated, the dimensioner is able to calculate length, width, and height values. From these values, the dimensioner can determine the volume of the object 40.

0029<figref idref="f0004">FIG. 6</figref> illustrates an embodiment of a reference pattern 60 having any number of optically-perceptible geometric elements of at least two different sizes. As shown in <figref idref="f0004">FIG. 6</figref>, the reference pattern 60 includes a diagonal grid of small circles 62, medium-sized circles 64, and large circles 66. It should be noted that the reference pattern 60 may include elements having any number of different sizes. Although <figref idref="f0004">FIG. 6</figref> illustrates a pattern of circles, it should be noted that according to other embodiments, the reference pattern 60 may include a pattern of other types of geometric elements, such as squares, hexagons, triangles, etc. The reference pattern 60 of <figref idref="f0004">FIG. 6</figref> may be applied to (e.g., printed on, painted on, affixed to) a reference object in any suitable manner, wherein the reference object may be any suitable rigid material having a surface that substantially forms a plane.

0030In particular, the reference pattern 60 of <figref idref="f0004">FIG. 6</figref> includes small circles 62 each having a diameter of value "a" and separated from each other by distance "b". Medium-sized circles 64 each have a diameter of value "c" and are separated from each other by distance "d". Also, large circles 66 each have a diameter of value "e" and are separated from each other by distance "f". Other measurable parameters, such as distances between elements of different sizes, may also be predefined.

0031According to the illustrated example, the predefined ratio of "a" to "b" is about 4:7; the predefined ratio of "c" to "d" is about 7:15; and the predefined ratio of "e" to "f" is about 5:17. In other embodiments, the circles 62, 64, 66 may have any predetermined diameters and may be separated by any predetermined distance. Other dimensions may also be predefined in the pattern 60. For example, dimensions of distances from a geometric element having a first size to a geometric element having a different size may be predetermined and may be utilized in the calibration process.

0032Also, any ratios based on any arbitrary measurable parameters of the pattern 60 can be established beforehand. Then, these pre-established ratios can then be compared with ratios calculated by the dimensioner based on the measured parameters. The dimensioner can then be calibrated based on the comparison between the actual pre-established ratios and the calculated ratios, which is independent of any magnification of the reference pattern.

0033Since the ratios are not based on any alteration of the size of the reference pattern, the calibration process can be certified as authentic. Therefore, dimensioners having the capability of calculating the relevant ratios according to the teachings herein can perform a certified self-calibration process. In some cases, the dimensioner may be calibrated by a certified agency using the ratio-based calibration processes as described in the present disclosure.

0034One reason that different sizes of geometric elements (e.g., circles 62, 64, 66) are included in the reference pattern 60 is that a dimensioner may be able to capture images of the smaller elements when taken at a closer range from the pattern 60, whereby the larger elements may be more easily viewed when images are captured from a greater distance. Thus, the reference pattern 60 can be used from many different distances.

0035The elements of the reference pattern 60 of <figref idref="f0004">FIG. 6</figref> may include circles, as illustrated, or may include other suitable geometric shapes, such as squares, hexagons, etc. <figref idref="f0005">FIG. 7</figref> is a view of an embodiment of a reference pattern 70 having square geometric elements instead of circles. The reference pattern 70 may be applied to a reference object (not shown) for support. The reference object may have a surface that substantially forms a plane and that is configured to maintain its size and shape. As shown in <figref idref="f0005">FIG. 7</figref>, the reference pattern 70 includes a diagonal grid of any number of optically-perceptible geometric elements (i.e., squares).

0036In particular, the reference pattern 70 of <figref idref="f0005">FIG. 7</figref> includes small squares 72 each having equal sides of length "g" and separated from each other by distance "h". Medium-sized squares 74 each have equal sides of length "i" and are separated from each other by distance "j". Also, large squares 76 each have equal sides of length "k" and are separated from each other by distance "l". Other measurable parameters, such as distances between elements of different sizes or distances measured in a vertical or horizontal manner, may also be predefined.

0037According to the illustrated example, the ratio of "g" to "h" is about 8:11; the ratio of "i" to "j" is about 7:12; and the ratio of "k" to "l" is about 1:3. In other embodiments, the squares 72, 74, 76 may have any predetermined dimensions and may be separated by any predetermined distances. Other dimensions may also be predefined in the pattern 60. For example, dimensions of distances from one geometric element to another having a different size may be predetermined and may be calculated in the calibration process.

0038Also, the geometric elements of the reference patterns 60 and 70 of <figref idref="f0004">FIGS. 6</figref> and <figref idref="f0005">7</figref>, respectively, are shown as being arranged in a diagonal grid. In other embodiments, the elements may instead be arranged in a rectangular grid, a hexagonal grid, or another suitable arrangement pattern.

0039<figref idref="f0006">FIG. 8</figref> is a view of another embodiment of a reference pattern 80, which may also be applied to a reference object. In some embodiments, the reference pattern 80 may be applied to an opposite surface of the reference object on which reference pattern 60 or 70 is applied. As shown in <figref idref="f0006">FIG. 8</figref>, the reference pattern 80 includes a diagonal grid of small circles 62, medium-sized circles 64, and large circles 66, like those of the embodiment of <figref idref="f0004">FIG. 6</figref>. In addition to the features of <figref idref="f0004">FIG. 6</figref>, the reference pattern 80 of <figref idref="f0006">FIG. 8</figref> may further include a very large circle 82, which can be used to verify size.

0040For instance, during operation, an object having known dimensions, such as currency 84 or other standard-sized manufactured object, can be placed on the very large circle 82. Alternatively, the manufactured object can be placed on a boundary of one or more of the geometrical shapes, between geometrical shapes, or elsewhere on the reference pattern 80. When images are captured, the dimensioner may be configured to determine the actual sizes of the optically-perceptible geometric elements (e.g., circles 62, 64, 66, 82) based on a comparison with the known size of the currency 84 or other object. Also, the dimensioner may further calculate ratio information as mentioned above. From the actual size information and ratio information, the dimensioner can be calibrated effectively.

0041According to some embodiments, the reference pattern 80 may include a pattern of other types of geometric elements, such as squares, hexagons, etc. Similar to the embodiments of <figref idref="f0004">FIGS. 6</figref> and <figref idref="f0005">7</figref>, the reference pattern 80 may also be applied to a reference object in any suitable manner, wherein the reference object may be any suitable rigid material having a surface that forms a plane.

0042In some embodiments, a calibration system may include two or more reference patterns with optically-perceptible geometric elements of different sizes and shapes. Using multiple reference patterns in a calibration system allows a dimensioner to be calibrated based on a greater set of references, which may provide for a more effective calibration.

0043According to one embodiment of a method for using the reference pattern 80, a manufactured object 84 having known dimensions may be placed on or attached to the very large circle 82 or elsewhere on the reference pattern 80. The dimensioner is programmed to recognize the manufactured object 84 and associated the manufactured object 84 with known dimensions. The dimensioner measures the dimensions of both the manufactured object 84 and the very large circle 82. From this information, the dimensioner can verify that the reference pattern 80 is authentic.

0044In some implementations, the method may additionally or alternatively include verification steps that may be performed in front of a notary public for validation. A recognizable symbol, such as a seal of the notary may be recorded in the dimensioner. The notary may provide a manufactured object 84, such as currency, to verify that the manufactured object 84 is authentic.

0045Other embodiments of methods utilizing the reference pattern 80 may include placing or attaching a credit card on the very large circle 82. The dimensioner may store information regarding the known dimensions of the credit card, which are typically produced with precise dimensions. Also, the dimensioner may be configured to detect the three-dimensional aspects of the raised characters on the credit card. In addition to credit cards, other manufactured objects that may be used may include cereal boxes, tape measures, rulers, and other objects. Having a witness, such as a notary public, to verify the authenticity of the calibration may provide further improvements to ensuring that the dimensioner is calibrated legitimately.

0046<figref idref="f0007">FIGS. 9A - 9C</figref> show examples of images of the reference pattern 60 of <figref idref="f0004">FIG. 6</figref> that may be captured by the dimensioner when the dimensioner is placed at various angles and distances with respect to the reference pattern 60. Again, the sizes and shapes of the circles 62, 64, 66 may appear different from their actual sizes and shapes in the two-dimensional view. The dimensioner is configured to determine the ratios not only of the diameters of the circles with respect to the distance between the circles but also the diameters of various circles. From a comparison of the calculated ratios with predetermined ratios, the dimensioner can be calibrated.

0047Because of the focal depth of the sensors of the dimensioners, the images shown in <figref idref="f0007">FIG. 9</figref> may actually include several circles that are out of focus. Therefore, at least one image of the multiple images that are captured can be used in the calculations of diameters and separation distances. The sensors may be configured to determine the circles that are in focus and use these circles in the calculations. With the differences in the sizes of the circles, according to the teachings of the present invention, the sensors can select a specific circle size from the circles that have at least two circles in focus.

0048Although <figref idref="f0007">FIGS. 9A - 9C</figref> show examples of captured images of the reference pattern 60 of <figref idref="f0004">FIG. 6</figref>, it should be noted that different images may be captured of the other reference patterns, such as reference pattern 70 of <figref idref="f0005">FIG. 7</figref> or reference pattern 80 of <figref idref="f0006">FIG. 8</figref>. For example, the actual size of the squares 72, 74, and 76 shown in <figref idref="f0005">FIG. 7</figref> may be different from the captured images of the squares because the dimensioner may capture the images at an angle to make the squares 72, 74, and 76 appear to have different sizes and shapes.

0049Dimensions of the reference patterns 60, 70, and 80 can be calculated by taking into account the relationship of the two-dimensional captured images with actual dimensions. From these calculations, the dimensioner is configured to determine the ratios of the dimensions of the geometric elements with respect to the distance between the geometric elements. From a comparison of the calculated ratios with predetermined ratios, the dimensioner can be calibrated according to the present methods.

0050<figref idref="f0008">FIG. 10</figref> is a block diagram showing an embodiment of circuitry 90 of a dimensioner in accordance with the teachings of the present disclosure. The circuitry 90 may be incorporated in a fixed dimensioner, such as the fixed dimensioner 20 shown in <figref idref="f0001">FIG. 1</figref>, or in a portable dimensioning device, such as the portable dimensioning device 24 or 36 shown in <figref idref="f0002">FIGS. 2 and 3</figref>.

0051As shown in <figref idref="f0008">FIG. 10</figref>, the circuitry 90 includes a processing device 92, sensors 94, a user interface 96, and a memory device 98. A dimensioning module 100 and a calibration module 102 may be stored as software and/or firmware in the memory device 98. In some embodiments, the calibration module 102 may be incorporated in a separate device for providing external calibration to a dimensioner. In alternative embodiments, the dimensioning module 90 and calibration module 92 may be configured at least partially in hardware and contained, for example, in the processing device 92.

0052The processing device 92 may include one or more processors, microprocessors, or other suitable processing elements and may be configured to control and execute the operations of a dimensioner. The processing device 92 may be in communication with the other components 94, 96, 98 via conductors, bus interfaces, or other means.

0053The sensors 94 may include at least one optical sensor (e.g., image sensor 32) for capturing an image of an object, at least one distance sensor (e.g., distance sensing device 34), and/or any suitable combination of one or more sensing devices. The sensors 94 are configured to sense image information and distance information of any object for determining dimensional information according to conventional dimensioner functionality. In addition, the sensors 94 may also sense image and distance information of the geometric elements of the reference patterns 60, 70, 80 shown in <figref idref="f0004 f0005 f0006">FIGS. 6 - 8</figref>. The sensed information obtained by the sensors 94 is forwarded to the processing device 92.

0054The user interface 96 may include any suitable combination of input devices, output devices, and/or input/output devices. For example, the user interface 96 may include a touch screen device (e.g., display screen 28), display device, one or more buttons (e.g., user input devices 30), tactile device, etc.

0055The memory device 98 may comprise any suitable combination of random access memory (RAM), read-only memory (ROM), etc. Also, the memory device 98 may store applications that can be executed by the processing device 92 for controlling the circuitry 90. For example, the dimensioning module 100 may be configured in software or firmware for enabling the dimensioner to perform dimensioning functions as described throughout the present disclosure. In some embodiments, the dimensioning module 100 may be configured as hardware in the processing device 92.

0056The calibration module 102 may be configured to enable the processing device 92 to perform a self-calibration process based on information obtained from the sensors 94 regarding images of the geometric elements of the reference patterns 60, 70, 80. For example, the obtained images may include one or more images, such as those shown in <figref idref="f0007">FIGS. 9A - 9C</figref> or those which may be obtained from other reference patterns (e.g., patterns 70 and 80). The calibration module 102 may further be configured to perform calculations based on measurable parameters of the optically-perceptible geometric elements of the reference patterns and ratios of different measured parameters of the geometric elements of the reference patterns.

0057In some embodiments, the self-calibration functionality of the calibration module 102 may include a process of applying a multiplier (e.g., "multiple by 1.03") to adjust the measurements accordingly. In some embodiments, the calibration module 102 may require a more sophisticated algorithm than a simple multiplication factor to calibrate the dimensioner. In some embodiments, self-calibration may not be allowed if the degree of calibration exceeds an acceptable threshold.

0058<figref idref="f0009">FIG. 11</figref> is a flow diagram showing steps of a method 120 for calibrating a dimensioner. The method 120 includes a step as indicated in block 122 of capturing one or more images of a reference pattern, which may include a plurality of optically-perceptible geometric elements arranged in a predetermined pattern. As indicated in block 124, the method includes measuring a plurality of parameters of the geometric elements in the reference pattern. The measured parameters may include dimensions (e.g., diameter, width, length, height, etc.) of the geometric elements themselves as well as distance values from one geometric element to another. The optically-perceptible geometric elements included in the reference pattern may be circles (e.g., circles 62, 64, 66), squares (e.g., 72, 74, 76), or other geometric shapes. The measurements can be obtained using dimensioner functionality based on captured images and information regarding the distance from the dimensioner to the captured elements. Block 126 indicates a next step of calculating ratios based on the measured parameters of the geometric elements of the reference pattern.

0059According to decision block 128, it is determined whether or not the calculated ratios are within acceptable tolerances. The parameters and ratios may be predefined when the reference pattern is constructed and the ratios may be known by the dimensioner when it uses the reference pattern as a reference for calibration purposes. If an error or discrepancy is minimal (e.g., less than 1% difference between predefined ratios and calculated ratios), then the method proceeds to block 130. It is indicated in block 130 that no changes are needed and the method ends. Also, an output device may display or indicate to the user that the dimensioner is acceptable for continued use and is not in need of calibration.

0060If the calculated ratios are not within an acceptable tolerance (e.g., greater than a 1% discrepancy), the method 120 proceeds to decision block 132, which indicates that it is determined whether self-calibration is permitted. If calibration is needed but self-calibration is not allowed, the dimensioner device should be sent to a certifying agency for re-certification, as indicated in block 134. Instructions and details for sending to the certifying agency may be presented on the display of the dimensioner.

0061If self-calibration is permitted, the method proceeds to block 136, which indicates that the method 120 includes the step of performing a self-calibration function. Self-calibrating may include adjusting a multiplication variable that is used to tune the output values of the dimensioner. Other self-calibration steps may include applying, reconfiguring, or adjusting variables of a measurement algorithm. Therefore, by using ratios between two or more measurable parameters of optically-perceptible elements of a reference pattern, the dimensioner can be calibrated.

0062In the specification and/or figures, typical embodiments of the invention have been disclosed. The present invention is not limited to such exemplary embodiments. The use of the term "and/or" includes any and all combinations of one or more of the associated listed items. The figures are schematic representations and so are not necessarily drawn to scale. Unless otherwise noted, specific terms have been used in a generic and descriptive sense and not for purposes of limitation. The invention is defined in the appended claims.