Method and system for contactless dimensional measurement of articles

Methods and systems for contactless optical measurement of geometrical dimensions of articles are disclosed herein. A system according to the present disclosure may implement an arrangement of one or more measured articles, two imaging setups, a reflecting surface and a reference object. Geometrical dimensions of the one or more measured articles may be derived from dimensions of images formed in the imaging setups.

TECHNICAL FIELD

The inventive concept described herein is generally related to measurement systems and, more specifically, to techniques, schemes and implementations of contactless optical measurement.

BACKGROUND

Unless otherwise indicated herein, approaches described in this section are not prior art to the claims listed below and are not admitted to be prior art by inclusion in this section.

Contactless dimensional measurements of articles are essential when there is a demand for fast and inexpensive estimations of the geometrical dimensions, provided that access to the measured articles is limited or the articles are in motion. For these situations different types of optical systems are typically used. These systems are usually based on the measurement of the projections of the measured articles formed by the optical system with known characteristics. With known or measured distance from the elements of the optical system to the measured articles the geometrical dimensions of the projections are recalculated to the dimensions of the articles. When the distance to the measured articles is not known, however, its contactless estimation would require special equipment, namely different types of range finders including optical ones.

Many everyday applications require fast yet accurate contactless dimensional measurements including, for example, measurements of the parts of a body for placing orders with online clothes retailers or for slimming process assessment. The usage of the range finders or other special equipment in such applications is highly undesirable.

SUMMARY

An objective of the present disclosure is to provide schemes, techniques, methods, apparatuses and systems for measurement of geometrical dimensions of an article without knowledge of a distance to the measured article. Advantageously, implementations of the present disclosure need not obtain a distance to a measured article, and may be implemented in hand-held platforms or solutions for measurement.

In one aspect, a method of measuring geometrical dimensions of articles may include: measuring optical properties of a first imaging setup; measuring optical properties of a second imaging setup; measuring geometrical dimensions of a reference object; arranging one or more measured articles including a first measured article, the second imaging setup, a reflective surface, the first imaging setup, and the reference object in such a way that the first measured article is located in a visual field of the second imaging setup, with a reflection of the first measured article in the reflective surface and a reflection of the reference object in the reflective surface located in a visual field of the first imaging setup; forming an image of the reflection of the first measured article and the reflection of the reference object in the first imaging setup; forming an image of the first measured article in the second imaging setup; measuring geometrical dimensions of the image formed in the first imaging setup; measuring geometrical dimensions of the image formed in the second imaging setup; and calculating geometrical dimensions of the first measured article.

In another aspect, a method of forming and measuring geometrical dimensions of images of reflections may include: setting an imaging device in a front view position in such a way that a reflection of one or more measured articles including a first measured article in a reflective surface and a reflection of a reference object in the reflective surface are located in a visual field of the imaging device; forming images of the reflection of the first measured article and the reflection of the reference object; and measuring geometrical dimensions of the formed images.

In yet another aspect, a method of forming and measuring geometrical dimensions of images of articles may include: setting an imaging device in a rear view position in such a way that a first measured article is located in a visual field of the imaging device; forming an image of the first measured article; and measuring geometrical dimensions of the formed image.

In one aspect, a system for measuring geometrical dimensions of one or more measured articles may include: a front view imaging setup, a rear view imaging setup, a reflective surface, and a reference object. The front view imaging setup, the rear view imaging setup, the reflective surface and the reference object may be arranged in such a way that a first measured article of the one or more measured articles is located in a visual field of the rear view imaging setup, while a reflection of the first measured article in the reflective surface and a reflection of the reference object in the reflective surface are located in a visual field of the front view imaging setup.

Other features and advantages of the present disclosure will become apparent from the following description of various implementations which refer to the accompanying drawings.

DETAILED DESCRIPTION OF PREFERRED IMPLEMENTATIONS

Overview

The present disclosure may be described in terms of various functional components and various processing steps. It should be appreciated that such functional components may be realized by any number of hardware or structural components configured to perform the specified functions. For example, the present disclosure may employ various integrated components comprised of various electrical, mechanical and optical devices.

In addition, the present disclosure may be practiced in any integrated application. Such general applications and other details that will be apparent to those skilled in the art in light of the present disclosure are not described in detail herein. Further, it should be noted that while various components may be suitably coupled or connected to other components within exemplary devices, such connections and couplings may be realized by direct connection between components, or by connection through other components and devices located therebetween.

Referring toFIG. 8, which shows a block diagram of a prior art measurement system800. Prior art measurement system800includes an imaging setup (e.g., a camera of a mobile terminal) which includes a lens810with known characteristics, an image measurement subsystem820, and a distance measurement subsystem830. A method of measurement by prior art measurement system800typically includes the following steps: (1) recognizing an article image taken using the imaging setup; (2) measuring a size of the article image recognized in step (1) with image measurement subsystem820; (3) measuring a distance between the article and the imaging setup with distance measurement subsystem830; and (4) computing a real size of the article using the characteristics of the imaging setup (e.g., focal distance of lens810and the distance at which the image is formed), the size of the article image measured in step (2), and the distance between the object measured in step (3) and the imaging setup.

The operational sequence in prior art measurement system800includes measurement of a distance between the article and the camera which is done by distance measurement subsystem830. There are many practical cases when this distance cannot be measured at all or measurement accuracy does not have the required level, e.g., when the measured article is moving or when there is limited access to the measured article.

In contrast, a primary advantage provided by methods and systems for measurement of geometrical dimensions in accordance with the present disclosure is its operation without the knowledge or direct measurement of the distance to the measured articles. That is, implementations in accordance with the present disclosure enable measurement of geometrical dimensions of articles without the need for means for distance measurement such as distance measurement subsystem830. Such advantage may be achieved by the use of two imaging setups, a reflective surface (e.g., a mirror) and a reference object with known geometrical dimensions. In fact, in various implementations according to the present disclosure, a housing of one of the imaging setups or body of an assembly of two imaging setups may be used as a reference object.

Another feature of a proposed measurement system according to the present disclosure is the use of orientation detectors which are connected to the components of the measurement system. Measurements from the orientation detectors are taken into consideration when calculating the geometrical dimensions of the measured article(s) to compensate for the non-ideal spatial orientation (e.g., pitch and yaw) of the components of the measurement system. This may allow for a hand-held application for measurements.

FIG. 1is a block diagram showing an exemplary optical measurement system100in accordance with at least some implementations of the present disclosure.FIG. 2is a block diagram showing an exemplary imaging setup200of the exemplary measurement system100ofFIG. 1in accordance with at least some implementations of the present disclosure. The following description refers toFIG. 1andFIG. 2.

Exemplary optical measurement system100may include a front view imaging setup110, a rear view imaging setup120, a reflective surface130, and a reference object140. Exemplary imaging setup200illustrates example components of each of front view imaging setup110and rear view imaging setup120. As shown inFIG. 2, front view imaging setup110may include a lens212and an image measurement block214, and rear view imaging setup120may include a lens222and an image measurement block224.

Front view imaging setup110may form an image230through the lens212and then may measure the geometrical dimensions of the image230with the image measurement block214. Rear view imaging setup120may form an image240through the lens222and then may measure the geometrical dimensions of the image240with the image measurement block224.

Measurement of images may be accomplished by, for example, a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) pixel matrix.

In implementations according to the present disclosure, optical properties of front view imaging setup110and rear view imaging setup120are known or previously measured. Moreover, geometrical dimensions of reference object140are also known or previously measured.

To perform the measurement of geometrical dimensions of a first measured article105, the first measured article105, the front view imaging setup110, the rear view imaging setup120, the reflective surface130, and the reference object140may be arranged in such a way that the first measured article105is located in the visual field of the rear view imaging setup120, while the reflection of the first measured article105in the reflective surface130and the reflection of the reference object140in the reflective surface130are located in the visual field of the front view imaging setup110. This may be achieved by changing the position and/or spatial orientation of one or more components of exemplary optical measurement system100as well as that of the first measured article105.

An image of the first measured article105may be formed by the rear view imaging setup120through its lens222. The dimensions of the image of the first measured article105may then be measured by the image measurement block224of the rear view imaging setup120.

Images of the reflections may be formed by the front view imaging setup110through its lens212. The dimensions of the images of the reflections of the first measured article105and the reference object140may then be measured by the image measurement block214of the front view imaging setup110.

Having dimensions of the images of the first measured article105as well as the reflections of the first measured article105and the reference object140, the geometrical dimensions of the first measured article105can be calculated. Exemplary calculations are provided below.

The spatial orientation of the components of exemplary optical measurement system100may be non-ideal, for example, having pitch and yaw, which gives an error in the geometrical measurements. To compensate for this, one or more of the components of exemplary optical measurement system100may be connected to one or more of orientation detectors150(1)-150(N), where N is a positive integer greater than or equal to one. For instance, each, one or some of the first measured article105, the front view imaging setup110, the rear view imaging setup120, the reflective surface130and the reference object140may be connected to orientation detectors150(1)-150(N), respectively. Thus, to compensate for pitch and/or yaw in one or more components of exemplary optical measurement system100, measurements from orientation detectors150(1)-150(N) may be taken into consideration when calculating the geometrical dimensions of the first measured article105.

In some implementations, some or all of front view imaging setup110, rear view imaging setup120and reference object140may be mounted in a single assembly, thus making a major part of exemplary optical measurement system100easy to handle.

FIG. 3is an optical diagram of an exemplary scenario300showing exemplary ray path in exemplary measurement system100ofFIG. 1in accordance with at least some implementations of the present disclosure.

For simplicity in description, lenses212and222are considered to be simple small aperture or pinhole “lenses”. The images230and240are formed at respective distances Q1and Q2behind the respective lenses212and222. Principal planes of lenses212and222are superimposed into a single plane H. The reference object140is also located within the plane H. The reflective surface130is flat (flat mirror) and is parallel to the plane H.

The length of the reflection of the reference object140projected through lens212of front view imaging setup110may be provided by Equation (1) as follows:

In Equation (1), A2B2is the length of the reflection of reference object140. It is equal to the length of reference object140which is A1B1and is known. Additionally, A3B3is the length of the projection measured by image measurement block214of front view imaging setup110, and X is the distance from the plane H to the reflective surface130.

The length of the reflection of the first measured article105projected through lens212may be provided by Equation (2) as follows:

In Equation (2), C2D2is the length of the reflection of the first measured article105. It is equal to the length of the first measured article105C1D1and needs to be determined. Additionally, C3D3is the length of the projection measured by image measurement block214of front view imaging setup110, and Y is the distance from the plane H to the first measured article105.

Equation (3), shown below, may be obtained by combining Equation (1) and Equation (2), as follows:

The length of the image of the first measured article105projected through lens222of rear view imaging setup120may be provided by Equation (4) as follows:

In Equation (4), C1D1is the length of the first measured article105, which the dimension of interest. Moreover, C4D4is the length of the projection measured by image measurement block224of rear view imaging setup120.

Equation (5), shown below, may be obtained by combining Equations (3) and (4) and solving C1D1, as follows:

The calculated length of the first measured article105, C1D1, is positive given the condition expressed by Inequality (6), as follows:
Q1×C4D4−Q2×C3D3≧0  (6)

Inequality (7), shown below, may be obtained by implementing Equations (2) and (4) into Inequality (6), as follows:

Inequality (7) is true for all of the practical cases.

The distance Y from the plane H to the first measured article105and the distance X+Y from the reflective surface130to the first measured article105may also be calculated.

If one or more additional measured articles, which may be a part of the first measured article105, are located at the same distance Y from the plane H, their geometrical dimensions may be determined if the one or more additional measured articles are located in the visual field of the rear view imaging setup120. Alternatively, if the one or more additional measured articles are located at the same distance X+Y from the reflective surface130, their geometrical dimensions may be determined if the reflections of the one or more additional measured articles in the reflective surface130are located in the visual field of the front view imaging setup110.

Similar calculations may be performed for optical camera lenses in places of lenses212and222with their additional optical characteristics (e.g., focal distances) taken into account.

FIG. 4is a block diagram showing an exemplary flexible mount of the imaging device for an exemplary measurement system400in accordance with at least some implementations of the present disclosure.

Exemplary measurement system400may be similar to exemplary measurement system100ofFIG. 1. Thus, in the interest of brevity, description of exemplary measurement system400is focused on differences between exemplary measurement system400and exemplary measurement system100. As shown inFIG. 4, exemplary measurement system400may be equipped with an imaging device410connected to, coupled to or otherwise mounted on an imaging device mount420. Imaging device410may have the capabilities of forming an image and measuring the geometrical dimensions of the image. Imaging device mount420may be set in a front view position. In this case imaging device410may have the functions and capabilities of front view imaging setup110as described above. Alternatively, imaging device mount420may be set in a rear view position. In this case imaging device410may have the functions and capabilities of rear view imaging setup120as described above. In some implementations, imaging device mount420may include a tripod with a rotating head.

Exemplary Implementations

In view of the above andFIG. 1-FIG. 4, a system for measuring geometrical dimensions of one or more measured articles may include: a front view imaging setup, a rear view imaging setup, a reflective surface, and a reference object. The front view imaging setup, the rear view imaging setup, the reflective surface and the reference object may be arranged in such a way that a first measured article of the one or more measured articles is located in a visual field of the rear view imaging setup, while a reflection of the first measured article in the reflective surface and a reflection of the reference object in the reflective surface are located in a visual field of the front view imaging setup.

In at least some implementations, at least one additional measured articles of the one or more measured articles may be located in the visual field of the rear view imaging setup.

In at least some implementations, a reflection of at least one additional measured article of the one or more measured articles in the reflective surface may be located in the visual field of the front view imaging setup.

In at least some implementations, the front view imaging setup may be connected to a spatial orientation detector. Additionally or alternatively, the rear view imaging setup may be connected to a spatial orientation detector. Additionally or alternatively, the reflective surface is connected to a spatial orientation detector. Additionally or alternatively, the reference object is connected to a spatial orientation detector. Additionally or alternatively, each of the one or more measured articles is connected to a respective spatial orientation detector.

In at least some implementations, the front view imaging setup and the rear view imaging setup may be mounted in a single assembly. Additionally or alternatively, the front view imaging setup and the reference object are mounted in a single assembly. Additionally or alternatively, the rear view imaging setup and the reference object are mounted in a single assembly.

In at least some implementations, the front view imaging setup may include an imaging device and an imaging device mount on which the imaging device is mounted. The imaging device mount may be set to a front view position.

In at least some implementations, the rear view imaging setup may include an imaging device and an imaging device mount on which the imaging device is mounted. The imaging device mount may be set to a rear view position.

FIG. 5is a flowchart showing an exemplary process500in accordance with at least some implementations of the present disclosure.

Exemplary process500may include one or more operations, actions, or functions as illustrated by one or more of blocks510-590. Although illustrated as discrete blocks, various blocks may be divided into additional blocks, combined into fewer blocks, or eliminated, depending on the desired implementation. Exemplary process500may be implemented by exemplary measurement system100or exemplary measurement system400. For illustrative purposes, the operations described below with respect to exemplary process500are performed by components of exemplary measurement system100. Exemplary process500may begin at block510.

Block510(Measure Optical Properties Of First Imaging Setup) may involve measuring optical properties of a first imaging setup. In some implementations, any suitable instrument, system or mechanism capable of measuring optical properties of the first imaging setup may be used to measure the optical properties of the first imaging setup in lieu of or in addition to exemplary measurement system100. Block510may be followed by block520.

Block520(Measure Optical Properties Of Second Imaging Setup) may involve measuring optical properties of a second imaging setup. In some implementations, any suitable instrument, system or mechanism capable of measuring optical properties of the second imaging setup may be used to measure the optical properties of the second imaging setup in lieu of or in addition to exemplary measurement system100. Block520may be followed by block530.

Block530(Measure Geometrical Dimensions Of Reference Object) may involve measuring geometrical dimensions of a reference object. In some implementations, any suitable instrument, system or mechanism capable of measuring geometrical dimensions of the reference object may be used to measure the geometrical dimensions of the reference object in lieu of or in addition to exemplary measurement system100. Block530may be followed by block540.

Block540(Arrange Measured Article(s) Including First Measured Article, First And Second Imaging Setups, Reflective Surface and Reference Object) may involve arranging one or more measured articles (including a first measured article), the second imaging setup, a reflective surface, the first imaging setup, and the reference object in such a way that the first measured article is located in a visual field of the second imaging setup, with a reflection of the first measured article in the reflective surface and a reflection of the reference object in the reflective surface located in a visual field of the first imaging setup. Block540may be followed by block550.

Block550(Form Image Of Reflection Of First Measured Article And Reflection Of Reference Object In First Imaging Setup) may involve exemplary measurement system100forming an image of the reflection of the first measured article and the reflection of the reference object in the first imaging setup. Block550may be followed by block560.

Block560(Form Image Of Reflection Of First Measured Article And Reflection Of Reference Object In First Imaging Setup) may involve exemplary measurement system100forming an image of the first measured article in the second imaging setup. Block560may be followed by block570.

Block570(Measure Geometrical Dimensions Of Image Formed In First Imaging Setup) may involve exemplary measurement system100measuring geometrical dimensions of the image formed in the first imaging setup. Block570may be followed by block580.

Block580(Measure Geometrical Dimensions Of Image Formed In Second Imaging Setup) may involve exemplary measurement system100measuring geometrical dimensions of the image formed in the second imaging setup. Block580may be followed by block590.

Block590(Calculate Geometrical Dimensions Of First Measured Article) may involve calculating geometrical dimensions of the first measured article. In some implementations, any suitable computing device, instrument, system or mechanism capable of calculating the geometrical dimensions of the first measured article may be used to calculate the geometrical dimensions of the first measured article.

In at least some implementations, the arranging of the one or more measured articles may further involve arranging one or more additional measured articles and the second imaging setup in such a way that the one or more additional measured articles are located in the visual field of the second imaging setup.

In at least some implementations, the arranging of the one or more measured articles may further involve arranging one or more additional measured articles, the reflective surface and the first imaging setup in such a way that reflections of the one or more additional measured articles are located in the visual field of the first imaging setup.

In at least some implementations, the calculating of the geometrical dimensions may further involve exemplary measurement system100detecting a spatial orientation of the first imaging setup.

In at least some implementations, the calculating of the geometrical dimensions may further involve exemplary measurement system100detecting a spatial orientation of the second imaging setup.

In at least some implementations, the calculating of the geometrical dimensions may further involve exemplary measurement system100detecting a spatial orientation of the reference object.

In at least some implementations, the calculating of the geometrical dimensions may further involve exemplary measurement system100detecting a spatial orientation of the reflective surface.

In at least some implementations, the calculating of the geometrical dimensions may further involve exemplary measurement system100detecting spatial orientations of the one or more measured articles.

In at least some implementations, the calculating of the geometrical dimensions may further involve calculating distances to the one or more measured articles.

In at least some implementations, the first imaging setup may be a front view imaging setup, and the second imaging setup may be a rear view imaging setup.

FIG. 6is a flowchart showing an exemplary process600in accordance with at least some implementations of the present disclosure.

Exemplary process600may include one or more operations, actions, or functions as illustrated by one or more of blocks610,620and630. Although illustrated as discrete blocks, various blocks may be divided into additional blocks, combined into fewer blocks, or eliminated, depending on the desired implementation. Exemplary process600may be implemented by exemplary measurement system100or exemplary measurement system400. For illustrative purposes, the operations described below with respect to exemplary process600are performed by components of exemplary measurement system100. Exemplary process600may begin at block610.

Block610(Set Imaging Device In Front View Position Such That Reflection Of First Measured Article In Reflective Surface And Reflection Of Reference Object In Reflective Surface Are Located In Visual Field Of Imaging Device) may involve exemplary measurement system100setting an imaging device in a front view position in such a way that a reflection of one or more measured articles including a first measured article in a reflective surface and a reflection of a reference object in the reflective surface are located in a visual field of the imaging device. Block610may be followed by block620.

Block620(Form Images Of Reflection Of First Measured Article And Reflection Of Reference Object) may involve exemplary measurement system100forming images of the reflection of the first measured article and the reflection of the reference object. Block620may be followed by block630.

Block630(Measure Geometrical Dimensions Of Formed Images) may involve exemplary measurement system100measuring geometrical dimensions of the formed images.

FIG. 7is a flowchart showing an exemplary process700in accordance with at least some implementations of the present disclosure.

Exemplary process700may include one or more operations, actions, or functions as illustrated by one or more of blocks710,720and730. Although illustrated as discrete blocks, various blocks may be divided into additional blocks, combined into fewer blocks, or eliminated, depending on the desired implementation. Exemplary process700may be implemented by exemplary measurement system100or exemplary measurement system400. For illustrative purposes, the operations described below with respect to exemplary process700are performed by components of exemplary measurement system100. Exemplary process700may begin at block710.

Block710(Set Imaging Device In Rear View Position Such That First Measured Article Is Located In Visual Field Of Imaging Device) may involve exemplary measurement system100setting an imaging device in a rear view position in such a way that a first measured article is located in a visual field of the imaging device. Block710may be followed by block720.

Block720(Form Images Of First Measured Article) may involve exemplary measurement system100forming an image of the first measured article. Block720may be followed by block730.

Block730(Measure Geometrical Dimensions Of Formed Image) may involve exemplary measurement system100measuring geometrical dimensions of the formed image.

Additional Notes