WO2008044943A1

WO2008044943A1 - Improved 3-dimensional scanning apparatus and method

Info

Publication number: WO2008044943A1
Application number: PCT/NZ2006/000259
Authority: WO
Inventors: Mihai Costache; Dale Mooney
Original assignee: Jewel Soft Holdings Limited
Priority date: 2006-10-11
Filing date: 2006-10-11
Publication date: 2008-04-17

Abstract

An apparatus for capturing 3-dimesional representations of objects. The apparatus includes a laser adapted to provide a laser projection onto the object, a mount for the laser adapted to allow the laser projection on the object to be moved over the object, a first camera adapted to capture an images of the laser projection on the object, a second camera adapted to capture an image substantially excluding the laser projection on the object, and a processor adapted to capture a sequence of images from first and second cameras. These images correspond to given stages of progression of movement of the laser projection over the object. This enables portions of images captured with the second camera to be assigned to a geometric mesh representation of the object created with images from the first camera. The invention also provides a corresponding method.

Description

IMPROVED 3-DIMENSIONAL SCANNING APPARATUS AND METHOD

TECHNICAL FIELD

The present invention relates to an improved 3-dimensional scanning apparatus and method. In particular, the invention relates to a 3-dimensional scanning apparatus and method that capture a 3-dimensional representation -of an object. More particularly, it relates to a scanning apparatus and method that captures a 3- dimensional representation of an object that represents both the geometry and photographic imagery of the object. Still more particularly the present invention relates to a 3-dimensional scanning apparatus and method that captures a 3- dimensional representation of a hand.

BACKGROUND ART

Scanning apparatus which capture 3-dimensional geometrical representations of objects are known. Typically, these involve the use of lasers to provide beams to moving mirrors which scan them over the surface of an object. Reflections of these laser beams are detected and analysed. Typically, analysis involves counting interference fringes to measure the distance from a given mirror to a point on the object where the beam is reflected from the object. If the angle of the mirror and the distance from the mirror to the point on the object are known, the geometrical position of the sample points can be deduced. Given enough sample points, a 3- dimensional geometrical representation of an object can be generated.

The analysis of interference fringes provides an accurate means for capturing 3- dimensional representations of objects. However, as will be well understood by those skilled in the art, the technology involved in moving mirrors and analysing interference fringes is relatively sophisticated and expensive. Nevertheless, these systems have found wide application. As is also understood by those skilled in the art, the analysis of distances and angles of rapidly moving mirrors is relatively processor intensive. Accordingly, a finite time is required for any given processing. To give an example, a 3- dimensinal scanned representation of an object the size of an average adult human hand (for example) using moving mirrors and interference fringe analysis may be accurate to within microns and may take approximately 2 to 5 minutes to generate.

Also known, are methods which apply surface texture to 3-dimensional geometrical representations. The aim of these is to produce relatively lifelike 3-dimensional representations of objects. Conventionally, the texture is computer generated. A choice in computer generated textures and colours may be made available to an operator to allow relatively lifelike representations to be generated.

The applicant has observed that 3-dimensional representations might be useful in applications involving the retail of goods. One particular application which has occurred to the applicant is the retail of jewellery, rings and gems. The applicant has discovered that customers in the market for an item of jewellery often have difficulty in visualising how an item which they see in a shop display, for example, will look on their person. In the case of a ring, the thickness of a band may have an impact on the overall aesthetic appearance of a customer's fingers when a given ring is placed on their own hand. For this reason, retailers attempt to carry as many different sizes and types of band as possible. However, this carries an economic cost in the form of additional inventory.

It has occurred to the applicant that a 3-dimensional representation of a customer's hand combined with a 3-dimensional representation of a jewellery ring may assist customers in making better choices or may allow retailers to carry less inventory.

The applicant has also observed that in this application it would be advantageous if there was provided a representation not only of the geometry of the customer's hand but also of the texture and possibly also the colour and tone of the hand. This representation would advantageously be combined with coloured or textured representations of rings. These aspects would interact aesthetically with the customer's choice of precious metal and gem used in making the ring.

The applicant has also observed that it would be advantageous to photographically capture the colour and texture of the customer's hand.

The applicant has further observed that a typical retail customer of jewellery rings may not require the micron type accuracy of conventional 3-dimensional scanning apparatus.

The applicant has also observed that retail customers may not be tolerant of sitting with their hand still for two to five minutes.

The applicant has yet further observed that a 3-dimensional scanner for retail applications would need to be more economical than scanners involving moving mirrors and analysis of interference fringes.

It is an object of the present invention to provide a scanning apparatus and/or method which combines a 3-dimensional geometrical representation of an object with a photographic representations of the same object, or at least to provide the public with a useful choice in scanning apparatus and methods.

It is a further object of the present invention to provide a scanning apparatus and/or method which is suited to the accuracy of 3-dimensional representations and the timeframes required for 3-dimensional representations to be used in a retail environment, or at least to provide the public with a useful choice in such scanning apparatuses and methods. It is a further object of the present invention to provide a relatively economical 3- dimensionai scanning apparatus and/or method, or at least to provide the public with a useful choice in such scanning apparatuses and methods.

All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand, or in any other country.

It is acknowledged that the term 'comprise' may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term 'comprise' shall have an inclusive meaning - i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term 'comprised' or 'comprising' is used in relation to one or more steps in a method or process.

As used herein the term 'centre of area' is intended to relate to a point which represents the centre of an area as mathematically integrated. This term is the analog of the commonly used term 'centre of mass', but relating to areas in place of masses. As used herein the term 'laser curtain' refers broadly to a laser output confined to a plane so that it forms a profile line or line of intersect when projected onto an object.

As used herein the term 'maximas' used in relation to brightness and pixels is intended to relate to a pixel or group of pixels which are the brightest as measured across a given cross section. For example, a brightness maxima for a profile line may be taken as the brightest pixel occurring on a vertical line of pixels.

As used herein the term 'photographic' and suchlike is intended to refer broadly to captured images which have photographic properties and is intended to include such images captured on any medium including CCD or other digital media.

Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.

DISCLOSURE OF INVENTION

According to one aspect the invention provides a method of capturing a 3- dimensional representation of an object, the method comprising:

projecting a laser onto the object to provide a laser projection;

providing a first camera directed towards the object, said first camera being adapted to capture an image of the laser projection on the object;

providing a second camera directed towards the object, said camera adapted to capture an image substantially excluding the laser projection;

moving the laser projection over the object; capturing a sequence of images from the first and second cameras that correspond to given stages of progression of the movement of the laser projection over the object;

creating a geometric mesh representation of the object from images captured by the first camera;

assigning portions of images captured by the second camera to the said geometric mesh.

Preferably the laser operates at an infrared wavelength.

Preferably the laser operates substantially at 780 nanometres.

Preferably the laser projection is substantially a line.

Preferably said line is provided by the projection of a laser curtain.

Preferably the method includes moving the projection of the laser curtain over the object occurs substantially along a predefined scanning axis.

Preferably the method includes moving relative to the object the laser, the first camera and the second camera.

Preferably the method includes moving the laser relative to the object comprises relative translation parallel to the scanning axis.

Preferably the method includes measuring displacement of the laser relative to the object.

Preferably the linear displacement transducer is a draw wire sensor.

Preferably the method includes creating the geometrical mesh representation of the object created from images captured from the first camera includes locating the first camera at a predefined offset angle to the laser projection and using trigonometry to detect a profile defined by the intersect of the object and the laser curtain.

Preferably the method includes detecting upon an image captured from said at least one first camera a line of brightness maximas.

Preferably the method includes creating a smoothed line representing said brightness maximas.

Preferably the method includes sampling points along said smoothed line.

Preferably the method includes providing a plurality of image capture stations each comprising a laser, a first camera and a second camera, said plurality of image capture stations arranged around the object.

Preferably said plurality of image capture stations comprises five or more said image capture stations.

Preferably the sequence of images captured from the first and second cameras comprises at least one image taken from each of first and second cameras at substantially the same stages of progression of movement of the laser projection over the object.

Preferably the method includes the step of abridging the geometric mesh representation of the object to provide an abridged geometric mesh having abridged mesh elements.

Preferably the number of abridged mesh elements is factored according to a given processing power.

Preferably the number of abridged mesh elements is factored according to the size of the object. Preferably the method includes defining for each abridged mesh element a reference point.

Preferably the reference points comprise a centre of area of the abridged mesh element.

Preferably the method includes the step of defining for the given mesh element a surface normal.

Preferably the method includes identifying for a given abridged mesh element an image from the second camera that corresponds to a stage of progression of the movement of the laser projection represented by the reference point of the given abridged mesh element.

Preferably the method includes identifying for the given abridged mesh element a single image captured from the second camera for which the surface normal of the given mesh element is most closely aligned with an orientation of a given second camera.

Preferably the method includes assigning portions of images captured by the second camera to the geometric mesh.

Preferably the method includes providing illumination for the object.

Preferably the method includes providing at least one optical filter between said light sources and the object.

Preferably the illumination is provided by a set of light sources arranged around the object.

Preferably said first camera is adapted with an optical filter adapted to attenuate visible light. Preferably said at least one second camera is adapted with an optical filter adapted to attenuate infra-red light.

Preferably the method includes aligning the plurality of lasers to provide projections lying substantially in a common plane.

Preferably the method includes a set of processor executable instructions stored on a processor readable medium, said instructions adapted to carry out the method as outlined in any one of the paragraphs above.

An apparatus for capturing a 3-dimensional representation of an object, the apparatus includes:

at least one laser adapted to provide a laser projection onto the object;

a mount for the laser, said mount adapted to allow the laser projection on the object to be moved over the object;

a first camera adapted to capture an image of the laser projection on the object;

a second camera adapted to capture an image substantially excluding the laser projection on the object;

a processor adapted to capture a sequence of images from first and second cameras, said images corresponding to given stages of progression of movement of the laser projection over the object.

Preferably the mount for the laser is also adapted to mount the first and second cameras.

Preferably the apparatus includes a translating chassis to which the mount is connected, said translating chassis being adapted to translate said mount for the laser relative to the object. Preferably the apparatus includes a plurality of said mounts including a laser, a first camera and a second camera is provided on said translating chassis.

Preferably said plurality includes five or more said mounts.

Preferably a first camera includes an optical filter adapted to attenuate visible light.

Preferably a second camera includes an optical filter adapted to attenuate infra-red light.

Preferably the second camera is located proximate a first camera.

Preferably a second camera is located along an axis parallel the predefined scanning axis from the first camera.

Preferably a first camera is located proximate each laser.

Preferably at least one camera is located along an axis parallel to the predefined scanning axis from the laser to which it is proximate.

Preferably at least one second camera is located along an axis parallel to the predefined scanning axis from the laser wavelength optimized camera to which it is proximate.

Preferably the apparatus includes a base chassis and a translator chassis, wherein the translator chassis is adapted to translate relative to the base chassis substantially along the predefined scanning axis.

Preferably the apparatus includes a means to measure the displacement of the translator chassis along the predefined scanning axis.

Preferably said means to measure displacement includes a draw wire sensor. Preferably the apparatus includes a plurality of image capture stations each including at least one laser, at least one first camera and at least one second camera disposed around the chassis.

Preferably said image capture stations are disposed substantially around the chassis.

Preferably the apparatus includes 5 or more image capture stations.

Preferably the apparatus includes one or more visible light sources mounted on the chassis.

Preferably the visible light sources include fluorescent tubes.

Preferably said fluorescent tubes are mounted substantially parallel to the central predefined scanning axis.

Preferably the apparatus includes at least one optical filter arranged between the scanning area and the fluorescent tubes.

Preferably the optical filter includes an infrared filter.

Preferably the optical filter includes a heat shield.

Preferably the optical filter is selected to compensate for deviations of the spectrum of the visible light sources from a visible white light spectrum.

Preferably the optical filter includes a minus green filter.

Preferably the apparatus includes at least one substantially annular fluorescent tube arranged transverse to the scanning axis.

Preferably the apparatus includes an adjustable mount for the laser, said mount adapted to align the output of the laser in at least two degrees of freedom. Preferably the laser mount is adapted to allow the output of a laser to be aligned into a given plane.

BRIEF DESCRIPTION OF DRAWINGS

Further aspects of the present invention will become apparent from the ensuing description which is given by way of example only and with reference to the accompanying drawings in which:

Figure 1 shows a perspective view of a scanning apparatus according to the preferred embodiment of the present invention;

Figure 2 shows an alternative perspective view of a scanning apparatus according to the same preferred embodiment as figure 1 , in this case an outer cover and frame has been removed to show internal aspects of the scanning apparatus;

Figure 3 shows a cutaway side elevation of a scanning apparatus according to the same preferred embodiment as figures 1 and 2;

Figure 4 shows a side elevation of a scanning apparatus according to the same preferred embodiment as figures 1 to 3;

Figure 5 shows an alternative perspective view of a scanning apparatus according to the same preferred embodiment as figures 1 to 4;

Figure 6 shows a further alternative perspective view of a scanning apparatus according to the same preferred embodiment as figures 1 to 5, in this case, an additional cover for an annular fluorescent tube has been removed; Figure 7 shows a further alternative perspective view of a scanning apparatus according to the same preferred embodiment as figures 1 to 6;

Figure 8 shows a yet further perspective view of a scanning apparatus according to the same preferred embodiment as figures 1 to 7;

Figure 9 shows a plan view of a scanning apparatus according to the same preferred embodiment as figures 1 to 9;

Figure 10 shows an underside plan view of a scanning apparatus according to the same preferred embodiment as figures 1 to 9;

Figure 11 depicts a method carried out according to the preferred embodiment;

Figure 12 depicts an alternative method carried out according to the preferred embodiment of the present invention.

BEST MODES FOR CARRYING OUT THE INVENTION

Figure 1 shows a scanning apparatus (1) according to the preferred embodiment of the present invention. This view of the scanning apparatus shows it as it is used in a retail environment to obtain 3-dimensional scans parts of a customer's body. For ease of reference a hand will be discussed although it will be appreciated that any body part or a whole body, or any other object, may be involved. In this scenario, the scanning apparatus (1) comprises a box (2) which has an aperture (3) into which a customer inserts their hand (not shown) and places their wrist (not shown) on a rest (4). It is envisioned that some form of rest for the fingers and palm of a hand may, be provided in alternative embodiments of the invention.

Figure 2 shows the scanning apparatus (1) with the outer cover of the box (2) and the rest (4) removed to reveal inner aspects of the scanning apparatus (1). The scanning apparatus (1 ) has a base chassis (5) and a vertical chassis or translating chassis (6). The translating chassis (6) has a front face plate (6a) and a back face plate (6b). These face plates each define a scanning aperture (7a) and (7b) which, in turn, define a scanning area (8) between the two plates.

The translating chassis (6) is mounted on horizontal guides (9) and coupled to a threaded member (10). This arrangement allows the translating chassis (6) to translate back and fourth with respect to the base chassis (5).

Figure 3 shows a cutaway side elevation of the scanning apparatus (1 ). Attached to the base chassis (5) is a drive motor (11) for the threaded member (10). A corresponding threaded member (12) is located on the translating chassis (6) to cause it to translate when threaded member (10) is turned by the drive motor (11).

The base chassis (5) has rollers (13a) to (13d) over which a screen (not shown) attached to the translating chassis (6) can be stretched.

Figure 3 also shows a laser (16a) mounted to the rear face plate (6b) via laser mount (18a) and image capture station mount (17a). Laser mount (18a) is adjustable so that the beam of a laser (16a) can be adjusted in multiple degrees of freedom. The laser (16a) includes optical elements which cause the beam to produce a laser curtain in the form of a beam combined in one plane but diverging in an orthogonal plane. The laser mount (18a) allows the laser (16a) is adjusted into a given plane so that the laser curtain is in a plane perpendicular to the axis "Z" in which the translating chassis (6) translates. This arrangement allows the laser to move, along a scanning axis relative to the scanning area (8) and allows the projection of the laser output, in the form of a laser curtain, to be moved along an object in the scanning area (8). It will be apparent to those skilled in the art that alternatives to translating the laser may be used. For example, if placed at a suitable distance the laser may be rotated or swung. However, translating is favoured in the preferred embodiment. Although not apparent from figure 3, the apparatus (1) includes a number of lasers (16) all adjusted so that their beams are confined to the same plane so they form a continuous curtain across the scanning area. (8). These additional lasers are best seen on Figures 4 and 5 as (16b) and (16c).

Also mounted on the image capture station mount (17a) is a first type of camera in the form of an infrared camera (19). The infrared camera is a digital camera which has a wavelength low pass filter to avoid saturation by visible and rear infrared light.

The infrared camera (19a) is positioned directly back from the laser in the direction 2. The infrared camera (19a) is also angled so that it is directed towards a point where the laser curtain (not shown) intersects the centre of the scanning area (8). The infrared camera (19a) is therefore offset from the laser (16a) by a predetermined angle. It will be understood by those skilled in the art that the point of intersect of the camera (19) view and the laser curtain might be adjusted if an object is to be placed off-centre with respect to the scanning area (8).

Also mounted on the image capture station mount (17a) is a second type of camera in the form of a visible wave length camera (20a). Typically the visible wavelength camera (20a) is a colour camera. This camera (20a) has a wavelength high-pass filter to alternate light at the wavelength of the laser curtain.

The cameras used in the preferred embodiment is a CCD camera with 640 x 480 or 1024 x 768 pixels. They are either black and white, for capturing the laser projection or colour for capturing the visible light image. They may have a frame rate of 60 frames per second or less. The visible wave length camera (20a) is also directly back from the laser in the scanning axis Z and is aligned to be directed at the same point of intersection between the laser curtain (not shown) and the centre of the scanning area (8).

The cameras (19) and (20) include filters so that they capture complementary images in terms of the projection of the laser curtains. This is, one captures only infrared and the other captures only visible wavelengths. The lasers are infrared, so any projection of the lasers (16) will be captured by the infrared cameras only. Alternative means for capturing complementary images will be known to those skilled in the art. For example, the two types of images (laser projection, and non laser projection) might be achieved in part with the use of chop-in amplifiers which resolve the images in respect of time rather than wavelength.

Figure 3 also shows two concentrically arranged fluorescent tubes (21 ) and (22) which direct light towards the scanning area (8).

Also shown in figure 3 is a filtering screen (23) which extends between the front face plate (6a) and back face plate (6b) and around the scanning area (8). The filtering screen consists of a number of filters to adjust the light spectrum of any light supplied from the outside of the screen (23) in towards the scanning area (8) so that the spectrum approximately corresponds to a white light spectrum. The filtering screen (23) may also include infrared filters, or heat shields, (not shown) to prevent light sources from interfering with the operation of the laser (16a) and the infrared camera (19). A typical filter to include in the filtering screen (23) is a 'minus green' filter which removes a green component from fluorescent lighting. This green component is typically more apparent when an object is viewed via the visible wave length camera (20). Therefore, the filtering screen (23) may be used to adjust not only the spectrum of light directed towards the scanning area but also to adjust the spectrum of a given visible wavelength camera (20). The translator chassis (6) has a convex section (6c) which provides a space for the fingers of the hand (not shown) when the translator chassis is in a position close to the aperture (3).

The filtering screen (23) has laser apertures, such as (24a) to (24c) shown in figure 3. These laser apertures allow for the output from the laser (16a) to project through the filtering screen (23). Otherwise, the infrared filters included in the filtering screen (23) will attenuate the output from the lasers (16) and prevent any laser light getting through to the object. The filtering screen (23) also has camera apertures (such as (25a) to (25e) shown in figure 3). The camera apertures allow the cameras (19) and (20) to view an object within the scanning area (8).

Figures 4 to 6 show a side elevation of the scanning apparatus (1). Figures 4 to 6 show a draw wire sensor (24) which is mounted on the base chassis (5). The draw wire (25) is anchored to a reference anchor (26) on the translating chassis (6). The draw wire sensor (24) provides a means to measure the displacement of the translating chassis (6) relative to the base chassis (5). Alternative means will be apparent to those skilled in the art and may include optical or machine vision means, or a variety of other electrical or optical sensors known to those skilled in the art. In particular, any linear displacement transducer known to those skilled in the art would be suitable. However, a draw wire sensor (24) is used in the preferred embodiment as it provides a simple and economical means for measuring the displacement of the translator chassis (6).

Also visible in figures 4 to 6 are a series of pairs of light sources in the form of fluorescent tubes such as (27a) to (27e). The fluorescent tubes (27) are mounted outside the filtering screen (23) and therefore provide filtered light into the scanning area (8). In the preferred embodiment, the fluorescent tubes (27) are straight tubes which project between the front face (6a) and back face (6b) of the translator chassis (6) and are mounted parallel to the axis of translation "Z'. Suitable numbers, positions and specifications of these tubes (27) will be known to those skilled in the art. The preferred embodiment has 10 pairs.

Figures 7 and 8 show a perspective view of the scanning apparatus (1) from the underside with part of the base chassis (5) removed. Visible in these figures is the drive motor (11) for the threaded member (10) which, via the action of the corresponding threaded member (12), translates the translator chassis (6) along the horizontal guides (9a) and (9b).

Figures 9 and 10 show top and bottom plane views of the scanning apparatus (1).

The use of the scanning apparatus (1) and the operation of the scanning apparatus (1) will now be described by reference to Figure 1 and with an example of use of the scanning apparatus (1) in a retail environment 1.

First, a customer places their hand (not shown) into the aperture (3) in the box (2) of the scanning apparatus (1). They then rest their wrist (not shown) on the rest (4) and hold their hand stationary in the interior of the box where it will be positioned in the middle of the scanning area (8). As discussed above, some form of rest (not shown) may be included in the scanning area for the rest of a person's hand.

Referring to figures 2 to 10 to illustrate the operation of the scanning apparatus (1), the translator chassis (6) is initially translated to a position (not shown) which is closest to the aperture (3). At this point, the user's hand (not shown) is illuminated by the fluorescent tubes, (21a), (21b) and (27a) to (27e). Also, the output from the laser (16a) project in a band around the customer's wrist near their hand (not shown). Next, the drive motor (11) causes the translator chassis (6) to move away from the aperture (3) which draws the projected band formed by the output of the lasers (16a) to (16e) and the focus of the cameras (19) and (20) to draw along and past the user's hand. During this translation, images are captured by the infrared camera (19) and visible wavelength camera (20) for processing. At the same time, the displacement of the translator chassis (6) relative to the base chassis (5), and therefore relative to the aperture (3), customers wrist (4) and hand (not shown), is measured by the draw wire sensor (24).

Figure 11 depicts a process carried out on a computer or processor associated with the scanning apparatus (1). It will be apparent to those skilled in the art which specific forms of processor are suitable for executing the steps of the process described herein and what processing power each given processor provides.

Box 101 depicts a step in which the laser (16) infrared camera (19) and visible wavelength camera (20) are directed at, say, the wrist of the customer. The lasers (16) were previously aligned by adjustment of their mounts in two degrees of freedom so that their outputs lie in a common place and form a curtain across and around the scanning area (8). The laser curtain (not shown) projects a band onto, say, the wrist of the customer. This projected band will be detected by the infrared camera (19) which is offset by a predefined offset angle (not shown) from the laser curtain. The infrared camera (19) includes a filter which attenuates visible light so the infrared camera (19) sees only the band projected onto the customer's wrist by the laser curtain. Those skilled in the art will be aware that when viewed from an offset angle, the band will reveal to the infrared camera (19) a profile of part of the customer's wrist which reveals the shape of a wrist as 'sampled' in the plane of the laser curtain (not shown).

The laser mounts (18) of the preferred embodiment consist of two brackets with 4 spacers between them. As will be understood by those skilled in the art, spacers of various lengths will allow the laser to be pointed in a suitable direction. Suitable alternative mounting arrangements will be apparent to those skilled in the art. In the preferred embodiment, the laser curtain is provided by five lasers (16a) to (16e), each providing a 60 degree diverging fan. These are located at a sufficient radius from the scanning area (8) so that a continuous laser curtain is provided for a scanning area (8) large enough to accommodate a large hand.

The lasers of the preferred embodiment operate at an infrared wavelength of 780 nanometres.

At the step depicted by box 102, the translator chassis (5) begins translating away from the wrist towards the fingers (not shown). This may typically be achieved by powering the drive motor (11).

At the step denoted by box 103 a train of clock pulses is started. Typically, the clock pulses may be at a frequency of fifteen Hz.

At the step denoted by box 104 an image is captured from each of the five infrared cameras (19a) to (19e) and stored. The image is taken at each clock pulse.

At the step denoted by box 105, an image is captured from the visible wavelength cameras (20a) to (2Oe) upon the same clock pulse. Therefore, the visible wavelength camera images and the infrared wavelength images are synchronized. This means that pairs of the images of the first and second types of camera will correspond to a given stage of progression of translation of the projected band over the hand. In fact, there are 5 sets of cameras so there will be 5 pairs or sets of these images. Each set will have been taken from a different orientation however and will see different aspects of the hand at the same stage of progression.

At the step denoted by box 106, a reading is taken from the draw wire sensor (24) to be stored with the images captured from the cameras (19) and (20) to represent the position along the axis 'Z' to which each picture corresponds. This process is repeated until typically a sequence of 150 images are taken by each camera. That is, 750 infrared images and 750 visible wavelength images due to there being 5 image capture stations.

At the step denoted by box 107 the drive motor (11) is turned off or reversed to move the translating chassis back to the starting position near the aperture (3). The drive motor (11), threaded member (10) and frequency of the clock pulses (103) are, in the preferred embodiment, arranged so that 150 images are captured by each of the cameras (19a) to (19e) and (20a) to (2Oe). There will be a visible wavelength image for each infrared wavelength image. These will be stored with the measurement taken from the draw wire sensor at each corresponding clock pulse. Also stored with this data is the angle of orientation of each camera around the translating chassis (6). For example, there will be five different angles corresponding to each pair of infrared and visible wavelength cameras.

Figure 12 depicts at a high level a process used to generate 3-dimensional representation of an object captured with the scanning apparatus (1). This process depicted in figure 12 generates a geometrical mesh from images captured by the infrared cameras (19) and assigns portions of images captured by the visible wavelength cameras to elements of the geometrical mesh. It will be apparent to those skilled in the art how each step in the process depicted in figure 12 might be implemented.

At the step depicted by step 201 the images captured in the process depicted in figure 11 are provided in a storage medium in a form apparent to those skilled in the art.

At step 202 the images from the infrared cameras are analysed to find the pixels in each vertical column of pixels which is the brightest and therefore represents a 'brightness maximas'. It will be apparent to those skilled in the art that columns of pixels may be grouped and that columns may be substituted for bands that are off- vertical.

In steps 203 a smoothing algorithm is applied to the pixels identified as a 'brightness maximas' to create a smooth line of 'brightness maximas'. This line represents the profile in the 'X' and 'Y' coordinate axis sampled along the given 'Z. Here, 'Z' is provided by the reading from the draw wire sensor taken at the clock pulse 102 corresponding to the infrared image being analysed. It will be apparent to those skilled in the art that an analogue signal from the draw wire sensor may actually be used to generate the clock pulses.

At step 205 the smoothed line formed from brightness maximas is sampled to find 'X' and Υ' coordinates for sample points. These are stored with the corresponding 'X' coordinate provided by the draw wire sensor (24) to create vertices for mesh elements that form a complete mesh representing the hand. The points are then used as vertices of mesh elements to form a 3-dimensional geometric mesh.

Typically at this point there might be approximately 200,000 mesh elements representing the customer's hand. This number of mesh elements may be larger than is required for retail purposes and will likely take longer to generate than is ideal for a retail situation.

At step 206 an abridged set of mesh elements is created. The number of mesh elements in the abridged set of mesh elements is factored to the size of the hand. For example a small hand may be represented by perhaps 25,000 mesh elements, whereas a large hand comprise 40,000 mesh elements or triangles. The size of the hand can be calculated by any suitable means apparent to those skilled in the art. A given level of processing power available to the apparatus and method of the preferred embodiment may be used to scale the number of mesh elements, in place of the hand size. At step 207 a given abridged mesh element is assigned a reference point which is, in the preferred embodiment, the centre of area of the mesh. Those skilled in the art will be aware of algorithms for finding the centre of area but these will typically involve integrating the area. Those skilled in the art will also recognise that the centre of area is an analogous term to 'centre of mass'.

At step 208 each abridged mesh element will be assigned a surface normal, which those skilled in the art will recognise as simply a unit vector which is orthogonal to the surface of the mesh element. The reference point or centre of mass would be represented by 'X', 'Y' and also 'Z' coordinates.

At step 209 the 'Z' coordinate of the reference point of the given abridged mesh element is used to find the closest 'Z' coordinate assigned to a set of visible wavelength camera images. This image will best correspond to the stage of progression of the laser projection over the object. In the case of these images, the 'Z' coordinate is supplied by the draw wire sensor and clock pulse 102. However, in the case of the abridged mesh element, this 'Z' measurement will have been lost during the abridgment process. Hence, the centre of area reference point is used to supply a 'Z' coordinate.

Step 209 identifies five visible wavelength images which have a 'Z' coordinate corresponding to that of the reference point for the given abridged mesh element.

At step 210 a single visible wavelength image is selected as corresponding to the given abridged mesh element by comparing the surface normal assigned to the given abridged mesh element with the angle assigned to the visible wave length image by the associated camera (20a) to (2Oe).

At this point the given abridged mesh element, which has essentially been captured with the infrared cameras (19a) to (19e) and lasers (16a) to (16e) before the abridgment process, is associated with a visible wavelength image which will have the portion of the hand that is covered by the abridged mesh element approximately squarely in the centre of the visible wave length image.

At step 211 the vertices of the abridged mesh element and the visible wavelength image are input into an algorithm which is known to those skilled in the art to assign pixels from the visible wavelength image to the abridged mesh element.

Steps 207 to 211 are repeated until pixels from visible wavelength images have been assigned to suitable parts of each of the abridged mesh elements.

Step 212 represents the end of the process. At this point, a 3-dimensional representation of the hand is provided and this representation includes visible wavelength images or photographic type images of portions of the hand. Therefore, the shape of a hand will be captured in 3-dimensions along with the colour, tone and texture of the hand. For example, the person's skin tone, including colouration and texture created by veins and hairs will be captured in the 3-dimensional representation of the hand.

This 3-dimensional representation will be suitable for use in displaying goods such as rings or gems which interact aesthetically with the dimensions, colour, tone and texture of the hand to allow an informed retail decision on a ring and gem which a given customer finds aesthetically pleasing.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims.

Claims

WHAT I/WE CLAIM IS:

1. A method of capturing a 3-dimensional representation of an object, the method comprising:

projecting a laser onto the object to provide a laser projection;

moving the laser projection over the object;

capturing a sequence of images from the first and second cameras, said images corresponding to given stages of progression of the movement of the laser projection over the object;

2. The method of claim 1 or claim 2, wherein the laser projection substantially forms a line.

3. The method of claim 2, wherein said line is provided by the projection of a laser curtain.

4. The method of any one of claims 1 to 3, wherein moving the projection of the laser curtain over the object occurs substantially along a predefined scanning axis.

5. The method of any one of claims 1 to 4, wherein the method includes moving relative to the object the laser, the first camera and second camera.

6. The method of any one of claims 1 to 5, wherein moving the laser relative to the object comprises translating the laser relative to the object, said translation being parallel to the scanning axis.

7. The method of claim 6 including measuring displacement of the laser relative to trie object.

8. The method of claim 7 wherein the linear displacement is measured by a draw wire sensor.

9. The method of any one of claims 1 to 8, wherein creating the geometrical mesh representation of the object from images captured from the first camera includes locating the first camera at a predefined offset angle to the laser projection and using trigonometry to detect a profile defined by the intersect of the object and the laser curtain.

10. The method of claim 9, including detecting upon an image captured from said first camera a line of brightness maximas.

11. The method of claim 10 including creating a smoothed line representing said brightness maximas.

12. The method of claim 11 including sampling points along said smoothed line.

13. The method of any one of claims 1 to 12 including providing a plurality of lasers arranged around the object.

14. The method of any one of claims 1 to 13, wherein the method includes providing a plurality of image capture stations each comprising, a first camera and a second camera, said plurality of image capture stations being arranged around the object.

15. The method of claim 12 or claim 13, wherein said plurality comprises five or more.

16. The method of any one of claims 1 to 15, wherein the sequence of images captured from the first and second cameras comprises at least one image taken from each of first and second cameras at substantially the same stages of progression of movement of the laser projection over the object.

17. The method of any one of claims 1 to 16 wherein the geometric mesh comprises mesh elements.

18. The method of claim 17, including defining a reference point for each mesh element.

.

19. The method of claim 18, wherein the reference points comprise a centre of area of the abridged mesh element.

20. The method as claimed in any one of claims 17 to 19, including the step of defining a surface normal for each mesh element.

21. The method of any one of claims 17 to 20, including identifying for a given mesh element images from the second camera that best correspond to a stage of progression of the movement of the laser projection represented by the reference point of the given abridged mesh element.

22. The method of claim 21 , including identifying for the given mesh element a single image captured from the second camera for which the surface normal of the given mesh element is most closely aligned with an orientation of a given second camera.

23. The method as claimed in claim 21 wherein assigning portions of images captured by the second camera to the geometric mesh includes assigning portions of the single image captured by the second camera to the mesh element.

24. The method of any one of claims 1 to 23, including the step of abridging the geometric mesh representation of the object to provide an abridged geometric mesh having abridged mesh elements.

25. The method of claim 24, wherein the number of abridged mesh elements is factored according to a given processing power.

26. The method of claim 24, wherein the number of abridged mesh elements is factored according to the size of the object.

27. The method of any one of claims 1 to 26 including providing illumination for the object.

28. The method as claimed in claim 27 including providing at least one optical filter between said light sources and the object.

29. The method of claim 27 or claim 28, wherein the illumination is provided by a set of light sources arranged around the object.

30. The method as claimed in any one of claims 1 to 29, wherein said first camera is adapted with an optical filter adapted to attenuate visible light.

31. The method as claimed in any one of claims 1 to 30, wherein said at least one second camera is adapted with an optical filter adapted to attenuate infra-red light.

32. The method of any one of claims 13 to 31 including aligning the plurality of lasers to provide projections lying substantially in a common plane.

33. A set of processor executable instructions stored on a processor readable medium, said instructions adapted to carry out the method of any one of claims 1 to 32.

34. An apparatus for capturing a 3-dimensional representation of an object, the apparatus including:

at least one laser adapted to provide a laser projection onto the object;

a mount for the laser, said mount adapted to allow the laser projection to be moved over the object;

a second camera adapted to capture an image substantially excluding the laser projection on the object; a processor adapted to capture a sequence of images from first and second cameras, said images corresponding to given stages of progression of movement of the laser projection over the object.

35. The apparatus of claim 34, wherein the mount for the laser is also adapted to mount the first and second cameras.

36. The apparatus of claim 35, including a translating chassis to which the mount is connected, said translating chassis being adapted to translate said mount for the laser relative to the object.

37. The apparatus of claim 36, including a plurality of said mounts including a laser, a first and a second camera is provided on said translating chassis.

38. The apparatus of claim 37, wherein said plurality includes five or more said mounts.

39. The apparatus of any one of claims 34 to 38, wherein a first camera includes an optical filter adapted to attenuate visible light.

40. The apparatus of any one of claims 34 to 39, wherein a second camera includes an optical filter adapted to attenuate infra-red light.

41. The apparatus of any one of claims 34 to 40, wherein the second camera is located proximate a first camera.

42. The apparatus of any one of claims 34 to 41 , wherein a second camera is located along an axis parallel the predefined scanning axis from the first camera.

43. The apparatus of any one of claims 34 to 42, wherein the first camera is located proximate each laser.

44. The apparatus of claim 43, wherein at least one camera is located along an axis parallel to the predefined scanning axis from the laser to which it is proximate.

45. The apparatus of claim 44, wherein at least one second camera is located along an axis parallel to the predefined scanning axis from the laser wavelength optimized camera to which it is proximate.

46. The apparatus of claim 45, wherein the laser operates substantially at an infrared wavelength.

47. The apparatus of claims 46, wherein the laser operates substantially at 780 nanometres.

48. The apparatus of any one of claims 34 to 47, including a base chassis and a translator chassis, wherein the translator chassis is adapted to translate relative to the base chassis, said translation being substantially along the predefined scanning axis.

49. The apparatus of claim 48, including a means to measure the displacement of the translator chassis along the predefined scanning axis.

50. The apparatus of claim 49, wherein said means to measure displacement includes a draw wire sensor.

51. The apparatus of any one of claims 34 to 50, including a plurality of lasers arranged around the object.

52. The apparatus of any one of claims 34 to 51 , including a plurality of image capture stations each including at least one first camera and at least one second camera disposed around the chassis.

53. The apparatus of claim 52, wherein said image capture stations are disposed substantially around the chassis.

54. The apparatus of claim 53, including 5 or more image capture stations.

55. The apparatus of claim 54, including one or more visible light sources mounted on the chassis.

56. The apparatus of claim 55, wherein the visible light sources include fluorescent tubes.

57. The apparatus of claim 56, wherein said fluorescent tubes are mounted substantially parallel to the central predefined scanning axis.

58. The apparatus of any one of claims 55 to 57, including at least one optical filter arranged between the scanning area and the fluorescent tubes.

59. The apparatus of claim 58, wherein the optical filter includes an infrared filter.

60. The apparatus of claim 59, wherein the optical filter includes a heat shield.

61. The apparatus of claim 59 or claim 60, wherein the optical filter is selected to compensate for deviations of the spectrum of the visible light sources from a visible white light spectrum.

62. The apparatus of claim 61 , wherein the optical filter includes a minus green filter.

63. The apparatus of any one of claims 55 to 62, including at least one substantially annular fluorescent tube arranged transverse to the scanning axis.

64. The apparatus of any one of claims 34 to 63 including an adjustable mount for the laser, said mount adapted to align the output of the laser in at least two degrees of freedom.

65. The apparatus of claim 64 wherein the laser mount is adapted to allow the output of a laser to be aligned into a given plane.

66. A method of capturing a 3-dimensional representation of an object substantially as herein described and illustrated with reference to the accompanying drawings.

67. A set of computer executable instructions adapted to carry out a method substantially as herein described and illustrated with reference to the accompanying drawings.

68. An apparatus for capturing a 3-dimensional representation of an object substantially as herein described and illustrated with reference to the accompanying drawings.