WO2000057128A1

WO2000057128A1 - Improvements in and relating to imaging

Info

Publication number: WO2000057128A1
Application number: PCT/GB2000/001014
Authority: WO
Inventors: Jurgen Dabeedin
Original assignee: The Secretary Of State For The Home Department
Priority date: 1999-03-24
Filing date: 2000-03-24
Publication date: 2000-09-28
Also published as: AU3440300A

Abstract

Apparatus and methods are provided for improved imaging, particularly of images relating to crime scenes. The apparatus provides apparatus for imaging a profile at a location, the apparatus comprising a support frame, one or more light sources for applying light to a location, a light detecting unit for detecting light from the profile, means for moving the light detecting unit relative to the location, the profile being imaged part by part if the light detecting unit is moved. The invention is particularly useful for imaging stains or marks at crime scenes, particularly in inaccessible locations.

Description

IMPROVEMENTS IN AND RELATING TO IMAGING

This invention concerns improvements in and relating to imaging, particularly, but not exclusively, to improved apparatus and methods for obtaining detailed images relating to crime scenes for subsequent use.

A wide variety of situations call for the taking of visual images at remote and/or outdoor and/or inaccessible locations for subsequent use. This is particularly true of crime scenes and other forensic situations where visual images need to be taken in a suitable form for subsequent use, for instance in making comparisons with other images or use in legal proceedings. The taking of images of footwear imprints is a particularly important field.

Existing techniques for footwear imprints etc commonly employ still photographs. The taking of such images at the scene is a technically challenging and time consuming process. In many cases small format cameras are employed, but due to the sizes of the imprints which need to be photographed, up to 14 inches or more, the resolution obtained is poor. Even where larger format cameras are used, obtaining physical access to the imprint and ensuring adequate lighting can be difficult.

The present invention aims to provide an imaging system and method which is easier to deploy, obtains high resolution images, is simple and can be provided at relatively low cost.

According to a first aspect of the invention we provide apparatus for imaging a profile at a location, the apparatus comprising a supporting frame, one or more light sources for applying light to the location, a light detecting unit for detecting light from the profile, means for moving the light detecting unit relative to the location, the profile being imaged part by part as the light detecting unit is moved. The profile may be three dimensional, such as an imprint and / or two dimensional, such as a stain. The profile may be a foot or footwear mark or imprint. The profile may be a fingerprint, handprint, earprint or other mark or imprint, for instance made by a part of a human or animal body. The profile may be a fabric mark or other surface texture. The profile may be a tyre mark, track imprint or other mark or imprint made by a vehicle. The profile may be mark or imprint on an item, location or body made by a tool, weapon or other instrument. The profile may be a fluid and / or a mark left by a fluid. The fluid may be bodily fluid, such as blood, semen, sweat or saliva. The fluid may be a natural and / or man made fluid, such as ink, wine, tea etc.

The location may be a surface, such as a floor, wall or ceiling. The location may be a part of an area, such as a piece of ground, soil, mud or the like. The location may be a part of an article, such as an item of furniture, a floor covering, clothing, a piece of glass of the like.

The support frame may be provided with one or more location engaging elements. Preferably the height of one or more of the location engaging element (s) is adjustable, ideally independently of one another, relative to the support frame. The location engaging element (s) may comprise screw threaded elements. The location engaging element (s) may comprise a releasably fastened component, the projection of which form the support frame is adjustable. The location engaging element (s) may be adjusted by varying the extent of an element which protrudes from a releasable- clamp, towards the location. The location engaging elements may be generally cylindrical in profile. Preferably the support frame is provided with three location engaging elements, ideally configured in a triangular profile.

Preferably the location engaging elements engage the location around the profile whilst the profile is being lmaged. Preferably the light sources are provided between the location engaging elements. Preferably the light detecting unit is provided between the location engaging elements. Preferably the apparatus is supported by the location on which the profile to be imaged is found. Preferably the image is taken between the location engaging elements .

The support frame preferably provides a cover. The cover may comprise a substantially planar upper component and/or one or more side walls. Preferably the cover comprises a substantially planar rectilinear upper component and four substantially planar side walls, for instance to define an open box, the opening being on the downward side. The directions may be defined relative to the imaging direction, which is generally a downward direction towards the engagement with the location.

The support frame may be provided with a carrying handle .

Preferably the apparatus, in use, has a maximum length of 50cm, more preferably less than 35cm, and/or a maximum width of 35cm, more preferably less than 25cm, and/or a maximum height, with the display means m use, of 50cm, more preferably less than 35cm, and/or a maximum height, with the display means stored, of 20cm, more preferably less than 15cm.

The apparatus may be provide with one or more light sources on the apparatus. The light source may be moveably relative to the location and/or light detecting unit, for instance to vary the manner in which the light is applied to the location, particularly where only one light source is provided.

One or more of the light sources may emit visible light and/or non-visible light, for instance ultraviolet, and / or laser and / or filtered light and / or fluorescent light. It is preferred that at least three visible light emitting sources be provided. The light sources may be lasers, light bulbs, tubes or other forms of light emitter.

Where a plurality of light sources are provided preferably at least two of the lights are provided such that they illuminate the part of the location/profile being imaged at a given time at different angles to one another. Preferably only one lighting angle is used in producing a given image.

One or more light sources may be provided which illuminates the part of the location/profile being imaged at an angle of between 70° and 90° relative to the general plane of the location and/or plane of the apparatus.

One or more light sources may be provided which illuminates the part of the location/profile being imaged at an angle of between 30° and 60° relative to the general plane of the location and/or plane of the apparatus. One light source to one side of the profile and another to the other side, preferably relative to the direction of scanning, may be provided in this way.

A light source may be provided which illuminates the part of the location/profile being imaged at an angle of between 1° and 20° relative to the general plane of the location and/or plane of the apparatus.

Preferably three illumination angles are provided, most preferably at least one in each of the listed ranges in the paragraphs above .

Preferably the profile is imaged with one light source on at a time. Further imaging runs with one of the other light sources may be provided. preferably imaging runs with each of the light sources on, ideally only one light source in each run, are provided.

Preferably the one or more light sources are mounted on and/or in a fixed relationship with the light detecting unit. Ideally the light source (s) move with the light detecting unit such that the part of the location being imaged is illuminated by light applied in a constant manner, particularly in terms of its angle of incidence.

Preferably the light detecting unit and / or light source (s) extend across the width of the location to be imaged, normally defined relative to the direction of movement of the detecting unit over the location during imaging. The light detecting unit may comprise an array of photocells .

The light detecting unit may comprise three arrays of photocells, particularly three arrays of photocells provided in lines, ideally parallel to one another. The one or more arrays of photocells may be provided with filters, particularly red, green and blue filters, such as might be used where three arrays of photocells are employed.

Preferably the amount of light detected is converted to a proportional voltage. Preferably the analogue signal arising as the voltage is converted to a digital signal for subsequent processing.

The light detecting unit, and preferably the light source (s), may be mounted on a carriage which is slideably mounted on the support frame. The carriage may be moved by a motor, preferably an electric motor. The carriage is preferably moveable by the motor in both directions. Imaging may be carried out with the carriage moving in one or both directions .

Preferably the light detecting means detect light which is non-perpendicular relative to the profile and / or plane of the light detector means movement.

Preferably the light detector means are focussed on a plane between 1 and 3cm below the level of the support frame and / or level of the light sources.

Preferably the separation between the light detecting unit and the profile is greater than 1cm, more preferably greater than 2cm, still more preferably greater than 3cm and ideally 5cm or more. The separation is preferably less than 10cm. The separation between the base of the apparatus, and / or level of the light sources, and the profile may be greater than 1cm, more preferably greater than 2cm, still more preferably greater than 3cm and ideally 5cm or more. The separation is preferably less than 10cm.

The image of the profile is preferably built up as the detecting unit is moved relative to the profile, particularly past the profile. It is preferred that the image be built up as light is applied to a part of the location and/or profile in a consistent manner and is received by the detecting unit. Preferably the image is built up sequentially as the detecting unit is moved.

Preferably the image can be displayed to the user within 1 minute of the image being taken/finished, more preferably the image can be displayed within 30 seconds. Preferably the image is stored in electronic form.

Preferably the apparatus comprises display means for the image. Preferably the display means can display the image with the apparatus in proximity to the location, and most preferably with the apparatus at the position the image was taken from. The display means may be a visual display unit, for instance part of a computer, preferably a laptop computer. The display means may be a head up display for the user.

Preferably the apparatus comprises data storage means to retain the one or more images taken. The data storage means may be provided as part of a computer, such as the hard drive, or may be associated with a computer, such as a readable storage medium, for instance a disc or diskette.

Preferably the apparatus comprises data processing means. The data processing means may be used to present the image in one or more ways, for instance different contrast levels, reversal of the image colour, magnification of a part of the image. The data processing means may be used to analyse the image, for instance the image and/or one or more details thereof may be compared with one or more existing images and/or one or more details thereof.

The display means and/or data storage means and/or data processing means may be provided by a single unit, for instance a computer, such as a laptop computer. The display means and/or data storage means and/or data processing means may be releasably mounted on the supporting frame. The display means and/or data storage means and/or data processing means may be used whilst on the support frame and/or removed from the support frame, but preferably still connected to the light detecting unit. The display means and/or data storage means and/or data processing means may be provided as an integral component of the apparatus, for instance on and/or within the support frame.

According to a second aspect of the invention we provide a method of imaging a profile at a location, the method comprising placing an imaging unit in proximity with the location, the imaging unit being supported at the location by a supporting frame, applying light to the location from one or more light sources, detecting the light from the location by a light detecting unit, the light detecting unit being moved relative to the location as the profile is imaged, the profile being imaged part by part.

The supporting frame, preferably via location engaging elements, may be positioned such that it engages the location at points around the profile during imaging. Preferably the image is taken within the outline of the support frame and/or between the location engaging elements. Preferably the light is applied to the location between the location engaging elements. Preferably the light detected by the detecting unit is received between the location engaging elements. Preferably the profile is imaged more than once. The profile may be imaged by moving the light detecting unit relative to the location in a first direction followed by imaging of the profile by moving the light detecting unit relative to the location in one or more other directions. The imaging unit orientation may be altered between imaging the profile by moving the light detecting unit in a first direction and imaging the profile by moving the light detecting unit in the second direction. Most preferably different illumination of the location/profile is provided for the different imaging runs.

The method may include the light source being move relative to the location and/or light detecting unit, for instance to vary the manner in which the light is applied to the location, particularly where only one light source is provided.

The method may use a plurality of light sources to illuminate the location/profile. Preferably the light sources are used one at a time to illuminate the location/profile .

Where two or more light sources are provided and/or a light source is moved to two or more positions, preferably the lights/positions are provided such that they illuminate the part of the location/profile being imaged at a given time at different angles to one another. A light source and/or a position for a light source may be provided which illuminates the part of the location/profile being imaged at an angle of between 70" and 90 relative to the general plane of the location and/or plane of the apparatus. A light source and/or a position for a light source may be provided which illuminates the part of the location/profile being imaged at an angle of between 30 and 60 relative to the general plane of the location and/or plane of the apparatus. A light source and/or a position for a light source may be provided which illuminates the part of the location/profile being imaged at an angle of between 1° and 20° relative to the general plane of the location and/or plane of the apparatus. Preferably three illumination angles are provided, most preferably one in each of the listed ranges.

Preferably the method includes imaging the profile with one light source on at a time. The method may be repeated with one of the other light sources on. Preferably the method is repeated with each of the light sources on, ideally only one light source in each run being on.

Preferably the light detecting unit slides relative to the support frame during imaging.

The image may be compared with one or more other images . The one or more other images may be other images taken by the method and/or images stored in a database and/or images obtained by other techniques.

The image may be compared or otherwise considered or processed in digital and / or hard copy format. Where the hard copy production resolution is lower than the imaging unit resolution, preferably the image is re-scaled prior to producing the hard copy. An imaging unit resolution of 1000dpi or greater is preferred. The hard copy producing unit may have a resolution of 350dpi or greater. Preferably the imaging unit resolution is equal to or higher in resolution than the resolution of the hard copy producing device .

The method may include the transmission of the image from the imaging unit to a data processing and / or data storage location. The image information may be conveyed to the remote location using a telephone link, preferably a digital link. The entirety of the information contained in an image may be transmitted and / or the image as displayed on the visual screen of the imaging unit may be transmitted and / or a data compression algorithm may be used to process the data for transmission. Various embodiments of the invention will now be described, by way of example only, and with reference to the accompanying drawings in which : -

Figure 1 is a perspective view of a still photograph based imprint imaging system;

Figure 2 is a perspective view of an imaging system according to one embodiment of the present invention;

Figure 3 is a schematic side cross-sectional view of one embodiment of the invention; and

Figure 4 is a schematic side cross-sectional view of a further embodiment of the invention.

In a wide variety of situations it is. desirable to be able to take a detailed imaging of a relatively small feature for subsequent consideration. Desirable images may include surface features of components, such as cracks, but are particularly important in forensic science.

Obtaining detailed images, for instance of footwear imprints, fingerprints, or other markings at a crime scene is important if the subsequent forensic consideration of those markings is to be fully carried out. Subsequent investigations may include: thorough comparison work between that image and other images with a view to obtaining a match with an image or information obtained from elsewhere; a detailed review of the manner in which the mark was made; formal presentation of the evidence in legal proceedings. In all cases it is desirable to obtain as detailed an image as possible.

A typical still photograph system is illustrated in Figure 1. The imprint 1 to be imaged is marked out by a scale 3 and requires illumination from a variety of light types, some of which are illustrated by lights 5, 7 provided on resilient, but deformable mounts 9, which are mounted on the illumination unit 11. A power supply for the illumination unit 11 is needed and is generally provided by access to mains power through lead 13. The actual image itself is taken by a large format camera 15 supported above the imprint 1 by tripod 17 and mounting 19.

As can clearly be seen from the Figure the system comes in a number of components, is both bulky and weighty and requires considerable effort to set up at the scene. The tripod in particular is problematical in many situations, for instance corners of rooms or undergrowth, where access to the imprint is very limited. The tripod is needed, however, to give stability to the system and hence avoid blurring of images .

The illustration of the full system provided according to the present invention, Figure 2, clearly shows how much more compact this imaging system is. Figures 1 and 2 are to the same scale. The imaging unit 20 itself and the accompanying laptop computer 22 take up far less room that the still photography system of Figure 1. The ability to place the unit 20 immediately over the top of the location to be imaged renders the system far more practical for inaccessible locations. At the same time the unit 20 provides a sufficiently steady system to avoid loss of resolution in the image.

As can be seen in the side cross-sectional view of Figure 3, the unit 20 comprises a generally rectangular cover 24 with side walls 26 which extend downwards to define a box, fully open on its underside 27, that is facing the area to be imaged. The cover 24 supports the laptop 22 which receives the image information from the unit 20.

The side walls 26 are provided with supports 28 which contact the ground or other surface in use. The supports 28 are provided at discrete locations around the unit 20 and only contact the ground at limited locations. This is advantageous in minimising interference of the area under consideration by the unit during the imaging process. The same supports can be used where the unit 20 is placed against a vertical wall, for instance. The lightweight nature of the cover 24 and other components, coupled with the ability to provide an elongate link to the laptop 22 which avoids the need to hold up both the unit 20 and laptop 22 assist this process .

Within the cover 24, 26 the unit is provided with a power source, generally a rechargeable battery. The power source operates the lamps and the motor 34 which drives the scanner head 36 which takes the image.

In operation, the light from the lamps shines down and illuminates the image under consideration, this light is then reflected back and reaches the photocell 37 by means of a series of mirrors and lenses 38. The lenses 38 are specially configured for the separation of the detector and the area 40 under consideration. The detail provided in Figure 3 illustrates the path taken by the light on its way to the actual photocell 37. The light intensity is converted to an electrical signal by the photocell 37. A substantial number of photocells 37, in a line, are provided on the elongate scanner head 36, the scanner head 36 spanning the width of the cover 24. As the motor advances the scanner head 36 from one end 41 of the cover 24 to the other end 42, the image of the area 40 under the cover 24, 26 is built up.

The photocell 37 schematically illustrated in Figure 3 may present three lines of photocells spanning the area 40 under consideration. A red, green and blue filtered array may be provided so as to generate a full colour image. The amount of light detected by each photocell gives rise to a voltage output which is proportional to the amount of light detected and this can readily be converted into a digital signal for subsequent processing.

The result is a full and detailed image of the area (600 dpi or higher) which can be viewed on the laptop as it is generated. The image can be stored in the memory of the laptop 22 and downloaded upon return to the laboratory or can even be transmitted via a modem from the remote location of the scene of the crime to the laboratory or elsewhere practically immediately. Comparison of the image with other images or other subsequently processing can be carried out at the location on the laptop and/or at the laboratory matching and / or elimination processes can be undertaken. The image can be inverted in terms of its contrast presentation, ie, black becomes white and vice versa. Equally the image can be considered at a number of contrast levels.

As a precursor to taking the image, a lower resolution image of the entire area potentially scanned from that position can be taken, the high resolution image may be selected from that, potentially as a small part of the whole. High resolution images only where necessary results increasing speed of scanning and ease of data handling.

As well as the ease of access given by the present invention's system, another significant problem with the prior art still photograph based systems is addressed as the images taken can immediately be reviewed on the laptop computer screen. This means that the image can be reviewed at the scene to ensure that it is complete and successful. Any problems identified in the first images can be corrected at the scene immediately and revised images taken, for instance using alternative lighting angles and / or types. Photographic based systems, however, require the images to be taken away, process and examined, before any problems are identified. This time delay is inconvenient, and may prevent a proper image being taken where access to the image at a later time is not possible. Weather or other factors may destroy the marks and in other cases it is necessary to actively destroy them, for instance in the case of blood for safety reasons.

As well as the resolution required of the scanner itself, it is very important that the image be lit properly to obtain The maximum amount of information possible. As illustrated in the embodiment of Figure 4, the unit 20 is provided with a series of lamps 50, 52, 54 mounted at different positions on the scanner head 36. As an alternative a single lamp can be provided which is physically moved to the different positions to achieve different lighting conditions. In general a different lamp is used for a given scan of the area and hence up to three, or even more, differently illuminated images of the area are obtained. The control switch 56 provided on the front of the cover 26 offers an easy means for controlling The lamp used. The lamp used could alternatively be controlled using the laptop 22.

The first lamp 50 is provided such that its light hits the part 58 of the area 40 being imaged by the scanner head 36 at that time at an angle A, of approximately 45° to the area 40. This first lamp 50 provides normal illumination as a result. As illustrated in Figure 3, two such lamps on either side of the part of the location being imaged may be provided.

The second lamp 52 is provided such that its light hits the part 58 of the area 40 being imaged at that time at an angle B, of approximately 75' to the area 40. This second lamp 52 provides direct or specular illumination as a result.

The third lamp 54 is provided such that its lit hits the part 58 of the area 40 being imaged at that time at an angle C, of approximately 10 to the area 40. The lamp 54 provides oblique illumination as a result.

Illumination in this way gives significant information about those surfaces of the imprint which are near parallel to the area 40, which are near vertical to the area 40 and angled at intermediate levels. Important information on depth and other aspects of the imprint is also obtained.

Illumination may additionally be provided at an angle of between 50° to 70°, as in Figure 3 by lamp 100. This lamp may provide specular illumination. The use of a system according to the present invention in specular illumination situations is far more effective than in conventional photography as evenly illuminating large areas using specular lighting is very difficult for conventional photographic imaging. The lighting of the present apparatus provides far more even lighting far more easily.

To obtain different images of the area 40 being imaged and / or to reduce or eliminate interference effects arising in the image, images of the area 40 to be imaged may be taken by advancing the photocell arrays in two or more different directions. The different directions may be formed by the first and second reciprocating directions of movement of the photocell arrays, but are more preferably obtained by varying the orientation of the device between imaging runs and hence varying the direction in which the photocell array is advanced.

As well as illumination from different angles, and / or different directions, illumination with different types of light is possible. Visible light and / or fluorescent light and / or ultraviolet light and / or filtered light and / or laser light for instance, may be used to reveal different features and / or details and / or information in the profile .

The scanner is particularly suited to imaging the impressions left by footwear in soft material, but can equally well be used to image imprints left by footwear which have been made visible by chemical treatment, fingerprints which have been revealed (by rendering them fluorescent, for instance) , tool markings, blood deposits or any other visual information.

To assist in some cases, such as fingerprints, a fluorescent light may be incorporated in the unit, for one or more of the lighting types discussed above.

Claims

1. Apparatus for imaging a profile at a location, the apparatus comprising a supporting frame, one or more light sources for applying light to the location, a light detecting unit for detecting light from the profile, means for moving the light detecting unit relative to the location, the profile being imaged part by part as the detecting unit is moved.

2. Apparatus according to claim 1 in which the profile is a foot mark, footwear mark, imprint, fingerprint, handprint, earprint or other mark or imprint made by a part of a human or animal body, a fabric mark, a tyre mark, track imprint or other mark or imprint made by a vehicle, a mark or imprint on an item, location or body made by a tool, weapon or other instrument.

3. Apparatus according to claim 1 or claim 2 in which the support frame is provided with one or more location engaging elements, the location engaging elements engaging the location around the profile whilst the profile is being imaged.

4. Apparatus according to any of claims 1 to 3 in which one or more of the light sources may emit visible light and/or non-visible light, for instance ultraviolet and / or fluorescent light.

5. Apparatus according to any preceding claim in which at least three visible light emitting sources are provided, the lights being provided such that they can illuminate the part of the location/profile being imaged at a given time at different angles to one another, only one light being used at a given time.

6. Apparatus according to any preceding claim in which a light source is provided which illuminates the part of the location/profile being imaged at an angle of between 70° and 90° relative to the general plane of the location and/or a light source is provided which illuminates the part of the location/profile being imaged at an angle of between 30° and 60° relative to the general plane of the location and/or a light source is provided which illuminates the part of the location/profile being imaged at an angle of between 1° and 20° relative to the general plane of the location.

7. Apparatus according to any preceding claim in which the image is stored electronically and the image can be displayed to the user within 1 minute of the image being taken/finished.