WO2019119038A1

WO2019119038A1 - System and method for generating a virtual representation of a security document

Info

Publication number: WO2019119038A1
Application number: PCT/AU2018/051359
Authority: WO
Inventors: Gary Fairless Power
Original assignee: Ccl Secure Pty Ltd
Priority date: 2017-12-19
Filing date: 2018-12-19
Publication date: 2019-06-27

Abstract

A method of generating a virtual representation of a security document, the security document having one or more security features, including: using a camera to capture fiducial markings on or within a substrate for physically representing the security document; using a position sensing mechanism to detect the viewing position of a user; using a data processing device to compute the relative position and orientation of the substrate from the viewing position; using a data storage device to store data characterising the security document and the or each security features; using the data processing device to compute the virtual representation of the security document and the or each security feature as it would be seen by the user; and using an display mechanism to display the virtual representation of the security document as it would be seen by the user.

Description

Title of Invention

System and Method for Generating a Virtual Representation of a Security Document

Technical Field

[0001] The invention relates generally to security documents in which security features are used as anti-counterfeiting measures. Embodiments of the invention are applicable to security documents such as bank notes, credit cards, cheques, passports, identity cards and the like, and it will be convenient to describe the invention in relation to these exemplary, non-limiting applications.

Background of Invention

[0002] It is well-known that many of the world's bank notes bear security devices or features which produce optical effects enabling a visual authentication of the bank note. Such security devices or features may be provided in or on a substrate from which the bank note is formed, and/or in or on one or more layers of material applied to the substrate. The security devices or features may take a wide variety of forms such as security threads embedded in layers of the bank note, security inks, printed or embossed features including relief structures, interference layers, liquid crystal devices, lenses, mirrors and other structures that cause light to be focussed towards, diverged from or constructively interfere with a real or imaginary focal point, optically variable devices (OVDs) and the like. The bank note substrate may be at least partially transparent, or include an at least partially transparent window or half window which enables various security devices or features to be viewed in transmission and/or reflection, and also for the security devices or features to interact with each other in the production of the optical effect used for visual authentication of the bank note.

[0003] Before a bank note design is put into production, a full "mock up" bank note is often produced in order to verify the visual look of the design and various security devices or features incorporated into the bank note. Ideally, the mock up bank note is also used to demonstrate to potential customers the optical effects produced by the various security devices and features in the bank note, so that selected security devices and features can be included or excluded or altered in some way before the bank note is finally produced and put into circulation. The time taken and cost to produce a mock up bank note is very significant. In many cases, it is simply not viable to produce a mock up bank note which accurately reflects the final design of some security features, especially those which require significant investment in tooling. Accordingly, the first time that the bank note designers and/or customer sees the final bank note and the various security features or devices is often when the first production run is made. This is particularly true of OVD security features which rely upon the interaction of light with three dimensional structures in the bank note to produce an optical effect used for authentication purposes.

[0004] It would be desirable to provide a method and system to verify the aesthetics and/or performance of the various optical effects produced by the security devices or features in a bank note or other security document that was more rapid, less costly and more convenient than currently available methods and systems.

[0005] It would also be desirable to provide a method and system for verifying the aesthetics and/or performance of security devices or features in a bank note or other security document and to enable the modification or redesign of the bank note or other security document, in a manner that ameliorates or overcomes one or more inconveniences or disadvantages of the prior art.

Summary of Invention

[0006] One aspect of the invention provides a method of generating a virtual representation of a security document, the security document having one or more security features, including: using a camera to capture fiducial markings on or within a substrate for physically representing the security document, the fiducial markings having a known correspondence to the extent of the substrate; using a position sensing mechanism to detect the viewing position of a user; from the relative positions of the fiducial markings to each other, and from the detected viewing position, using a data processing device to compute the relative position and orientation of the substrate from the viewing position; using a data storage device to store data characterising the security document and the or each security features; from the relative position and orientation of the substrate from the viewing position and from the stored data, using the data processing device to compute the virtual representation of the security document and the or each security feature as it would be seen by the user; and using an display mechanism to display the virtual representation of the security document as it would be seen by the user.

[0007] Another aspect of the invention provides a system for generating a virtual representation of a security document, the security document having one or more security features, including: a camera to capture fiducial markings on or within a substrate for physically representing the security document, the fiducial markings having a known correspondence to the extent of the substrate; a position sensing mechanism to detect the viewing position of a user; a data processing device to compute the relative position and orientation of the substrate from the viewing position from the relative positions of the fiducial markings to each other, and from the detected viewing position; a data storage device to store data characterising the security document and the or each security features, wherein the data processing device further computes the virtual representation of the security document and the or each security feature as it would be seen by the user from the relative position and orientation of the substrate from the viewing position; and a display mechanism to display the virtual representation of the security document as it would be seen by the user.

[0008] In one or more embodiments, the position sensing mechanism includes the same or a different camera for capturing an image of the users head. [0009] In other embodiments, the position sensing mechanism includes a position sensor directly or indirectly affixed to the user’s head. For example, the position sensor may form part of an Inertial Measurement Unit (IMU).

[0010] In one or more embodiments, the display mechanism includes a projector for projecting the virtual representation of the optical effect, as it would be seen by the user, onto the substrate.

[0011] In one or more embodiments, the substrate is at least partially transparent.

[0012] In other embodiments, the substrate is opaque and the virtual

representation of the optical effect is projected onto a virtual window area of the substrate.

[0013] In yet other embodiments, the substrate is partially opacified except in a transparent or partially transparent window region, and the virtual representation of the optical effect is projected onto the window region of the substrate.

[0014] In one or more embodiments, the display mechanism includes a virtual headset for the displaying the virtual representation of the optical effect as it would be seen by the user.

[0015] In one or more embodiments, the fiducial markings are on first surface of the substrate facing the user.

[0016] In other embodiments, the fiducial markings are on a second surface of the substrate facing away from the viewer, and substrate is at least partially transparent to light able to be detected by the camera.

[0017] In yet other embodiments, the fiducial markings are within the substrate, and substrate is at least partially transparent to light able to be detected by the camera.

[0018] In one or more embodiments, the or each security feature characterised by the stored data generates a micro-optical effect visible to the user. The micro-optical effect may be visible to the user when light is transmitted through the substrate to the user. The micro-optical effect may also or alternatively be visible to the user when light is reflected from the substrate to the user. [0019] In one or more embodiments, the micro-optical effect is not observable in visible light but is observable in infrared or ultraviolet light.

[0020] In one or more embodiments, the micro-optical effect is only visible to the user at particular relative angles of orientation between the security document and the user, notably due to obstructive or moire effects.

[0021] In one or more embodiments, the stored data characterises an optically variable device (OVD).

Definitions

Security Document or Token

[0022] As used herein, the terms security documents and tokens includes all types of documents and tokens of value and identification documents including, but not limited to the following: items of currency such as bank notes and coins, credit cards, cheques, passports, identity cards, securities and share certificates, driver's licences, deeds of title, travel documents such as airline and train tickets, entrance cards and tickets, birth, death and marriage certificates, and academic transcripts.

[0023] The invention is particularly, but not exclusively, applicable to security devices, for authenticating items, documents or tokens, such as bank notes, or identification documents, such as Identity cards or passports, formed from a substrate to which one or more layers of printing are applied.

Security Device or Feature

[0024] As used herein, the term security device or feature includes any one of a large number of security devices, elements or features intending to protect security document or token from counterfeiting, copying, alteration or tampering. Security devices or features may be provided in or on the substrate of the security document or in or on one or more layers applied to the base substrate, and may take a wide variety of forms such as security threads embedded in layers of the security document; security inks such as fluorescent, luminescent or phosphorescent inks, metallic inks, iridescent inks, photochromic, thermochromic, hydrochromic, or peizochromic inks; printed or embossed features including relief structures; interference layers; liquid crystal devices; lenses and lenticular structures; optically variable devices (OVDs) such as diffractive devices including diffraction gradients, holograms and diffractive optical elements (DOEs).

Substrate

[0025] As used herein, the term substrate refers to the base material from which the security document or token is formed. The base material may be paper or other fibrous materials such as cellulous; a plastic or polymeric material including but not limited to polypropylene (PP), polyethylene (PE), polycarbonate (PC), polyvinyl chloride (PVC), polyethylene terephthalate (PET), biaxially-oriented polypropylene (BOPP); or a composite material of two or more materials, such as a laminate of paper and at least one plastic material, or of two or more polymeric materials.

Transparent Windows and Half Windows

[0026] As used herein, the term window refers to a transparent or translucent area in the security document compared to the opaque region to which printing is applied. The window maybe fully transparent so as to allow the transmission of light substantially unaffected, or it may be partly transparent or translucent, partly allowing the transmission of light but without allowing objects to be seen clearly through the window area.

[0027] A window area may be formed in a polymeric security document which has at least one layer of transparent polymeric material and one or more opacifying layers applied to at least one side of a transparent polymeric substrate, by omitting at least one opacifying layer in the region forming the window area. If opacifying layers are applied to both sides of a transparent substrate, a fully transparent window may be formed by omitting the opacifying layers on both sides of the transparent substrate in the window area.

[0028] A partly transparent or translucent area herein after referred to as a "half window", may be formed in a polymeric security document which has opacifying layers on both sides by omitting the opacifying layers on one side only of the security document in the window area so that "half-window" is not fully transparent but allows sunlight to pass through without allowing objects to be viewed clearly through the half window.

[0029] Alternatively, it is possible for the substrates to be formed from a substantially opaque material, such as paper or fibrous material, without an insert of transparent plastics material inserted into a cut out or recessed into the paper or fibrous substrate to form a transparent window or a translucent half-window area.

Opacifying Lavers

[0030] One or more opacifying layers may be applied to a transparent substrate to increase the opacity of the security document. An opacifying layer is such that LT LO where Lo is the amount of light incident on the document, and LT is the amount of light transmitted through the document. An opacifying layer may comprise any one or more of a variety of opacifying coatings. For example, the opacifying coatings may comprise a pigment, such as titanium dioxide, dispersed within a binder or carrier of heat- activated cross-linkable polymeric material. Alternatively, a substrate of transparent plastic material could be sandwiched between opacifying layers of paper or other partially or substantially opaque material to which indicia may be subsequently printed or otherwise applied.

Focusing Elements

[0031] One or more focusing elements may be applied to the substrate of the security device. As used herein, the term "focusing element" refers to devices that focus light towards, or cause light to be diverged from or constructively interfere at a real or imaginary focal point. Focusing elements include refractive lenses that focus incoming light to a real focal point in a real focal plane or to a virtual focal point in a virtual focal plane and also collimate light scattered from any point in the focal plane to a particular direction. Focusing elements also include convex reflective elements having a virtual focal point where incoming substantially collimated light appears to diverge from that single virtual focal point. Focusing elements also include transmissive or reflective diffractive lenses, zone plates and the like that cause the transmitted or reflected diffracted light to constructively interfere at a desired real or virtual focal point.

Brief Description of Drawings [0032] Preferred embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which:

[0033] Fig. 1 is a cross-sectional view of part of a bank note including multiple security features for producing a number of optical effects to verify the authenticity of the bank note;

[0034] Figs. 2 and 3 are cross-sectional views of parts of two bank notes in which half windows and full windows are formed, and which include security features that may be viewed in transmission and/or reflection;

[0035] Figs. 4 to 6 are representations of three different embodiments of a substrate onto which may be projected a virtual representation of part or all of a finished bank note or other security document;

[0036] Figs. 7 and 8 are schematic diagrams depicting various elements of a first embodiment of a system for generating a virtual representation of a security document;

[0037] Fig. 9 is a schematic diagram illustrating the manner in which a data processing device forming part of the system shown in Figs. 7 and 8 computes the virtual representation of the security document or part of the security document as it would be seen by a user;

[0038] Fig. 10 is a flow chart depicting a sequence of operations performed by the system shown in Figs. 7 and 8;

[0039] Figs. 1 1 and 12 are schematic diagrams of elements of a second embodiment of a system for generating a virtual representation of a security document;

[0040] Fig. 13 is a schematic diagram of a variation to the embodiment of the system for generating a virtual representation of a security document depicted in Figs. 1 1 and 12; and

[0041] Fig. 14 is a flow chart depicting a sequence of operations performed by the embodiments shown in Figs. 1 1 to 13. Detailed Description of the Drawings

[0042] Fig. 1 shows an exemplary cross-sectional view of a bank note 10 including a transparent or partially transparent substrate 12. On a first side of the substrate 12 are formed opacifying layers 14 to 18. Corresponding openings are created in each of the layers 14 to 18 to form a window 20, namely a transparent or translucent area in the security document 10 when compared to the opaque region immediately surrounding the window 20.

[0043] A security thread 22 extending across the depth of the bank note 10 is formed in the opacifying layer 14. The exemplary bank note 10 also includes a layer 24 of printed ink over which is applied a layer 26 of ink that is only visible in the presence of UV or infrared light. The exemplary bank note 10 further includes three dimensional structures 28 and 30, such as a diffraction grating or diffractive optical element (DOE). Diffraction gratings produce optically variable effects, and DOEs provide authentication when viewed by a point light source, such as a laser or LED.

[0044] Three dimensional structures, such as these, are often required to be extremely fine, often in the micron or sub-micron range, and the scale shown in Fig. 1 is not representative. The method of creating such structures involves creation of “masters” using techniques such as e-beam (electron beam) lithography, direct laser writing and other micro-manufacturing and nanofabrication technologies. Once a master has been created, in known further processes, a sheet metal tool, known as a shim is produced. The entire process can be expensive and time consuming.

[0045] Applied directly to the substrate 12 in the window region 20 of the first side of the substrate 12 is additionally an optically variable device 32, for example, a device that may produce a hologram when viewed in the presence of light transmitted through the substrate 12.

[0046] On the opposite side of the substrate 12 is formed a layer of coloured ink 34, once again leaving a window 36, formed by a gap in the printed layer 34, that is superposed with the window 20 in the exemplary bank note 10. On top of the coloured layer of material 34 is printed in opacifying layer 36 and a further layer of coloured ink 38 and additional layer 40 of material only visible in the presence of UV or infrared light is also applied to the bank note 10. [0047] A printed design 42 is applied in one or more areas on the second side of the substrate 42, whilst a further three dimensional structure 44 is applied elsewhere on the second side of the substrate 12 to produce an optically variable effect visible to a user, such as a latent image.

[0048] It will be appreciated that the exemplary bank note 10 depicted in Fig. 1 is merely illustrative of the materials and structures that may be applied to a substrate used to form a bank note and which collectively provide multiple security features used to authenticate the bank note. Fig. 1 is intended to show the complexity of the security features that are used in the manufacture of modern bank notes and to illustrate the costly and time consuming nature of producing a fully mocked up bank note using conventional manufacturing techniques prior to a full production run.

[0049] It will also be appreciated that some of the optical effects produced by the bank note 10 are intended to be seen in light transmitted through the substrate, whereas other effects are intended to be seen in reflected light. Yet other optical effects result from both light that is reflected from the bank note and transmitted through the bank note simultaneously.

[0050] Accordingly, Fig. 2 represents an exemplary bank note 60 including a substrate 62 and layers 64 and 66 of opacifying material, such as printed ink. A first window 68 is formed in the layer 64 of material applied to a first side of the substrate 62 and light transmitted through the window 68 is reflected from an opposing side of the substrate 62 to a viewer 70. A further window 71 is formed in the layer 64 of material, however, in this case a corresponding window 72 is formed in the layer 66 of material so that the two windows are superposed. A layer 74 of partly opacified material is applied in the window 72 so that when a user views the bank note 60 from a position 76 an optical effect is barely or not discernible from the window 72, however when viewed from a user position 78, an optical effect is generated both by light transmitted through the window 70 and reflected from the layer 74 and from light transmitted through the opacifying layer 74 and substrate 62 to the user at the position 78.

[0051] Fig. 3 depicts a similar arrangement in which an exemplary bank note 80 includes two superposed window regions 82 and 84. A layer 86 of opacified material is formed in the window region 84, whilst a layer 88 of opacifying material is formed in the window region 82. However, in this case, regions are removed from the opacifying 88 to form a pictorial design that is not discernible from a viewer at position 90, but is discernible to a viewer at position 92 when viewing the bank note 80 in light transmitted through the substrate 94.

[0052] Fig. 7 depicts one embodiment of a system 100 for generating a virtual representation of a bank note or other security document, including one or more security features of the type depicted in Figs. 1 to 3. The system 100 includes a camera 102 to capture fiducial markings 104 to 1 10 formed on or within a substrate 1 12 for physically representing part or all of the bank note or other security document that will subsequently be manufactured. The fiducial markings 104 to 1 10 have a known correspondence to the extent of the substrate 112 such that detection of the fiducial markings 104 to 1 10 enables the position and orientation of the substrate to be determined.

[0053] The system 100 further includes a position sensing mechanism to detect the viewing position of a user. As seen in Fig. 8, the position sensing mechanism may include the same camera 102, or in alternate embodiments may include a different camera, for capturing an image of or key reference points relating to a user's head 1 14. Data from the camera 102 is transmitted via interconnected wireless

communication devices 1 16 and 1 18, or other data link, to a data processing device 120.

[0054] The data processing device 120 includes a conventional input/output module, a data processing unit 124, a main memory 126 for storing computer software in the form of a series of instructions to cause the data processing unit 122 to carry a desired functionality. A secondary memory 128 is provided to store data used to carry out the series of instructions, such as data captured by the camera 102. In addition, a user display 130 and corresponding display interface 132, as well as user input devices 134 and 136 (in this case a keyboard and mouse) and associated input output interface 138 are also provided as part of the data processing device [0055] The data processing device 120 acts to compute the relative position and orientation of the substrate 1 12 from the viewing position of the user 1 14 from the relative positions of the fiducial markings to each other and from the detected viewing position of the user 1 14. As can be seen in Fig. 9, the relative positions of the fiducial markings to each other will depend upon the relative position and orientation of the substrate 1 12 with respect to the camera 102. For example, when seen from a plan view 140, the relative positions of the fiducial markings to each other and to the camera 102 will have a first configuration whereas rotation of the substrate 1 12 about any one or more of the x, y and/or z axis will cause the relative positions of the fiducial markings to adopt a second configuration 142. Rotation of the substrate 1 12 about any one or more of the x, y and/or z axis can result, for example, from manipulation of the substrate 112 by the user.

[0056] In use, and as depicted in Fig. 10, the camera 102 initially captures an image of the surface of the substrate 1 12, at step 200. Next, at step 202, the data processing device 120 identifies the fiducial marking positions as well as, at step 204, the position of the viewer 1 14. From the relative positions of the fiducial markings to each other, and from the detected viewing position of the user 1 14, the data

processing device 120 then, at step 206, computes the relative position and

orientation of the substrate from the viewing position. The secondary memory 128 stores data characterising the security document intended to be manufactured and the, or each, security feature intended to be borne by the security document. The data processing device 120 computes the virtual representation of the security document and the, or each, security feature as it would be seen by the user 114 from the relative position and orientation of a substrate from that viewing position.

[0057] The data processing device 120 computes a virtual rotation about the x, y and/or z axis to be applied to a model of the security document and the or each security feature in order to compute the virtual representation as it would be seen by the user from their current viewing position. At step 206, a modification to the stored model is applied and then at step 210, an image is projected from a projector 212 coupled to the wireless communication device 1 16. [0058] As the user manipulates the substrate 1 12, causing the captured positions and relative orientations of the fiducial markings to change, steps 200 to 210 are repeated.

[0059] A variety of projectors are suitable for use in the system 100 shown in Figs. 7 and 8, including video projectors applying a technique called "projection mapping" to beamed images and animations onto surrounding objects.

[0060] Exemplary substrates are depicted in Figs. 4 to 6, and the suitability of each of these substrates will depend upon the material used for the manufacture of the substrate as well as the projection technology used in the projector 212. The substrate 220 depicted in Fig. 4 is a transparent or partially transparent substrate, and selection of appropriate materials for the substrate will enable an upper surface to be used for projection images.

[0061] The substrate 222 shown in Fig. 5, however, is an opaque substrate, or in the alternative is coated with one or more layers of opacifying material.

[0062] The substrate 224 shown in Fig. 6 is similarly covered in one or more layers of opacifying material. In the case of the substrate 222 however, a virtual window area is defined in the data stored in the secondary memory 128 of the data processing device 120 and the virtual representation of an optical effect in a corresponding window on a physical bank note or other security document is projected onto that virtual window area 226.

[0063] The substrate 224 though is partially opacified except in a transparent or partially transparent window region 228, and the virtual representation of an optical effect can then be projected into that window region 228 of the substrate 224.

[0064] Fig. 1 1 and 12 depict another embodiment of a system for generating a virtual representation of a security document. In this embodiment, system 250 includes the same elements as those depicted in Figs. 7 and 8 except that the projected 212 has been replaced by a virtual reality (VR) headset 252 that is used to display the virtual representation of the optical effect of the security features as it would be seen by the user from their current viewing position. [0065] For the sake of convenience, all elements in Figs. 1 1 and 12 that are identical to elements in Figs. 7 and 8 are marked with the same reference number as well as a prime superscript. For example, reference 1 12 in Figs. 7 and 8 has become reference 1 12' in Figs. 1 1 and 12.

[0066] The VR headset 252 is connected to the wireless communication device 1 18' by a corresponding wireless communication device 254. In this embodiment, images are displayed to the user via the VR headset, and need not be projected onto the surface of the substrate 1 12' manipulated by the user.

[0067] Fig. 13 depicts a variant of the embodiment shown in Figs. 1 1 and 12, whereby instead of the camera 102 acting as both the position sensing mechanism for the user's head and acting to capture fiducial markings on or within the substrate 1 12, a position sensing mechanism including a position sensor can be affixed directly or indirectly to the user's head. For example, the position sensor may form part of an Inertial Measurement Unit (IMU) 280. The IMU 280 is an electronic device that detects linear acceleration using one or more accelerometers and rotation rate using one or more gyroscopes. Data from the IMU 280 is supplied via the wireless communication device 254' and the wireless communication device 1 18" to the data processing unit 120, thereby avoiding the need to use the camera 102" to detect the position of the user's head.

[0068] As seen in Fig. 14, when in use, the system 200 shown in Figs. 1 1 and 12, as well as the variation shown in Fig. 13, perform a series of steps 290 to 298 corresponding to steps 200 to 208 performed by the system 100 shown in Figs. 7 to 9. A variation occurs in the final step shown in Fig. 14 though, where image projection is replaced by the step 300 of displaying the virtual representation of the security document and optical effects generated by the various security devices or features borne by the security document via the VR headset 252.

[0069] For the sake of convenience, all elements in Fig. 13 that are identical to elements in Figs. 7, 8, 1 1 and/or 12 are marked with the same reference number as well as two prime superscripts, for example, reference 130 in Fig. 8 has become 130" in Fig. 13. [0070] As can be appreciated from the above embodiments, the invention enables a user to handle a substrate, in the size and form of a security document, and view either directly on the substrate or by way of VR headset the final form of the security document. Importantly, optically variable devices and their effects are displayed virtually on the substrate and physical manipulation of the substrate is reflected in a true likeness of the optically variable effect of the optically variable devices in the virtual realm. Modifications to the design of the security document, such as colour or position changes, can be easily and quickly replicated within the system.

Modifications such as this, and particularly to the optically variable devices, can be made without the need to go to the time and expense of creating tooling and performing a industrial scale process.

[0071] Where any or all of the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification (including the claims) they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the presence of one or more other features, integers, steps or components.

[0072] It will be understood that the invention is not limited to the specific embodiments described herein which are provided by way of example only. The scope of the invention is as defined by the claims appended hereto.

Claims

The claims defining the invention are as follows

1. A method of generating a virtual representation of a security document, the security document having one or more security features, including: using a camera to capture fiducial markings on or within a substrate for physically representing the security document, the fiducial markings having a known correspondence to the extent of the substrate; using a position sensing mechanism to detect the viewing position of a user; from the relative positions of the fiducial markings to each other, and from the detected viewing position, using a data processing device to compute the relative position and orientation of the substrate from the viewing position; using a data storage device to store data characterising the security document and the or each security features; from the relative position and orientation of the substrate from the viewing position and from the stored data, using the data processing device to compute the virtual representation of the security document and the or each security feature as it would be seen by the user; and using an display mechanism to display the virtual representation of the security document as it would be seen by the user.

2. A method according to claim 1 , wherein the position sensing mechanism

includes the same or a different camera for capturing an image of the users head.

3. A method according to claim 1 , wherein the position sensing mechanism includes a position sensor directly or indirectly affixed to the user’s head.

4. A method according to claim 3, wherein the position sensor forms part of an Inertial Measurement Unit (IMU).

5. A method according to any one of the preceding claims, wherein the display mechanism includes a projector for projecting the virtual representation of the optical effect, as it would be seen by the user, onto the substrate.

6. A method according to claim 5, wherein the substrate is at least partially

transparent.

7. A method according to claim 5, wherein the substrate is opaque and the virtual representation of the optical effect is projected onto a virtual window area of the substrate.

8. A method according to claim 5, wherein the substrate is partially opacified

except in a transparent or partially transparent window region, and the virtual representation of the optical effect is projected onto the window region of the substrate.

9. A method according to any one of claims 1 to 4, wherein the display

mechanism includes a virtual headset for the displaying the virtual

representation of the optical effect as it would be seen by the user.

10. A method according to any one of the preceding claims, wherein fiducial

markings are on first surface of the substrate facing the user.

1 1. A method according to any one of claims 1 to 9, wherein the fiducial markings are on a second surface of the substrate facing away from the viewer, and substrate is at least partially transparent to light able to be detected by the camera.

12. A method according to any one of claims 1 to 9, wherein the fiducial markings are within the substrate, and substrate is at least partially transparent to light able to be detected by the camera.

13. A method according to any one of the preceding claims, wherein the or each security feature characterised by the stored data generates a micro-optical effect visible to the user.

14. A method according to claim 13, wherein the micro-optical effect is visible to the user when light is transmitted through the substrate to the user.

15. A method according to either one of claims 13 or 14, wherein the micro-optical effect is visible to the user when light is reflected from the substrate to the user.

16. A method according to any one of claims 13 to 15, wherein the micro-optical effect is not observable in visible light but is observable in infrared or ultraviolet light.

17. A method according to any one of claims 13 to 16, wherein the micro-optical effect is only visible to the user at particular relative angles of orientation between the security document and the user, notably due to obstructive or moire effects.

18. A method according to claim 13, wherein the stored data characterises an

optically variable device (OVD).

19. A system for generating a virtual representation of a security document, the security document having one or more security features, including: a camera to capture fiducial markings on or within a substrate for physically representing the security document, the fiducial markings having a known correspondence to the extent of the substrate; a position sensing mechanism to detect the viewing position of a user; a data processing device to compute the relative position and orientation of the substrate from the viewing position from the relative positions of the fiducial markings to each other, and from the detected viewing position; a data storage device to store data characterising the virtual representation of the security document and the or each security features, wherein the data processing device further computes the virtual representation of the security document and the or each security feature as it would be seen by the user from the relative position and orientation of the substrate from the viewing position; and a display mechanism to display the virtual representation of the security document as it would be seen by the user.

20. A system according to claim 19, wherein the position sensing mechanism includes the same or a different camera for capturing an image of the users head.

21. A system according to claim 19, wherein the position sensing mechanism includes a position sensor directly or indirectly affixed to the user’s head

22. A system according to claim 21 , wherein the position sensor forms part of an Inertial Measurement Unit (IMU).

23. A system according to any one of the claims 19 to 22, wherein the display mechanism includes a projector for projecting the virtual representation of the optical effect as it would be seen by the user onto the substrate.

24. A method according to claim 23, wherein the substrate is at least partially transparent.

25. A method according to claim 23, wherein the substrate is opaque and the virtual representation of the optical effect is projected onto a virtual window area of the substrate.

26. A method according to claim 23, wherein the substrate is partially opacified except in a transparent or partially transparent window region, and the virtual representation of the optical effect is projected onto the window region of the substrate.

27. A system according to any one of claims 19 to 22, wherein the display mechanism includes virtual headset for the displaying the virtual representation of the optical effect as it would be seen by the user.

28. A system according to any one of claims 19 to 27, wherein fiducial markings are on first surface of the substrate facing the user.

29. A system according to any one claims 19 to 27, wherein the fiducial markings are on a second surface of the substrate facing away from the viewer, and substrate is at least partially transparent to light able to be detected by the camera.

30. A system according to any one claims 19 to 27, wherein the fiducial markings are within the substrate, and substrate is at least partially transparent to light able to be detected by the camera.

31. A system according to any one of claims 19 to 30, wherein the or each security feature characterised by the stored data generates a micro-optical effect visible to the user.

32. A system according to claim 31 , wherein the micro-optical effect is visible to the user when light is transmitted through the substrate to the user.

33. A method according to either one of claims 31 or 32, wherein the micro-optical effect is visible to the user when light is reflected from the substrate to the user.

34. A method according to any one of claims 31 to 33, wherein the micro-optical effect is not observable in visible light but is observable in infrared or ultraviolet light.

35. A method according to any one of claims 31 to 34, wherein the micro-optical effect is only visible to the user at particular relative angles of orientation between the security document and the user, notably due to obstructive or moire effects.

36. A method according to claim 31 , wherein the stored data characterises an

optically variable device (OVD).