GB2600145A

GB2600145A - A device and method for measuring impact patterns

Info

Publication number: GB2600145A
Application number: GB2016825.8A
Authority: GB
Inventors: Geoffrey Swan Matthew; Livesey Richard; Davis Sally
Original assignee: UK Secretary of State for Defence
Current assignee: UK Secretary of State for Defence
Priority date: 2020-10-23
Filing date: 2020-10-23
Publication date: 2022-04-27
Also published as: GB202016825D0

Abstract

Measurement device 100 comprises an angle determination module 111, an image sensor 112, a digital image generation module 115, an image synthetisation module 114, measurement determination module (not shown) and a display module 113. Image sensor 112 captures a subject image of the surface impacted by an object. The digital image generation module 115 generates a digital image comprising two or more nested conic sections centred about a common origin and having respective boundaries. Said boundaries having an associated value of eccentricity corresponding to the angle between the impacted surface and the device. The image synthetisation module 114 synthesises the subject image with the digital image, and the measurement determination module determines the dimensions of the boundaries of the conic sections. The device 100 enables alignment of the conic sections with features of a surface impact pattern by adjusting the angle between the device 100 and the impacted surface. This allows measurement of surface patterns created by objects, such as projectiles, impacting a surface at non-perpendicular angles.

Description

A DEVICE AND METHOD FOR MEASURING IMPACT PATTERNS TECHNICAL FIELD

The invention relates to the field of measuring devices, in particular to measuring devices for measuring characteristics of impact patterns on surfaces impacted by objects and to methods of using said devices.

BACKGROUND

When an object impacts a surface that offers a degree of resistance to the kinetic energy of the object, the surface may deform, become eroded and/or have material deposited upon it. These deformations, erosions and/or deposits often result in an impact pattern formed from a series of peaks and troughs in the surface. Where the object has impacted the surface at a right angle to the plane of the surface the peaks and troughs of the impact pattern typically forms a series of concentric rings. The spacing and width of the rings generally relates to the mass characteristics along the longitudinal axis of the object.

Analysis of the dimensions and/or geometry of the impact ring pattern may provide information about the nature of the impacting object. This is especially the case for driven objects, such as, motorised objects, for example, Rocket Propelled Grenades (RPGs). Motorised objects often impact a surface at a predictable speed and therefore the resulting impact pattern may be largely considered a consequence of the mass characteristics along the longitudinal axis of the object. Analysis of the dimensions of the impact ring pattern, in particular the diameters of the rings, may be used to identify the object. For example, the dimensions of the impact pattern may be used to identify the object when compared with the dimensions of the known impact patterns of previously characterised objects.

However, when the object impacts the surface at an angle other than at a right angle to the plane of the surface, the impact pattern typically becomes distorted, and may, for example, form a group of nested conic sections, such as, circles, ellipses or parabola. Characterising the impacting object from this distorted impact pattern may be more complex and time consuming than for an object which impacted the surface at a right angle. For example, direct experimentation may be used to generate a reference dataset with which to characterise the distorted impact pattern of a known object for all possible impact angles. However, this may be costly, inconvenient and time consuming to generate. Alternatively, calculations to characterise the object from the distorted impact pattern, with reference to the known right angled impact pattern of an object, can be undertaken but these are often complex and time consuming especially in the absence of information regarding the angle of impact. Therefore, it may be advantageous to provide a new approach to measuring characteristics of an impact pattern on a surface.

SUMMARY

According to a first aspect of the invention there is provided, device for measuring characteristics of an impact pattern on a surface impacted by an object, the device comprising an angle determination module; an image sensor arranged to capture a subject image of at least part of the surface impacted by the object; a digital image generation module arranged to generate a digital image; wherein the digital image generation module is arranged to generate a digital image comprising two or more nested conic sections, the conic sections being centred about a common origin, each conic section having a boundary; an image synthetisation module arranged to generate a synthesised image by synthesising the subject image with the digital image; a display module arranged to display the synthesised image; and a measurement determination module arranged to determine the dimensions of the boundary of each conic section; wherein the boundary of each conic section has a value of eccentricity, and wherein the value of eccentricity corresponds to the angle between the impacted surface and the device and wherein, in use, each of the boundary of each conic section may be aligned with a feature of the impact pattern on the surface by selecting a diameter of the boundary and by adjusting the angle between device and the surface.

According to a second aspect of the invention there is provided, a method of measuring characteristics of an impact pattern on a surface impacted by an object, the method comprising the steps of: providing a device according to any of claims ito 6; receiving a subject image of at least part of the surface impacted by the object using the image sensor; determining the angle between the device and the surface using the angle determination module; generating a digital image using the digital image generation module wherein the digital image comprises two or more nested conic sections, the conic sections being centred about a common origin, each conic section having a boundary, the conic sections having a value of eccentricity which corresponds to the angle between the surface and the device; generating a synthesised image by synthesising the subject image with a digital image; displaying the synthesised image on the display module; aligning the boundary of each conic sections with a feature of the impact pattern on the surface by selecting a diameter of the boundary and by adjusting the angle between the longitudinal axis and the surface; determining the dimensions of the boundary of each conic section using the measurement determination module; and outputting the angle between the device and the surface and outputting the dimensions of each conic section.

The synthesised image combines the subject image comprising information about the impact pattern on the surface with the digital image comprising two or more nested conic sections. The synthesised image combines the digital image with the subject image such that the conic sections of the digital image may be aligned to overlay at least part of the impact pattern of the subject image.

The conic section form a nested group, whereby the conic sections may be circles, ellipses, parabola. The conic sections are nested about a common origin such that the values of eccentricity for each section are substantially equal. The digital image is generated such that the value of eccentricity corresponds to the angle between the impacted surface. For example, as the angle between the device and the surface changes, the values of eccentricity undergoes a corresponding change. For instance, when the angle between the device and the surface is substantially 90 degrees the value of eccentricity may be zero, such that the conic section is substantially circular. As the angle between the device and the surface decreases, the value of eccentricity may increase such that the conic section is, for example, either an ellipse or a parabola. For instance, the value of eccentricity may be zero when the angle between the device and the surface is 90 degrees may increase in a linear manner between zero and one as the angle between the device and the surface decreases.

The shape of the conic section may be similar or substantially similar to the shape of the features of the impact pattern when the angle between device and the surface matches, or substantially matches, the impact angle between the surface and the object. For example, the smaller the angle between the impacting object and the surface the more elongate the features of the impact pattern may be. Similarly, the smaller the angle between the device and the surface the more elongate the boundary of the conic section may be. By orientating the device such that the conic is section overlaid onto the subject image of the impact pattern is similar, or substantially similar, in shape to that of the features of the impact pattern it is possible to determine the impact angle of the object.

The angle between the surface and the device may be measured with respect to a longitudinal axis extending at 90 degrees from the plane of the image sensor.

The diameter of the boundary of each conic section is independently adjustable. The diameter of each conic section may be independently selected to overlay, or substantially overlay, a different feature of the impact pattern. When the boundaries of the conic sections are aligned with surface features of the impact pattern, the ratio of the diameters of the boundaries of the conic section is proportional, or substantially proportional, to the ratio of the diameters of the corresponding features of the impact pattern.

When the boundaries of the conic sections are aligned with two or more selected surface features, the angle between the device and the surface may match, or substantially match, the angle of impact between the object and the surface. When the boundaries of the conic sections are aligned with two or more selected surface features, the ratio of the diameters of the boundaries of the conic section may be proportional, or substantially proportional, to the ratio of the diameters of the corresponding features of the impact pattern. The device therefore provides a convenient means for determining the angle of impact from the angle between the surface and device and/or for determining the diameters, or relative diameters, of two or more features of the impact pattern from the diameters of the conical boundaries.

Information regarding the diameters, or relative diameters, between two or more features of a surface impact pattern and the angle of impact of the object may be particularly advantageous in characterising the nature of the object, for example, when characterising the longitudinal mass characteristics of an object. Driven objects, such as, those driven by a motor, often impact a surface at a predictable speed. The resulting impact pattern of a driven object may be largely considered a consequence of the mass characteristics along the longitudinal axis of the object. Such objects may include, for example, RPGs. RPGs typically have a characteristic mass profile along their longitudinal axis.

Analysis of the dimensions of the impact pattern, in particular, the actual diameters, and/or the relative diameters, of two or more features of the impact pattern, together with the angle of object impact, may be used to identify the object, for example, without the need to conduct multiple experimentations at differing angles or to perform overly complex calculations. For instance, measurements of the actual diameters, and/or the relative diameters, of two or more features of the impact pattern, together with the angle of object impact, may be used to identify an object with reference to an impact pattern of the object at a known impact angle, such as, 90 degrees. For instance, the invention may be particularly advantageous in identifying a particular type of RPG.

The image synthetisation module may comprise a processor.

The synthesised imaged augments the real world subject information of the impact pattern from the subject image with information from the digital image.

The subject image may be selected to update at regular intervals. For example, the subject image may be a sequence of images, such as, a video.

The image sensor may be any sensor suitable for capturing image information of the impact pattern. For example, the image sensor may be a charge-coupled device (CCD) or an active-pixel sensor.

The surface may be any type of surface that retains an impact pattern as a result of an impact by an object. For example, the surface may be masonry, or a metal, such as, steel or aluminium. The surface may be of any thickness sufficient to retain an impact pattern. The thickness of surface required to retain an impact pattern may vary dependant on the material from which the surface is formed.

The digital image generation module may comprise a processor configured to generate the conic sections.

The digital image may update in response to a change of angle between the device and the surface, such that, the values of eccentricity of the conic sections are updated to reflect a change in angle between the device and the surface. This may be particularly advantageous in providing a timely response in relation to changes of device orientation with respect to the surface.

The conic sections of the digital image may be arranged to be displayed in a pre-determined segment of the synthesised image, such as, the centre of the image. The field of view of the optical sensor may be positionable relative to the impact pattern, such that, the positioning of at least part of the selected features of the impact pattern of the subject image and the conic sections of the digital image are aligned within the synthesised image. This may provide a convenient means by which the conic sections may be aligned to overlay at least part of the impact pattern by positioning the device relative to the surface.

The boundaries of the conic sections of the digital image may be represented in any form suitable for alignment with features of the impact pattern when incorporated into the synthesised image. For instance, the boundaries may be represented using any suitable line type, such as, solid lines or broken lines. The boundaries may be represented as any suitable colour. The colour of the boundaries may be selected to produce the greatest contrast when overlaid onto the impact pattern. Each boundary may comprise the same form, such as, the same combination of colour and line type. Optionally, each boundary may be a different form, such as, a different colour and/or a different line type.

Optionally, the digital image may comprise a representation of the area of the conic sections. For instance, the area of the conic sections may comprise a colour or a pattern such as dots of hatchings. This may be advantageous in assisting the user to align the boundaries of the conic sections with features of the impact pattern.

The boundary of the conic section may be aligned with any suitable, selected features of the impact pattern. For example, suitable features may include protrusions, or peaks, and/or depressions, or troughs, on the surface. Peaks and troughs are both readily identifiable and therefore provide a convenient reference for alignment of the light pattern.

Optionally, the boundary of the conic section may be aligned with the innermost or the outermost edge of the impact feature. This may be particularly advantageous where the width of the feature is particularly large.

Optionally, the boundary of two conic sections may be aligned with the innermost and with the outermost edge of an impact feature. This may be particularly advantageous where the width of the feature is particularly large. This may be especially advantageous where it is desirable to determine the relative width of the feature from the dimensions of the conic sections.

Optionally, the digital image may comprise between 2 and 10 conic sections, or, more particularly, between 3 and 5 conic sections. For instance, the device may comprise 3 conic sections. The number of conic sections may be optimised for the specific application. For example, it may be more advantageous to have more conic sections when measuring more complex impact patterns, such as, those associated with objects having a greater degree of mass variation along the longitudinal axis.

In use, the boundary of each conic section may be adjusted to align with a selected feature of the impact pattern. For example, for a device comprising n conic sections, the diameters of the conic sections may be adjusted to align the first n features of the impact pattern. For instance, the first impact feature may be the innermost impact feature or the outermost impact feature.

The diameter of the conic sections may be adjustable between a maximum diameter and a minimum diameter. The maximum diameter and minimum diameter of a conic section may be optimised for a particular application.

The dimensions of the conic section may comprise the diameter and value of eccentricity.

Where the conic section is an ellipse or a parabola the diameter of the conic section may be selected to be the longest diameter.

Where the conic section is an ellipse or a parabola the diameter of the conic section may be selected to be the shortest diameter.

The diameters of the boundaries of the conic sections may be continuously adjustable. Being continuously adjustable may provide for greater precision in aligning the boundaries to an impact feature. Alternatively, the diameters of the boundaries may be adjustable in selected increments.

The measurement determination module may comprise a processor arranged to determine the dimensions of the boundary of each conic section.

The device may comprise an input module. The input module may be arranged to enable a user to input diameters of the boundaries of the conic sections into the digital image generation module. The input device may comprise any suitable interface means for example a microphone and speech recognition interface, a manual or a digital button(s) and/or a manual/digital dial(s).

The angle determination module may be arranged to determine an angle between the device and the surface. The angle determination module may comprise a sensor. The sensor may be any suitable sensor for measuring characteristics regarding the orientation of the device with respect to the surface. The angle determination module may comprise a processor for processing sensor information, for example to determine the angle between the surface. Optionally, the angle determination module may comprise an inclinometer. Optionally, the angle measurement unit may comprise a gyroscope. An inclinometer and/or a gyroscope may be particularly advantageous in determining the angle between the surface and the device.

For instance, when the orientation of the surface with respect to the direction of gravitation force is known.

Optionally, the angle determination module may comprise a movable arm. For instance, the movable arm may be movable with respect to the surface, or the device, or both the surface and the device.

Optionally, the movable arm may be attachable, or removably attachable, to the surface. The movable arm may be attachable to the surface by any suitable means, for example, by means of adhesive, hook and loop fastener(s), bolt(s), a negative pressure device, such as, e.g. suction cup, or any combination thereof. A movable arm which is attachable to the surface enables the device to be more easily held in position, relative to the surface. This may be advantageous in improving the precision of the measurements taken using the device.

Optionally, the movable arm may be connected at a first end in a fixed position to the device and pivotally connectable at a second end to the surface. Alternatively, the movable arm may be pivotally connected at a first end to the device and connectable at a second end in a fixed position relative to the surface.

Optionally, the movable arm may comprise a first portion and a second portion, where the first and second portions are pivotally connected to one another.

Optionally, the angle determination module may comprise a laser measure. A laser measure may be used to determine the distance between the device and the surface. The device may comprise two or more laser measures which may be arranged at known intervals about the device. For instance, the device may comprise two laser measures, for example, arranged on opposing edges of the device. The difference between the distances measured by the two laser measures may be used to determine the relative orientation of the device with respect to the surface and thereby determine the angle between the surface and the device.

Optionally, the device may comprise three laser measures which may be equidistantly spaced about the device. Three equidistantly spaced laser measures may be particularly advantageous where a good degree of confidence is required when measuring the angle between the device and the surface.

Optionally, the device may further comprise a distance determination module arranged to measure a distance between the device and the surface. Optionally, the distance between the device and the surface may be measured using the distance determination module and the distance between the device and the surface may be outputted.

For instance, the distance determination module may comprise a laser measure. The distance determination module may provide a convenient means for measuring the distance between the surface and the device.

Optionally, the distance between features of the impact pattern may be determined from the measured distance between the device and the surface and the measured diameter(s) and the value of eccentricity of the boundaries of the conic sections.

Optionally, the device may comprise a processor module, the processor module comprising an input from at least one of the measurement determination module, the angle determination module and the distance determination module. For instance, the processor unit may be arranged to determine the diameters of the impact features from the measured distance between the device and the surface and the measured diameters of the boundaries of the conic section.

The device may be arranged to output one or more measured values. For instance, the device may output one or more measured values, such as, the diameters of the boundaries of the conic sections, the relative diameters of the boundaries of the conic sections, the diameters of one or more impact features, the relative diameters of one or more impact features, the angle between the surface and the device, the values of eccentricity of the conic sections and the distance between the device and the surface. For example, the device may be arranged to output one or more measured values to a display and/or a processor. The display and/or processor may be integral to the device or remote from the device.

Optionally, the processor unit may be further arranged to identify the object by comparing one or more measured or determined features with corresponding features within a library of known object impact patterns. Such measured or determined features may include, the measured angle of impact, the determined angle between the device and the surface, the measured diameters of one or more features of the impact pattern, the determined diameters of the boundaries of the conic sections, the value of eccentricity of the conic sections, the relative diameters of the boundaries of the conic sections, the distance between the device and the surface.

For example, the processor unit may be arranged to identify the object by comparing the measured angle of impact and the relative diameters of the spacing between the boundaries of the conic sections when aligned with two or more selected features of the impact pattern with the corresponding angle of impact and relative spacing of two or more features of the impact pattern of a known object.

Optionally, the device may be arranged to identify the object when the relative spacing between the boundaries of two or more conic sections and the angle between the device and the surface when the conic sections are aligned with two or more features of the impact pattern matches or substantially matches a known angle of impact and known relative spacing of two or more features of the impact pattern of a known object.

Optionally, the device may be arranged to identify the object when the measured diameters of two or more features of the impact pattern and the angle between the device and the surface when the conic sections are aligned with two or more features of the impact pattern matches or substantially matches a known angle of impact and known diameters of two or more features of the impact pattern of a known object.

Identifying the object may comprise identifying a particular model of object, such as, a specific RPG model. Identifying the object may comprise identifying a class of object, such as, a group of objects sharing common mass characteristics.

The relative diameters of the spacing between the boundaries of the conic section and/or the relative spacing of the features of the impact pattern may be expressed as a ratio or a percentage value.

Advantageously, the digital image generation module may be arranged to select the diameter of the boundaries of the conic sections so as to produce a nested set of conic section having the relative spacing of the impact pattern produced by known object(s) of interest. Such object of interest may be for example RPGs.

Optionally, the diameter of the boundaries of one or more of the conic sections may be selected from a library. The digital image generation module may be arranged so as to adjust the boundaries of the conic sections by selecting pre-determined template from a library. The library may comprise two or more templates. Each template may specify a predetermined diameter of the conic sections, which produce a set of nested conic sections having a spacing corresponding to the impact pattern of a known object. For example, a user of the device may be able to select a particular template. Optionally, the digital image generation module may be arranged to cycle through a library of templates until the set of nested conic sections matches or substantially matches selected features of the impact pattern on the surface. This may be particularly advantageous when identifying the impact pattern from a known class of objects, such as, RPGs.

Optionally, the display module may be further arranged to display one or more of the angle between the device and the surface the dimensions of the boundary of each conic section and the distance between the device and the surface. This may be particularly convenient in enabling determined characteristics to be made rapidly available to the end user.

BRIEF DESCRIPTION OF DRAWINGS

The invention will be described in more detail by way of example with reference to the accompanying drawings, in which: Figure 1 shows a cross sectional representation of a device, according to an embodiment of a first aspect of the invention.

Figure 2 shows a side view representation of the device of Figure 1 in use Figure 3a shows a representation of a digital image, according to an embodiment of a second aspect of the invention.

Figure 3b shows a representation of a subject image, according to an embodiment of a second aspect of the invention.

Figure 4 shows a representation of the generation of a synthesised image, according to the embodiment of figure 3a and 3b.

Figure 5 shows a flow diagram of a method according to a second aspect of the invention.

The drawings are for illustrative purposes only and are not to scale.

DETAILED DESCRIPTION

Figure 1 shows an illustration of a first embodiment of the first aspect of the invention. A device 100, having an angle determination module 111, an image sensor 112, a digital image generation module 115, an image synthetisation module 114 and a display module 113 is shown.

The angle determination module 111 incorporates an inclinometer. The inclinometer is arranged to measure the angle between the device 100 and a surface impacted by an object with respect to the direction of gravity. The device 100 is configured to measure the angle between the surface and the device 100 when the orientation of the surface with respect to the direction of gravity is known.

The angle determination module 111 further comprises a processor and is configured to determine the angle between the device and a surface. The angle determination module is connected to the digital image generation module 115 via cable 116. The angle determination module 111 is arranged to output the angle between the device and the surface to the digital image generation module 115. The digital image generation module 115 comprises a processor unit and is configured to generate a digital image. The digital image generation module 115 is connected to the image synthetisation module 114 via cable 118.

The image sensor 112 is a charged coupled device (CCD). The CCD 112 is arranged to capture a digital image of at least part of the impact pattern on the surface. The CCD 112 is arranged to output a subject image to the image synthetisation module 114. The CCD 112 is connected to the image synthetisation module 114 via cable 117.

The image synthetisation module 114 comprises a processor which is configured to generate a synthesised image from a digital image received from the digital image generation module 115 and a subject image received from the CCD 112.

The image synthetisation module 114 is connected to the display module 113 via cable 119. The image synthetisation module 114 is arranged to output a synthesised image to the display module 113. The display module 113 is a flat panel Liquid Crystal Display (LCD). The LCD 113 is arranged to display the synthesised image to a user.

Figures 2 shows an illustration of the first embodiment of the first aspect of the invention when in use. The device 100, is shown with the CCD 112 orientated in the direction of surface 120. Surface 120 has an impact pattern 121 formed by an object (not shown) which impacted the surface 120 at 90 degrees to the plane of the surface. The impact pattern 121 has three concentric circular features 122, 123, 124 which are raised regions on the surface. The angle 125 between the surface 120 and the device 110 is measured with respect to a longitudinal axis 126 extending at 90 degrees from the CCD 112, corresponding to the angle of impact of the object.

With reference to figures 3a, 3b, 4 and 5, in an embodiment of the second aspect of the invention, a device 100 for measuring the impact pattern 121 on a surface 120 impacted by an object is provided 501 according to the first aspect embodiment shown in figures 1 and 2.

The CCD 112 is oriented towards the surface 120 comprising an impact pattern 121. The CCD 112 receives 502 a subject image 300 (figure 3b) comprising image information of three concentric circular features 122, 123, 124 of impact pattern 121 on the surface 120. The subject image 300 is outputted to the image synthetisation module 114.

The angle 125 between the device 100 and the surface 120 is determined using the angle determination module 111 using the orientation of the gyroscopes and a known orientation of the surface 120 with respect to gravity. The angle 125 is outputted to the digital image generation module 115.

The digital image generation module 115 generates 504 a digital image 200 (figure 3a). The digital image comprise two nested conic sections 201, 202. The conic sections are centred about a common origin 205. Each conic section has a boundary 203, 204. The conic sections 201, 202 have a value of eccentricity which corresponds to the angle 125 between the surface 120 and the device 100. The relationship between the value of eccentricity and angle between the device and the surface 125 is such that the value of eccentricity is zero when the angle between the device and the surface is 90 degrees and increases in a linear manner between zero and one as the angle 125 decreases. The boundaries 203, 104 of the digital image 200 are represented as continuous black lines. The digital image 200 is outputted to the image synthetisation module 114.

The image synthetisation module 114 generates 505 a synthesised image 400 (figure 4) by combining the image information of the subject image 300 with the image information of the digital image 300. The synthesised image 400 comprises the three concentric circular features 122, 123, 124 of impact pattern 121 from the subject image 300 augmented by the two conic section 201, 202 of the digital image 200.

The image synthetisation module 114 is configured to generate the synthesised image 400 such that the common origin 205 of the conic sections 201, 202 of digital image 200 are centred in the synthesised image.

The image synthetisation module 114 outputs the synthesised image 400 to the LCD display 113. The LCD display 113 displays 506 the synthesised image 400.

In the synthesised image of Figure 4, the diameters of the conic sections 201 and 202 have been selected, and the orientation of the device 100 has adjusted, such that the boundaries 203, 204 of the conic sections 201, 202 are aligned 507 with the outer edge of features 122, 123 of impact pattern 121. In particular, the angle 125 between the device 100 and the surface 120 is 90 degrees. This matches the angle between the object and the surface on impact. The value of eccentricity for the digital image of Figure 3a is zero, such that the conic sections 201,202 are circular.

The processor of the digital image generation module 115, outputs the shortest diameter and the value of eccentricity of the boundaries 203, 204 of conic sections 201, 202 to LCD display 113 via the image synthetisation module 114.

The angle determination unit outputs the angle 125 to the LCD display 113 via the digital image generation module 115 and the image synthetisation module 114.

The LCD display 113 displays 509 the angle 125 and the diameter and the value of eccentricity of the boundaries 203, 204 of conic sections 201, 202.

Claims

CLAIMS1 A device for measuring characteristics of an impact pattern on a surface impacted by an object, the device comprising an angle determination module; an image sensor arranged to capture a subject image of at least part of the surface impacted by the object; a digital image generation module arranged to generate a digital image; wherein the digital image generation module is arranged to generate a digital image comprising two or more nested conic sections, the conic sections being centred about a common origin, each conic section having a boundary; an image synthefisation module arranged to generate a synthesised image by synthesising the subject image with the digital image; a display module arranged to display the synthesised image; and a measurement determination module arranged to determine the dimensions of the boundary of each conic section; wherein the boundary of each conic section has a value of eccentricity, and wherein the value of eccentricity corresponds to the angle between the impacted surface and the device and wherein, in use, each of the boundary of each conic section may be aligned with a feature of the impact pattern on the surface by selecting a diameter of the boundary and by adjusting the angle between device and the surface.The device of claim 1, wherein the angle determination module comprises an inclinometer The device of any preceding claim wherein the angle determination module comprises a gyroscope The device of any preceding claim, wherein the angle determination module comprises a laser measure.The device of any preceding claim, further comprising a distance determination module arranged to measure a distance between the device and the surface.The device of any preceding claim wherein the display module is further arranged to display one or more of the angle between the device and the surface, the dimensions of the boundary of each conic section and the distance between the device and the surface.A method of measuring characteristics of an impact pattern on a surface impacted by an object, the method comprising the steps of: providing a device according to any of claims 1 to 6; receiving a subject image of at least part of the surface impacted by the object using the image sensor; determining the angle between the device and the surface using the angle determination module; generating a digital image using the digital image generation module wherein the digital image comprises two or more nested conic sections, the conic sections being centred about a common origin, each conic section having a boundary, the conic sections having a value of eccentricity which corresponds to the angle between the surface and the device; generating a synthesised image by synthesising the subject image with a digital image; displaying the synthesised image on the display module; aligning the boundary of each conic sections with a feature of the impact pattern on the surface by selecting a diameter of the boundary and by adjusting the angle between the longitudinal axis and the surface; determining the dimensions of the boundary of each conic section using the measurement determination module; and outputting the angle between the device and the surface and outputting the dimensions of each conic section.The method of claim 7 wherein the diameter of the boundaries of one or more of the conic sections are selected from a library.The method of any of claims 7 and 8 wherein the method further comprises the steps measuring the distance between the device and the surface using the distance measurement unit and outputting the distance between the device and the surface.