GB2508617A - Terrain-topography motion capture system, apparatus and method - Google Patents

Abstract

A terrain-topography motion capture system 10 comprises an inertial measurement element 12 which is mountable on a user or user's equipment at a location having a determinable distance relative to a user-terrain contact point and which is able to determine a position, motion and attitude of the user and/or equipment; a stabilisation element 14 for preventing or limiting integration drift of inertial measurement data; a data storage element 18 for storing the inertial measurement data; a data processing unit 20 including a data inverter 74 for inverting stabilised inertial measurement data to determine terrain-topography point data, and a terrain-model generator for generating a three-dimensional terrain model of a travelled path based on consecutive said terrain-topography point data; and a display 22 for outputting the three-dimensional terrain model. The model generator may enable extrapolation of the terrain-topography point data to terrain-topography path data or the use of satellite imagery in the model.

Description

Terrain-Topography Motion Capture System, Apparatus And Method The present invention relates to a telTain-topography motion capture system which is able to capture user motion data along a terrain and generate a three-dimensional terrain model therefrom, preferably but not necessarily exclusively including a three-dimensional animated user model. The invendon also includes apparatus which is preferably wearable by the user and/or mountable on the user's equipment to capture the motion, and also a method of generating a terrain mod& using such a terrain-topography motion capture system.

Optical image recording devices for sportspeople, professional, amateur andlor recreational, are now well known and affordable. Such devices are available from a range of companies, such as GoPro RTM and GoBandit RTM. These companies provide video recording devices which are rugged and mountable to a user and/or their equipment. The video of the user performing his or her discipline, for example, mountain biking, skiing, snowboarding, surfing or windsurfing can thus be captured.

Some devices are able to geo-tag the imagery via an integrated GPS unit, thus allowing the user after the event to view the captured video along with seeing a birds -eye view of the route that they had travelled, for example, via importing into Google Earth RTM or similar.

Pure motion capture systems are also known, and many of these rdate to instruction or training, for example, to improve a user's golf swing. Typically, a known motion capture system may use a video camera or a plurality of body mountable sensors to capture the motion of the user's whole body. This can then be analysed against a professional athlete, and the differences in body movement displayed to the user, thereby allowing correction.

The problem with optical image recording devices is that only one viewpoint can be provided, uffless multiple cameras are utilised. However, a multi-camera option dramatically increases weight and expense and therefore is generally discounted. A third party could be utilised with an independent camera to provide a different viewpoint, but again this involves the use of another person, which can be problematic if not available or if not able to move faster than the athlete being monitored so that the entire terrain travelled can be monitored.

Furthermore, optical image recording devices do not permit the terrain to be modefled from data collected as the athlete travels across the terrain. Video recorders mounted to the user and/or their equipment do not typically allow the interaction between the user and/or their equipment with the terrain to be monitored and analysed. This makes it difficult therefore to compare event performances of a particubr user and/or between different athletes.

Additionally, video cameras generate a significant amount of footage which then has to be edited to find the highlights. This is time consuming.

Known motion capture systems as mentioned above are problematic in that they are usually not portable or mobile, thereby preventing or limiting a user wearing the system outside. If a user mountable sensor array is utilised. this is usua'ly large in order to provide for mounting on all major joints of limbs, torso, head and distal portions of appendages. Such a number of sensors is cumbersome and prone to damage, and furthermore will only monitor the athlete and not the interaction with the terrain being travelled.

The present invention therefore seeks to provide a solution to these problems, by in the first instance providing a system which is capable of modelling travelled terrain via motion capture of the user and/or the user's equipment.

According to a first aspect of the invention, there is provided a terrain-topography motion capture system comprising an inertial measurement element which is mountable on a user or user's equipment at a location having a determinable distance relative to a user/terrain contact point and which is able to determine a position, motion and attitude of the user and/or equipment; a stabilisation element for preventing or limiting integration drift of inertial measurement data of the inertia' measurement element; a data storage element for storing the inerial measurement data; a data processing unit including a data inverter for inverting stabilised inertial measurement data to detemñne terrain-topography point data, and a terrain-model generator for generating a three- dimensional terrain modd of a travelled path based on consecutive said terrain-topography point data; and a display for outputting the generated three-dimensional terrain model.

Preferable and/or optional features of the first aspect of the invention are set forth in claims 2 to 25, inclusive.

According to a second aspect of the invention, there is provided telTain-topography motion capture apparatus for use with a terrain-topography motion capture system according to the first aspect of the invention, the apparatus comprising a housing which is removably mountable to a user and/or a user's equipment, and the inertial measurement element and stabilisation element within the housing.

Preferably, the terrain-topography motion capture apparatus, further comprises the data storage element, the data processing unit, the terrain-model generator, and/or the display on or in the housing.

According to a third aspect of the invention, there is provided a method of generating a three-dimensional telTain model using a terrain-topography motion capture system in accordance with the first aspect of the invention, the method comprising the steps of: a] determining position, motion and attitude of a user and/or a user's equipment from stabilised inertial measurement data derived from a user moving along telTarn; b] inverting the stabilised inertial measurement data; and c] generating and displaying a three-dimensional terrain model derived from the inverted stabilised inertial measurement data.

Preferable and/or optiona' features of the third aspect of the invention are set forth in claims 30 to 33, inclusive.

The invention will now be more particularly described, by way of examples only, with reference to the accompanying drawings, in which: Figure 1 is a block diagram of one embodiment of a terrain-topography motion capture system. in accordance with the first aspect of the invention; Figure 2 is a plan view of a PCB and associated circuitry forming a first example of a data capture unit of the terrain-topography motion capture system of Figure 1; Figure 3 is a side elevational view of a user and his equipment moving across terrain to be modelled, and showing possible mounting points for the data capture unit; Figure 4 is a view similar to Figure 3, but this time showing a reladonship between the data capture unit and the terrain, as the angle of the terrain alters; Figure 5 is a flowchart providing indicative processing steps once position, motion and attitude data have been acquired by the data capture unit; Figure 6 is an example of a pit-rendered terrain modd formed by a terrain-model generator of the system from position, motion and attitude data acquired by the data capture unit; and Figure 7 is a view of a post-rendered terrain model, and showing a three-dimensional terrain model and animated sportsperson.

Referring to the drawings. there is shown a one embodiment of a teiTain-topography motion capture system 10 which comprises an inertial measurement element 12, a stabilisation element 14, a time-stamping circuit 16, a data storage element 18, a data processing unit 20, and a display 22. In this case, the system 10 is divided into two separate units which are in data communication with each other, for example, wirelessly utilising Bluetooth RTM or another suitable wireless data transfer protocol. Hard-wired communication can a'so be considered.

The first unit is preferably a data capture unit 24 including the inertial measurement element 12, at least part of the stabilisation element 14 and the time-stamping circuit 16, and the second unit is preferably a data manipulation unit 26 which includes another part of the stabilisation element 14, if necessary, along with the data storage element I 8.

data processing unit 20, and the display 22.

Although separated into a discrete data capture unit 24 and a discrete data manipulation unit 26, the system 10 may be realised as a single unit, or may be comprised of more than two units, for example, by having a separate independent display 22.

Although one display 22 is suggested, utilisation of more than one display may be possible. For example, a small-screen onboard display may be provided as part of the data manipulation unit 26, along with a data output which provides communication options with a remote display, such as a user's larger-screen television andlor computer monitor.

The data capture unit 24 includes a mountable housing 28 which is mountable on a user or user's equipment 32 at a location which is at least a substantially constant distance relative to a user/terrain contact point 34. As shown in Figure 3, a suitable mounting point preferably needs to have predictable dynamic behaviour and ideally not one which is subjected to frequent erratic brge ranges of movement relative to the terrain surface being followed. Consequently. suitable locations would be by way of example: an athlete's head or helmet 36; torso, waist or clothing/accessories associated therewith, such as a rucksack or backpack 38, jacket or jersey pocket, or belt; and/or the athlete's equipment 32 which in this embodiment may be a mountain bike and as such affords mounting options on a seat post 40, handle bars 42 and/or front triangle 44 of a frame.

Mounting could also take place on suspension components, since these components do have predictable dynamic behaviour which can be accounted for in the data processing algorithms, discussed herebelow.

The mountable housing 28 may be a simple plastics or metal weatherproof and preferably shock-resistant enclosure, and including a mounting element for releasable attachment to the elements described above. The mounting element may conveniently be a relatively thick elastomeric or rubber band. Such a mounting element is already known for attaching cycle lights and the like, and therefore further detailed description is omitted.

As shown in Figure 2, the mountable housing 28 preferably houses a PCB 46 on which is provided the inertial measurement element 12, a first stabilisation device 48 of the stabilisation element 14, and a data-capture microprocessor 50, for example. based on an ARM Cortex-MO and which amongst other things controls time stamping of inertial measurement data and stabilisation data. A captured-data storage device 52, such as RAM, flash program storage device 54 and input/output circuitry 56 may also be provided, along with a wireless data transmitter 58. The processing required in the data capture unit 24 is typically limited to accurate acquisition of the inertial navigation data and stabilisation data to prevent or limit integration drift, along with buffering for transmission to the data manipulation unit 26.

The PCB 46 may only require a length of approximately 50 mm. and a width and height of approximately 20 mm. As such, the mountable housing 28 can be produced with compact dimensions, facilitating simple, convenient and unobtrusive mounting.

The inertial measurement element 12 on the PCB 46 is preferaNy a single MEMS module incorporating together a three-axis accelerometer 60 and a three-axis gyroscope 62. Conveniently, such a device is an LSM33ODLC from ST Microelectronics at www.st.com.

The first stabilisation device 48 on the PCB 46 and co-located in close proximity to the inertial measurement element 12 in this case is a three-axis magnetometer 64, such as a 1-1MC5883L from 1-loneywell at www.honeywell.com. and aho referred to as a three-axis digital compass.

Other forms of accelerometer, gyroscope andior magnetometer may be considered, as required.

The processing power of the separate data manipulation unit 26 is typically greater and used for a majority of the data processing and terrain modelling requirements. If the system 10 is provided as a sing'e device, however, then a more powerful processor than that suggested above would be required in order to be able to complete the inertial navigation and the terrain generation algorithms, along with sufficient memory to buffer the inertial navigation data. stabilisation data and any other data required. should the processor not be able to perform the processing in real time.

The data manipulation unit 26 includes the data storage element 18, data processing unit 20, and an integrated display 22, as described above. In this case, the data manipulation unit 26 may beneficially be a mobile computing device, such as a mobile telecommunications device 66, for example, a so-called smartphone'. For example, an Apple iphone RTM or Samsung Galaxy S3 RTM has sufficient data processing power to be useable as the data manipulation unit 26.

Additionally, the data manipulation unit 26 in this case also preferably includes the other part of the stabilisation element 14. Although not essential, a second stabilisation device 68 to provide supplementary or auxiliary stabilisation data is provided and forms the other part of the stabilisation element 14. The second stabilisation device 68 is advantageous in providing improved accuracy to the inertial navigation data generated by thc incrtial mcasurcmcnt dcmcnt 12, and in this cmbodirncnt is prcfcrably a gthbal positioning system [GPS] device which is typically incorporated as part of the mobile telecommunications device 66 during manufacture.

The data manipulation unit 26 includes a wireless data receiver 70 which is communicable with the wireless data transmitter 58 of the data capture unit 24. In this way. the data manipulation unit 26 can be carried by the user 30 about their person. for example, in a pocket or rucksack, and can receive inertial measurement data and first stabilisation data, either in real time or buffered, from the data capture unit 24. The inertial measurement data and the first stabilisation data of the first stabilisation device 48 are preferably time stamped to enable data correlation during processing within the data manipulation unit 26. Additionally, the second stabilisation data outputted by the second stabilisation device 68 is also time stamped to enable corrdation with the inertial measurement data and the first stabilisation data. The time stamping is preferable, since it is expected that the various data streams may be sampled at different rates, thus requiring time stamping to aid accurate correlation.

The first and second stabilisation data are utilised to stabilise the inertial measurement data, which is typically inertial navigation data, thereby preventing or limiting undesirable integration drift. This occurs preferably within the data manipulation unit 26, but could occur within the data capture unit 24, whereby pre-stabilised inertial measurement data may be outputted to the data manipulation unit 26 for supplementary stabilisation and/or further processing.

Although the second stabilisation device 68 is preferred and will provide improved stabilised inertial measurement data, it is not necessarily essential and can therefore be dispensed with.

The stabilised inertial measurement data is then inputted to one or more inertial navigation algorithms 72 of the data processing unit 20, effectively forming a data inverter module 74 which produces an estimate of the position, motion and attitude of the inertial measurement element 12 which is then outputted to an inverse data model 76 of the athlete's and/or athlete's equipment body. As can be understood from Figure 4, a profilc of thc terrain can bc dcrivcd tiom a position of thc inertial mcasurcmcnt element 12 and velocity for a specific application, in this case being mountain biking.

The velocity of the inertial measurement element 12 provides an angle of motion. A relationship between a location of the inertial measurement element 12 and a contact point 34 where the back wheel 78 of the mountain bike 80 touches the ground is defined either using a static approximation or by using dynamics of the rider to estimate changes. This is shown as the triangle marked X, and this triangle X is then rotated according to a direction of the velocity vector V to provide an adjusted mapping from the inertial measurement element 12 to the terrain 82 being travelled at that time. The data inverter module 74 generates an equivalent data set which is generally an inversion of the stabilised inertial measurement data and which thus equates to the point P where the athlete or the athlete's equipment 32 touches the supporting surface, typically but not necessarily exclusively at all times being the ground.

The acceleration analysis uses an output from the data inverter module 74 to translate raw acceleration inputs into acceleration in key directions, and then performs specific analysis on the key directions to determine terrain-topography point data T at a given time point. The terrain-topography point data T relates to the texture or topography of the terrain and details regarding how the athlete and/or their equipment is moving across that terrain.

The terrain-topography point data T is then outputted to a terrain-model generator module 84 of the data processing unit 20. This may be in the form of a third-party data software application instailable on the mobile telecommunications device 66, as required. The terrain-model generator module 84 generates a three-dimensional terrain model 86 of a travelled path based on consecutive terrain-topography point data T at a plurality of time points. The terrain-model generator module 84 preferably extrapolates the terrain-topography point data T laterally to determine terrain-topography path data W approximating to a width of a path travelled. For example, an initial wire-frame model 88 of the terrain may be formed with smaller triangles 90 being closer to the terrain-topography point data T and increasingly larger triangles 92 being used as extrapolation occurs away from the recorded user/ground contact point 34. See Figure 6.

The data processing unit 20 preferably further includes a user-model generator module 94 which generates a three-dimensional animated user model 96 to be included with the terrain model 86 generated by the terrain-model generator module 84. See Figure 7.

Animated user motion of the animated user model 96 is based on the inertial measurement data of the inertia' measurement element 12. stabilisation data of the stabilisation dement 14, and preferably the activity being undertaken. The time stamping of the inertial measurement data and the stabflisation data therefore enaNes the animated user model 96 to be located at specific points along the terrain model 86.

The data processing unit 20 also includes a key-event detector element 98 which is able to determine key-event points lOG based on position, motion and/or attitude derived IS from the inertial measurement data. See Figure 7. Together with acceleration analysis.

one or more key events along the terrain travelled by the athlete can be determined and viewed via the display 22. Since these are likely to be of interest to the user 30, these determinable points 100 can be outputted as markers 102 to the modelled terrain, allowing a user 30 to skip to these positions on the recorded route. By way of example, key events may be very steep sections of terrain and/or jumps, such as a longest and/or highest jump, where the athlete and/or the athlete's equipment are airborne.

To provide base-data sets for the data manipulation unit 26 to operate from, it is preferable that at least one or more of a terrain selector 104, an environment selector 106, and an activity selector 108 is provided. These may be independent of each other, or combined as required.

The terrain selector 104 preferably provides for the selection of a terrain type from amongst a plurality of different terrain types, with a predefined base terrain-data set relating to the selected terrain type then being outputted to the data processing unit 20 for use by the terrain-model generator module 84 in conjunction with the inverted stabilised inertial measurement data. By way of example, the user 30 dunng the setup in preparation for recording their activity may select the type of terrain as being flat or steep, which then provides the data manipulation unit 26 with a base reference allowing querying if data dramatically outside of the base reference is generated.

The environment selector 106 allows the selection of an environment type from amongst a plurality of different environment types. Once selected, a predefined base environment-data set relating to the selected environment type is outputted to the data processing unit 20 for use by the terrain-model generator module 84. By way of example, the user 30 during preparation for recording their activity may select the type of environment as being heavily wooded, lightly wooded, narrow singletrack, wide path, rocky, iooty, muddy, thy. powder snow, hard packed snow, on-piste, off-piste, manmade stadium athletic track. velodrome, cana' path. and such like. Environment data representative of each of these activities can thus be predetermined and pre-stored ready for selection by the user 30. It is also feasible that multiple combinations of different representative environment data can be selected. If the captured stabilised inertial measurement data therefore departs significantly from the base reference data, this can be queried and either automatically and/or manually corrected if required.

It is beneficial that the environment selector 106 makes use of environment data input which is at least in part remotely receivable from a third party data source. In this case, the third party data source may advantageously provide geographic information system [GIS] mapping data. By way of example, GIS mapping data can be obtained from Google RTM via the internet. The telTain-model generator module 84 may access this data using an internet connection based on the inertial measurement data, stabilisation data, and environment type selected by the user 30. Appropriate image data, either downloaded or pre-uploaded to the data manipulation unit 26, can thus be utilised by the telTain-model generator module 84 to complete the telTain model 86 and provide a more realistic environment.

Additionally or alternatively, the environment selector 106 may be automated via an optical image recorder 110, for example, forming part of the data manipulation unit 26.

It is conmion to provide an image recorder 110 as part of a mobile telecommunications device 66. The environment type may thus be determined via the image recorder 110, and/or environment data captured by the image recorder 110 during performance of the activity may then be utilised by the terrain-model generator modu'e 84 during generation of the terrain model 86.

In this case, the image recorder 110 should be mountable on the user 30 and/or the user's equipment 32 at a suitable location for recording to take place. As an addition or alternative, it may be convenient to include an optical image recorder I iOa, preferably having a wide-angle lens of approximately 135 degrees or more, as part of the data capture unit 24.

The activity selector 108, as with the telTain selector 104 and environment selector 106, is preferably accessible from the display 22, which in this case may be a touch-or pressure-sensitive display enabling user input thereby. The activity selector 108 enables pre-selection of an activity type from amongst a plurality of different activity types, which then provides a predefined base activity-data set for use by the data inverter module 74 during determination of the key directions and also subsequently the user-model generator 94 utilising the predefined base activity-data set when generating the IS animated user model 96. By way of example, the activity selector 108 may provide options for downhill mountain biking, cross-country mountain biking, road cycling, indoor pursuit cycling, freestyle skiing/snowboarding, on-piste skiing/snowboarding, off-piste slciing/snowboarding, surfing, windsurfing, jogging, stadium track events, and such like.

It may also be beneficia' to provide an equipment sdector, for example, as part of the activity selector 108, which enables a user 30 to select their specific or generic equipment being used. This then provides a predefined base equipment-data set for use by the user-model generator module 94.

It is further possible that photo-realistic images of the athlete and/or the associated equipment and clothing may be taken and uploaded to the data manipulation unit 26 for incorporation by the user-model generator module 94.

The above-described elements are combinable to provide a three-dimensional model of the whole or part of the terrain travelled, a three-dimensional model of the sports motion along the terrain, and a set of highlights of the performance. The viewpoint of the animation as seen via the display 22 can preferably be altered during or before playback to be third-person or first-person. Different third-person viewing an&es may also be accommodated, either being set before playback or being dynamically alterable during playback.

It is also possible to provide additional performance data of the athletic performance, denved from the inertial measurement data. By monitoring the acceleration along the terrain, the power outputted by the athlete can be estimated from the magnitude of the acceleration in a particular direction. A minimum acceleration would correspond to the user slowing down due to resistance, and the acceleration above this level equating to the actual effort put in by the user.

Although it is preferable to provide a time-stamping circuit to time stamp the inertial measurement data and the stabilisation data, it is possible that improvements in accuracy andlor further integration of the inertial measurement element and the stabilisation element may dispense with the need for time stamping. When generating IS the terrain model, it is not an essential requirement that time points are required, as long as the inverted stabilised inertial measurement data can be ordered.

Furthermore, it is beneficial to have time stamping of data when intending to provide a three-dimensional animated user model moving on the generated terrain model.

However, if the user model is omitted and only the terrain model is generated, then again the time-stamping circuit may not be necessary.

It is preferable that the terrain-topography motion capture system is powered by one or more rechargeable battery packs, either located onboard or remotely. However, other power sources or combinations thereof may be utilised. For example, a separate data processing unit and/or dispby may be mains powered.

Additionally, the data storage dement and/or the data processing unit may be remote from the user. For example, the data capture unit may output its data to a remote data processing unit, such as a user's computer after the performance of the event. The data processing thus occurs on the user's computer, before being outputted to a display of choice. Consequently, although the terrain-topography motion capture system of the invention may be entirely carried by the athlete, either as two units as described above or even as one unit, only the data capture unit may be carried with the data manipulation unit being remotely located.

Thc invcrsc modcl of thc sportspcrson's body and thcir cquipmcnt, to gcncratc an estimate of the motion of the point where they touch the ground will translate the estimate of motion of the inertial sensors to the actual track along the ground, based at least on the height that the sensor is mounted above the ground and the angle at which the sportsperson is eaning at that point. The model may also depend on the type of motion, for example, walking, running or cycling, and a different model used as appropriate. Depending on the required accuracy, the model may be further refined to include the dynamics of the movement, such as the shock absorption of the sportspcrson's lcgs or thc suspcnsion of thc bikc. For applications whcrc thc athlctc is on foot, the detection of the points where the foot touches the ground will be used as the sample points on the terrain, with the acc&eration data used to detect when the body is directly over the foot.

Analysis of the acceleration data, including but not limited to frequency analysis of the acceleration along the track and in the vertical direction, enables translation according to the attitude estimate from the inertial measurement dement. This provides acceleration along the track and acceleration on a vertical axis. Frequency domain analysis is then performed on these accelerations independently, to extract additional information.

For the vertical axis accelerations, the frequency and magnitude of the signals relative to the speed along the track is used to estimate the texture of the terrain. Also, analysis of the raw vertical axis acceleration is used to determine when the sportsperson is airborne.

For the accelerations along the track, the peak signal within a target frequency range is used to determine the rate at which the sportsperson is moving, in other words a rate of running or cycling, for example, and the magnitude of this peak is used to identify the effort being used.

Generation of a model of the terrain that has been followed, based on the track along the ground of the route taken by the user takes place as a set of points in a three-dimensional space. potentially connected together to form a triangulated irregular network. A first stage involves generating a three-dimensional mesh for the actual route, based on the actual route data and using an estimate of the width of the path. The terrain can thcn bc cxpandcd by progrcssivcly adding additional artefacts to thc outside of the mesh for the path, using increasing sizes of each element as they get further from the actual path. The heights of each newly generated three-dimensional point can either be derived purely from the path heights using extrapolation, or can be performed using a combination of path data and imported real-world height data if an absolute position reference is available, for example, where GPS is used as an input to stabilise the inertial measurement data.

It is thus possible to generate a three-dimensional telTain model using a telTain- topography motion capture system. It is also possible to provide such a three-dimensional terrain model with a three-dimensiona' animated user model travelling therealong. A terrain-topography motion capture system can also be provided which utili ses inverted stabili sed inertial measurement data to determine terrain-topography point data, thereby enabling the terrain model to be generated from data captured from the user's movement along the terrain. The system can be utilised for modelling any telTain and any performance, including but not limited to cycling, moto-X, running, skateboarding, skiing, snowboarding, kayaking, surfing. kite-surfing and windsurfing.

The embodiments described above are provided by way of examples only. and various other modifications will be apparent to persons skilled in the art without departing from the scope of the invention as defined by the appended claims.

I

Claims (10)

1. Claims 1. A terrain-topography motion capture system comprising an inertial measurement element which is mountable on a user or user's equipment at a location having a determinable distance relative to a user/terrain contact point and which is able to determine a position, motion and attitude of the user and/or equipment; a stabilisation element for preventing or limiting integration drift of inertial measurement data of the inertial measurement element; a data storage element for storing the inertial measurement data; a data processing unit including a data inverter for inverting stabilised inertial measurement data to determine terrain- topography point data, and a terrain-model generator for generating a three- dimensional terrain model of a travelled path based on consecutive said terrain- topography point data; and a display for outputting the generated three-dimensional terrain model.
2. 2. A terrain-topography motion capture system as claimed in claim I. wherein the IS data processing unit further indudes a user-model generator for generating a three-dimensional animated user model to be included with the terrain model, animated user motion of the animated user model being based on the inertial measurement data of the inertial measurement element. stabilisation data of the stabibsation element, and the activity being undertaken.
3. 3. A terrain-topography motion capture system as claimed in claim 2, further comprising an activity selector for selecting an activity type from amongst a plurality of different activity types, the data processing unit including a predefined base activity-data set relating to the selected activity type, the user-model generator utilising the predefined base activity-data set when generating the animated user model.
4. 4. A telTain-topography motion capture system as claimed in claim 2 or claim 3, wherein the data processing unit can output the generated terrain model and animated user model to the display as a third-person view animation.
5. 5. A terrain-topography motion capture system as claimed in any one of claims 2 to 4, wherein the animated user model is three-dimensional.
6. 6. A terrain-topography motion capture system as claimed in any one of the preceding claims, further comprising a time-stamping circuit for time stamping the inertial measurement data of the inertial measurement element and the stabilisation data of the stabilisation element, thereby enabling correlation.
7. 7. A terrain-topography motion capture system as claimed in any one of the preceding claims, further comprising a terrain selector for selecting a terrain type from amongst a plurality of different terrain types, the data processing unit including a predefined base terrain-data set relating to the selected terrain type, the terrain-model generator utilising the predefined base terrain-data set when generating the terrain modeL
8. 8. A telTain-topography processing unit as claimed in any one of claims I to 7, wherein the telTain-model generator enables extrapolation of the telTain-topography point data to terrain-topography path data, the terrain model of the travelled path being generated based on the terrain-topography path data.
9. 9. A terrain-topography motion capture system as claimed in any one of the preceding claims, wherein the time-stamping circuit is able to time stamp the stabilisation data of the stabilisation element for time correlation with the inertial measurement data.
10. 10. A terrain-topography motion capture system as claimed in claim 9, wherein the data storage dement is able to store the time-stamped stabilisation data.I. A terrain-topography motion capture system as claimed in any one of the preceding claims, wherein the inertial measurement element compnses a three-axis accelerometer and a three-axis gyroscope.12. A terrain-topography motion capture system as claimed in any one of the preceding claims, wherein the stabilisation element comprises at least first and second stabilisation devices which are different from each other.1 3. A terrain-topography motion capture system as claimed in claim 1 2, wherein the first and second stabilisation devices are a magnetometer and a g1oba positioning system [GPSJ, respectively.14. A terrain-topography motion capture system as claimed in claim 12 or claim 13, wherein at least the first stabilisation device is housed together with the inertia' measurement element, so as to be wearable by a user and/or mountable on user's equipment.15. A terrain-topography motion capture system as claimed in any one of claims 11 to 14, wherein at least the second stabilisation device is housed separately of the inertial measurement system.16. A terrain-topography motion capture system as claimed in claim 15, wherein the second stabilisation device is housed together with the data processing unit.17. A terrain-topography motion capture system as claimed in any one of the preceding claims, wherein the data processing unit is pail of a mobile-computing device.18. A terrain-topography motion capture system as claimed in claim 17, wherein the mobile-computing device is a mobile-telecommunications device.19. A terrain-topography motion capture system as claimed in claim any one of the preceding claims, wherein the terrain-model generator further comprises an environment data input for use during generation of the telTain model.20. A terrain-topography motion capture system as claimed in claim Ic,wherein the environment data input is derived from an optical image recorder.21. A terrain-topography motion capture system as claimed in claim 20, wherein the optical image recorder is mountable on a user and/or a user's equipment.22. A terrain-topography motion capture system as claimed in any one of claims 19 to 21, wherein the environment data input is at least in part remotely receivable from a third party data source.23. A terrain-topography motion capture system as claimed in claim 22, wherein the third party data source provides geographic information system [GIS] mapping data.24. A terrain-topography motion capture system as claimed in any one of claims 19 to 23, wherein the environment data input is at least in part receivable from an environment selector for selecting an environment type from amongst a plurality of different environment types, the data processing unit including a predefined base environment-data set relating to the selected environment type, the terrain-model generator utilising the predefined base environment-data set when generating the said telTain model.25. A terrain-topography motion capture system as claimed in any one of the preceding claims, further comprising a key-event detector which determines key-event points based on position, motion andior attitude derived from the inertial measurement element, the key-event points being locatable on the said IS terrain model and viewable via the display.26. A terrain-topography motion capture system substantially as hereinbefore described with reference to the accompanying drawings.27. TelTain-topography motion capture apparatus for use with a terrain-topography motion capture system as claimed in any one of the preceding claims, the apparatus comprising a housing which is removably mountable to a user andlor a user's equipment, and the inertial measurement dement and stabilisation element within the housing.28. Terrain-topography motion capture apparatus as daimed in claim 27, further comprising the data storage element, the data processing unit, the terrain-model generator. and/or the display on or in the housing.29. A method of generating a three-dimensional terrain modd using a terrain-topography motion capture system as claimed in any one of claims I to 26, the method comprising the steps of: a] determining position, motion and attitude of a user and!or a user's equipment from stabilised inertial measurement data derived from a user moving along terrain; b] inverting the stabihsed inertial measurement data; and c] generating and displaying a three-dimensional terrain model derived from the inverted stabilised inertial measurement data.30. A method as claimed in claim 29. wherein, in step ci. a three-dimensional animated user model is included on the terrain model.31. A method as claimed in claim 30, wherein a viewpoint of the animated user model can be switched between third-person view and first-person view.32. A method as claimed in any one of claims 29 to 31, further comprising environment data which is incorporated into the terrain model and which is at least in part remotely receivable from a third party data source.33. A method as claimed in claim 32. wherein the environment data is derivable from at least satellite imagery.