Abstract:
A terrain visualization device is disclosed, the device comprising a wearable mounting structure adapted to be fixed to a user. The device also includes a light emitting unit attached to the mounting structure and configured to project a predetermined contrast pattern onto terrain when the mounting structure is fixed to a user. Also disclosed is a method for traversing terrain comprising fixing a wearable mounting structure to a user, the mounting structure having a light emitting unit attached thereto, traversing the terrain, and projecting a predetermined contrast pattern onto the terrain using the light emitting unit, so that the topography of the terrain can be determined from distortion of the contrast pattern. A method for illuminating a ski run is also disclosed.

Description:
RELATED APPLICATIONS 
       [0001]    The present application is a National Phase entry of PCT Application No. PCT/GB2011/000955, filed Jun. 24, 2011, which claims priority from Great Britain Application Number 1014599.3, filed Sep. 2, 2010, the disclosures of which are hereby incorporated by reference herein in their entireties. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a terrain visualization device that projects a pattern of light onto the terrain, allowing a user to see the topography of the terrain even in poor lighting conditions. The invention also relates to a method for traversing terrain and a method for illuminating a ski run. 
       BACKGROUND 
       [0003]    There is a common problem encountered in skiing when lighting conditions are poor, whether due to low cloud or the time of day. In such conditions, sunlight may not produce shadows on the snow, either due to the sun being obscured by cloud or due to the position of the sun in the sky. It is very difficult for a skier to see the topography of the terrain without shadows on the snow because the snow-covered ground appears as a uniform white sheet, without colour color or luminance contrast. 
         [0004]    The above problem is particularly dangerous in winter sports such as skiing, snowboarding and mono-skiing, where it can lead to accidents caused by the skier unexpectedly either leaving the ground or hitting a bump in the snow. However, the same problem is encountered when traversing snow-covered ground by any means including walking and driving a vehicle. 
         [0005]    A similar problem is also encountered when traversing other types of terrain that are uniform in appearance and do not provide sufficient color or luminance contrast to see their topography in poor light. For example, the problem can also be encountered in water sports such as waterskiing in low light, or when hiking at night. 
       SUMMARY OF THE INVENTION 
       [0006]    Embodiments are designed to overcome the above problems by allowing a user to see the topography of terrain despite poor lighting conditions. Embodiments are designed to achieve this using much less energy than would be required to fully illuminate the terrain. 
         [0007]    According to an embodiment, there is provided a terrain visualization device comprising a wearable mounting structure adapted to be fixed to a user; and a light emitting unit attached to the mounting structure and configured to project a predetermined contrast pattern onto terrain when the mounting structure is fixed to a user. 
         [0008]    The pattern projected by the light-emitting device is distorted by the terrain as seen by the user. Since the user is familiar with the undistorted shape of the pattern, as projected onto flat ground, the user can easily deduce the shape of the terrain from the distorted pattern and can react accordingly. There is no need for the user to actually be able to see features of the terrain, its shape is inferred by the distortion of the pattern. Hence, an embodiment operates completely differently from a conventional illumination device. A conventional illumination device would require sufficient power to illuminate the entire area of terrain ahead of the user, whereas an embodiment only projects onto a fraction of that area and relies on contrast between the projected pattern and the surrounding terrain rather than illumination of the terrain itself. 
         [0009]    In other words, an illumination device such as a headlight must illuminate the terrain with sufficient power that a visible luminance contrast is created by differences in reflectivity of the terrain as seen by the user. On the other hand, an embodiment creates its own luminance contrast by projecting a pattern, which requires much less power. 
         [0010]    In an embodiment, the light emitting unit includes a laser light source. Suitably, the laser light source is a class 1 laser. In an embodiment, the laser light source has a power output of 5 mW or less. 
         [0011]    Alternatively, the light emitting unit includes a superluminescent diode light source. Suitably, the mounting structure is one of a belt, a belt clip, an arm strap and a head strap. Conveniently, the mounting structure is a belt and the light emitting unit is attached to a buckle of the belt. 
         [0012]    In an embodiment, the mounting structure includes a light source holder and the light emitting unit is detachably attached to the light source holder. 
         [0013]    In an embodiment, the predetermined contrast pattern comprises at least one of a line and a dot. For example, in one embodiment the predetermined contrast pattern is a two-dimensional pattern of lines and/or dots. 
         [0014]    Using a pattern of lines and/or dots reduces the surface area of the projected pattern and hence the power consumption of the device, while providing a clearly visible contrast pattern. Using a two-dimensional pattern allows the user to see the shape of the terrain in three dimensions without difficulty. 
         [0015]    Suitably, the predetermined contrast pattern comprises a plurality of dots. 
         [0016]    In an embodiment, the predetermined contrast pattern comprises a straight line. 
         [0017]    Conveniently, the predetermined contrast pattern comprises at least one of an arc, a regular polygon, a circle, a cross, a grid and a regular dot array. For example, in one embodiment the number of lines in the predetermined contrast pattern is between 1 and 4. 
         [0018]    Using a straight line or a regular shape for the projected pattern allows distortion in the pattern to be seen more easily. Straight lines can be advantageous in embodiments because it is easier to manufacture a light source capable of projecting a straight line than one capable of projecting more complex shapes. In particular, using between 1 and 4 lines in the pattern provides a good balance between ease of manufacture and accurate visualization of the terrain. 
         [0019]    In an embodiment, the light emitting unit comprises at least one of a lens and a holographic plate for generating the predetermined contrast pattern. 
         [0020]    In an embodiment, the light emitting unit is adapted to project the predetermined contrast pattern continuously. 
         [0021]    Alternatively, the light emitting unit is adapted to project the predetermined contrast pattern intermittently. Suitably, the light emitting unit is adapted to project the predetermined contrast pattern repeatedly at a preset frequency. In one embodiment, the light emitting unit is adapted to project the predetermined contrast pattern for a preset duration. 
         [0022]    Conveniently, the light emitting unit is adapted to project the predetermined contrast pattern in response to operation of a switch. 
         [0023]    In an embodiment, the light emitting unit is adapted to emit narrowband light. More preferably, the light emitting unit is adapted to emit light in the visible spectrum. 
         [0024]    In one embodiment, the light emitting unit is adapted to emit light outside the visible spectrum. Suitably, the light emitting unit is adapted to emit infra-red light. 
         [0025]    In one embodiment, there is provided a system comprising the device adapted to emit light outside the visible spectrum described above and an optical sensing apparatus, wherein the optical sensing apparatus is adapted to detect the light outside the visible spectrum emitted by the light emitting unit and reflected from the terrain and to display the light outside the visible spectrum as visible light, to allow the user to see the predetermined contrast pattern projected onto the terrain. 
         [0026]    According to another embodiment, there is provided a belt, head strap, helmet, ski, mono-ski, snowboard, shoe or boot comprising the device described above. 
         [0027]    According to a further embodiment, there is provided a method for traversing terrain comprising fixing a wearable mounting structure to a user, the mounting structure having a light emitting unit attached thereto; traversing the terrain; and projecting a predetermined contrast pattern onto the terrain using the light emitting unit while traversing the terrain, so that the topography of the terrain can be determined from distortion of the contrast pattern. 
         [0028]    In an embodiment, the method further comprises skiing, mono-skiing or snowboarding across the terrain. 
         [0029]    According to another embodiment, there is provided a method for illuminating a ski run using a terrain visualization device including a mounting structure and a light emitting unit attached to the mounting structure, the method comprising: fixing the mounting structure to a static object; and projecting a predetermined contrast pattern onto the ski run using the light emitting unit, so that the topography of the ski run can be determined from distortion of the contrast pattern. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    Embodiments of the present invention will now be described by way of further example only and with reference to the accompanying drawings, in which: 
           [0031]      FIG. 1  shows a skier using a device according to an embodiment of the invention; 
           [0032]      FIG. 2  is a schematic diagram of a belt-mounted visualization device according to an embodiment of the invention; 
           [0033]      FIG. 3  is a schematic diagram of a head-mounted visualization device according to an embodiment of the invention; 
           [0034]      FIG. 4  is a schematic diagram of a visualization device according to an embodiment of the invention designed to be clipped to a belt or strap; 
           [0035]      FIGS. 5(A) to 5(F)  illustrate patterns of light emitted by devices according to embodiments of the invention; and 
           [0036]      FIG. 6  illustrates the distortion of a cross-shaped light pattern according to an embodiment of the invention by uneven terrain. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0037]    As shown in  FIGS. 1 and 2 , a device  100  according to an embodiment includes a light emitting unit  102  attached to a mounting structure  104 . The mounting structure  104  includes a belt and a light source holder  106 . The device  100  projects a predetermined contrast pattern of light  108  onto terrain  110  in front of a user. 
         [0038]    In this embodiment, the light emitting unit  102  comprises a laser diode and complies with the ANSI Z136 and IEC 60825 standards. However, any light source sufficiently bright and directional to project a contrast pattern onto a terrain surface from a distance of a few meters can be used. In particular, a coherent light source is not required and a non-coherent source such as a superluminescent diode (SLED) can be used instead. 
         [0039]    The power of the light source must be sufficient in embodiments for the user to see the contrast pattern projected by the light source onto the ground. However, the light source must not be so powerful that it could cause eye injury to the user or other people nearby. Class I lasers, which are eye safe, and SLEDs are particularly suitable as the light source for this reason. A Class 11/2 laser with a power of up to 1 mW is also relatively eye safe and is suitable for use as the light source. A Class IIIa/3R laser with a power of up to 5 mW can be used as the light source but must be operated with due caution. 
         [0040]    The wavelength of the light source is not particularly limited. Of course, any color of visible light can be used but it is also possible to use wavelengths outside the visible spectrum if the device  100  is designed to be used in conjunction with an optical sensing apparatus detecting the wavelength used. For example, it is possible to use an infra-red light source so that the projected pattern can be seen using thermal night vision goggles. A Nd:YAG infra-red laser is particularly suited to be the light source in this embodiment. Using a light source emitting light outside the visible spectrum has the advantage that the projected pattern is only visible to a user with appropriate equipment, such as thermal goggles. This means that the contrast pattern will not distract others nearby, for example other skiers on a ski slope. This embodiment is particularly useful at night, when infra-red night vision goggles would be used in any case. 
         [0041]    The light emitting unit  102  is configured to project a contrast pattern  108  onto the terrain surface. The pattern  108  can be a single line, it is only necessary for the user to be able to detect the topography of the terrain onto which the pattern  108  is projected based on the distortion of the pattern  108 . The device  100  is effective because the user knows the shape of the projected pattern  108  on a flat surface and can thus infer the topography of the terrain by comparing the distorted pattern  108  with the known flat surface pattern  108 . This process quickly becomes intuitive and then does not require conscious thought on the part of the user. 
         [0042]    In this embodiment, the laser diode projects a single straight line pattern  108 . This can be achieved by using a laser diode that has a line-shaped (i.e. relatively long compared to its width) light-emitting area, or by passing light from the diode through a lens or slit in the desired shape. Alternatively a holographic plate can be used to generate the light pattern projection. Suitable methods for generating a line pattern are described in U.S. Pat. Nos. 4,321,551 and 6,069,748, which are hereby incorporated herein by reference in their entireties. 
         [0043]    The light emitting unit  102  is attached to a belt in this embodiment, so that the device  100  can be attached to the waist of a user. The belt has a light source holder  106  fixed to it and the light emitting unit  102  is detachably clipped into the light source holder  106 . However, the light emitting unit  102  can also be integral to the mounting structure  104 . It is preferred that the light emitting unit  102  be detachable in one embodiment so that it can be replaced in the event of failure. 
         [0044]    The light source holder  106  forms part of the buckle on the front of the belt in this embodiment. However, the light source holder  106  can also be fixed to the material of the belt itself, either at the front or to one side. The light source holder  106  holds the light emitting unit  102  in such a way that its position and angle are fixed in use. The light source holder  106  holds the light emitting unit  102  at a position and angle such that when the belt is worn by a user, the light emitting unit  102  projects the pattern  108  onto the terrain in front of the user. In this embodiment, the light emitting unit  102  is held at an angle such that the pattern  108  is projected onto the terrain approximately 2 to 4 m in front of the user when the belt is attached to the user&#39;s waist. The distance in front of the user should be sufficiently short that the pattern  108  is clearly visible but sufficiently far that the user has time to react to changes in the terrain. The optimal distance varies depending upon the expected lighting conditions and speed of the user among other factors, but a distance of between 2 m and 6 m has been found to be suitable for most applications. 
         [0045]    In the above embodiment, the device  100  is mounted to the waist of a user. This arrangement is advantageous because the user&#39;s waist does not tend to move independently as much as other body parts, which makes the pattern  108  projected by the device  100  more stable on the terrain and hence easier to read. However, the device  100  can also be configured to be attached to any other body part of the user. 
         [0046]    A head-mounted device  100  according to another embodiment is shown in  FIG. 3 . The device  100  includes a head strap  112 , which can be attached directly to the head of the user or can be attached to a helmet. A light emitting unit  102  as described above is fixed to a front portion of the head strap  112 . The light emitting unit  102  is configured so that when the head strap  112  is worn by the user, the pattern  108  projected by the light emitting unit  102  is projected onto the ground with the user&#39;s head at a comfortable angle. The head-mounted device  100  has the advantage that the user can select a piece of terrain on which to project the pattern  108  simply by a head movement. This is particularly useful when the user needs to change direction suddenly. 
         [0047]    In the above embodiments, the mounting structure  104  includes the belt or head strap  112 . However, it is also possible to provide a mounting structure  104  consisting only of a light source holder  106  having a belt clip  114  as well as a portion configured to engage with and hold the light emitting unit  102 , as shown in  FIG. 4 . In the embodiment shown in  FIG. 4 , the light emitting unit  102  is fitted into a hole in the light source holder  106 . The mounting structure  104  can then be clipped onto an existing belt or other item of clothing so as to fix the light emitting unit  102  to the user&#39;s waist or other body part. The precise form of the mounting structure  104  is not important to the invention provided that it is capable of securely attaching the light emitting unit  102  to the user&#39;s body. 
         [0048]    This embodiment has the advantage that it can be interchangeably attached to a belt as shown in  FIG. 2 , to a head strap as shown in  FIG. 3  and to a range of other wearable accessories. 
         [0049]    The terrain visualization device  100  can also be clipped or otherwise attached to the front of a vehicle, such as a mountain bike or snowmobile, so as to project the pattern  108  onto the ground and provide terrain visualization when driving the vehicle. 
         [0050]    In an alternative embodiment, the device  100  can be attached to a static object such as a ski lift pylon or a tree. The device  100  is mounted to the static object in such a way that the light source projects the pattern  108  onto a nearby area of terrain, enabling any passer by to see the topography of that piece of terrain. In this embodiment, the mounting structure  104  is adapted to fix the light emitting unit  102  securely to the desired static object so as to point downwards, towards the area of terrain to be illuminated. For example, the mounting structure  104  in one embodiment is an adjustable strap and buckle adapted to be wrapped around the trunk of a tree. 
         [0051]    The light source holder  106  is fixed to the buckle at a downwards-facing angle and friction between the strap and the tree trunk holds the device  100  in position. This embodiment is particularly useful in a ski resort, where specific areas of a ski run may be known to be dangerous. A device  100  according to the invention can be mounted to a static object at the side of the ski run so as to project a pattern  108  onto a dangerous area, for example a steep-sided bump. In this way, any skier coming down the run will be able to see the bump and react appropriately, even in poor light. 
         [0052]    The light emitting unit  102  can be configured to project a wide range of different patterns  108 . A single line has the advantage of simplicity and ease of manufacture. However, a two-dimensional pattern  108  provides greater information on the shape of the terrain in three dimensions. A pattern  108  made up of regular shapes is used in one embodiment because it makes the distortion caused by the underlying terrain more apparent and easier for the user to interpret. However, irregular shapes can also be used. Examples of suitable projection contrast patterns  108  are illustrated in  FIG. 5 . These shapes are a straight line, a cross, a circle, an arc, a grid and a regular array of dots respectively. 
         [0053]    In one modification, the pattern  108  is an array of parallel lines. In an embodiment, this pattern includes between 2 and 4 parallel lines. In an embodiment, the contrast pattern  108  is made up of lines and/or dots rather than large blocks of light because this greatly reduces the power consumption of the light emitting unit  102 . As discussed above, a major advantage of embodiments is that the shape of the terrain is inferred indirectly through distortion of the projected contrast pattern  108 . As a result, there is no need to illuminate a large area of terrain so that the features of the terrain are directly visible. The light emitting unit  102  projects the pattern  108  continuously when the device  100  is switched on in this embodiment. However, the light emitting unit  102  can alternatively be configured to project the pattern  108  intermittently. The light emitting unit  102  can project the pattern  108  at a preset frequency for a present duration, for example at 2 Hz for 100 ms at a time. 
         [0054]    The light emitting unit  102  can also be configured to project the pattern  108  only at certain times of day, for example between sunset and dawn. In this case, the device  100  is further provided with a timer and/or light sensor and circuitry for turning the light source on and off in response to the output of the timer and/or light sensor. Alternatively, in other embodiments, the light emitting unit  102  can only be activated when a low contrast condition is detected. In this case, the device  100  is further provided with a contrast sensor and circuitry for turning the light source on and off in response to the output of the contrast sensor. 
         [0055]    A switch can provided on the device  100  and the light emitting unit  102  can be configured to project the pattern  108  only when the switch is activated by the user. In this way, the power consumption of the device  100  is further decreased because the time for which the light emitting unit  102  is active is reduced. 
         [0056]    The light emitting unit  102  can be powered by an electrical power source such as a battery, as is conventional. 
         [0057]    The foregoing description has been given by way of example only and it will be appreciated by a person skilled in the art that modifications can be made without departing from the scope of the present invention.