Abstract:
The present invention provides a system for visualising a surface structure of an object. The system includes a camera for taking a plurality of images of the object and a location monitor for monitoring a respective location associated with each image that the camera takes. The system also includes a micro-processor, a display for displaying the surface structure of the object and a software routine for the micro-processor. The software processes the plurality of images and takes into account the respective location associated with each image such that the surface structure of the object can be visualised by the display.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to system for visualising a surface structure and particularly, although not exclusively, to a system for producing a parametric image of an object.  
       BACKGROUND OF THE INVENTION  
       [0002]     The visualisation of a surface structure, such as the visualisation of a three-dimensional structure of an object or the visualisation of a surface structure that is difficult to see by the naked eye, has a range of important applications. For example, archaeological objects are often damaged and surface structures are difficult or impossible to see. Further, in forensic or criminal investigations surface structures may relate to important evidence such as imprints on blank pages of a book resulting from handwritten information on removed pages of the book.  
         [0003]     Recently a technique has been developed that can be used to visualise such surface structures. Initially a number of images are taken either from different positions around an object having the surface structure or from one position with the object being illuminated from different directions. The camera position or illumination source positions are either recorded or predetermined and therefore known. Typically digital images are taken and the images are then processed by a computer.  
         [0004]     The computer executes a texture mapping software, such as polynomial texture mapping (PTM) software. The software divides each image into a plurality of polygons taking into account the known positions of the camera(s) and/or light source(s) and generates a parametric image of the object that visualises the surface structure.  
         [0005]     Typically a total 30 to 50 digital images are taken. For example, an arrangement supporting one or more cameras and a range of illumination sources around the object may be used for this purpose. Alternatively, a single camera or a single illumination source may be moved to predetermined positions around the object and the images may be taken in a sequential manner. In this case an arrangement is required that supports the camera or the illumination sources at the predetermined positions.  
         [0006]     Further, it was recently proposed to place a reflective surface near the object and to use reflections from the reflective surface in each image to calculate the relative position of the camera and illumination source relative to the object. In this case it is not required to move the camera to the predetermined positions or to record the positions at which each image was taken by the camera.  
         [0007]     Each of the described techniques has specific disadvantages. It is either required to have a particular arrangement for taking the images or it is required to record the camera position and/or illumination source position for each image. Alternatively, it is required to position a shiny surface near the object. Accordingly, there is a need for an advanced technical solution that addresses the above-described shortcomings.  
       SUMMARY OF THE INVENTION  
       [0008]     Briefly, the present invention provides a system for visualising a surface structure of an object. The system includes a camera for taking a plurality of images of the object and a location monitor for monitoring a respective location associated with each image that the camera takes. The system also includes a micro-processor, a display for displaying the surface structure of the object and a software routine for the micro-processor. The software processes the plurality of images and takes into account the respective location associated with each image such that the surface structure of the object can be visualised by the display.  
         [0009]     The invention will be more fully understood from the following description of specific embodiments. The description is provided with reference to the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a schematic representation of a system for visualising a surface structure according to an embodiment of the invention;  
         [0011]      FIG. 2  is a schematic representation of a system for visualising a surface structure according to another embodiment of the invention;  
         [0012]      FIG. 3  is a schematic representation of a system for visualising a surface structure according to a further embodiment of the invention;  
         [0013]      FIG. 4  is a flow-chart for a method embodiment of the invention;  
         [0014]      FIG. 5  is a flow-chart for another method embodiment of the invention; and  
         [0015]      FIG. 6  is a flow-chart for a further method embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF EMBODIMENTS  
       [0016]     Referring initially to  FIG. 1 , a system for visualising a surface structure according to an embodiment of the invention is now described.  FIG. 1  shows a system  100  which includes a housing  102  that is moveable around an object  104 . The housing  102  includes a camera  106 , a location monitor  108  and a light source  110 .  
         [0017]     The camera  106  takes an image of the object  104  at each of a plurality of positions around the object  104 . At each location the location monitor  108  monitors the location of the housing  102  with the camera  106  and the light source  110 . In this embodiment the camera  106  and the location monitor  108  are electronic devices and produce electronic data that is directed to personal computer  112  for processing. For example, the housing  102  with camera  106 , location monitor  108  and light source  110  may be moveable by an operator and may be a hand-held device.  
         [0018]     The object  104  may be an archaeological object or an object that is a subject of a forensic or criminal investigation. For example, the object  104  may have a plurality of faces and each face may have a structured surfaces which can be visualised using the system  100 .  
         [0019]     In this embodiment the personal computer  112  includes software for polynomial texture mapping (PTM). In operation, the software divides each of the plurality of images into a plurality of polygons. The software utilises the information from the location monitor and the different illumination levels of the polygons in different images to produce a texture mapping of the object and generates a parametric image on display  114 . The system  100  has the significant advantage that the location monitor records the location of the housing  102  (including camera  106  and light source  110 ) and it is not necessary to use a complicated arrangement for supporting light sources and cameras around the object. Further it is not necessary to position a reflecting surface in the proximity of the object  104  or to manually record the position of the camera or of the light source. Therefore, system  100  significantly simplifies recording of images for generating parametric images and to visualise surface structures.  
         [0020]     In a variation of the above-described embodiment the system  100  may be used to visualise a three-dimensional object. In this case the computer  112  may not include PTM software but may be equipped with software for calculating views of a three-dimensional model of the object from the image and location monitor data.  
         [0021]     In a further variation of the embodiment shown in  FIG. 1 , the light source  110  may not be in one housing together with the camera  106 . For example, the light source  110  may be positioned spaced apart from the camera  106  and may illuminate the object  104  from a stationary position when the camera  102  is moved around the object  104 . Alternatively, the light source  110  may be moved independently from the camera  106 .  
         [0022]      FIG. 2  shows a system  200  which includes a housing  202  that is moveable around an object  204 . The housing  202  includes a location monitor  208  and a light source  210 . The system also includes a camera  206  which in this embodiment is stationary. The camera  206  takes an image of the object  204  for each of a plurality of positions of the light source  210  around the object  204 . The location monitor  208  monitors the location of the light source  210  for each position. In this embodiment the camera  206  and the location monitor  208  are electronic devices and produce electronic data that is directed to personal computer  212  for processing. The personal computer  212  includes software for polynomial texture mapping (PTM).  
         [0023]     In operation, the software divides each image into a plurality of polygons. The software utilises the information from the location monitor and the different images to a produce a texture mapping and to generate a parametric image of the object on display  214 . This embodiment has similar advantages as the embodiment shown in  FIG. 1 . It is not necessary to use a complicated arrangement for supporting light sources and cameras around the object  204 , to position a reflecting surface in the proximity of the object  104  or to manually record the position of the camera or of the light source.  
         [0024]      FIG. 3  shows system  300  which includes a housing  302  and an object  304  which is coupled to a location monitor  308 . The object  304  with location monitor  308  is moveable around the housing  302  which includes a camera  306  and a light source  310 . The camera  306  takes an image of the object  304  for each of a plurality of positions of the object  308  around the housing  302 . At each location of the object  304  the location monitor  308  monitors the location of the object  304 . In this embodiment the camera  306  and the location monitor  308  are electronic devices and produce electronic data that is directed to personal computer  312  for processing. The personal computer  312  includes software for polynomial texture mapping (PTM) and operates in the same manner as personal computers  112  and  212  shown in  FIGS. 1 and 2  respectively and generates a parametric image on display  314 .  
         [0025]     Again, it is not necessary to use a complicated arrangement for supporting light sources and cameras around the object, to position a reflector surface in the proximity of the object  304  or to manually record the position of the camera or of the light source and taking images to generate a parametric image of an object therefor is significantly simplified.  
         [0026]     The location monitors  108 ,  208  and  308  may include a GPS receiver for receiving Global Positioning System (GPS) signals. In use, the location monitor receives the GPS signals and generates electronic data for the approximate location. Additionally or alternatively, the location monitor  108 ,  208  and  308  may include a gyroscope such as an accelerometer which is used for the more precise determination of the location. An accelerometer typically measures acceleration by detecting an angular rate associated with a turning object. For example, the accelerometer may be a device that measures the angular rate using a capacitance system that may form a part of an integrated device.  
         [0027]     The cameras  106 ,  206  and  306  are in this embodiment digital still-cameras. In a variation of these embodiments, video cameras may be used. The digital image data generated by the cameras  106 ,  206  and  306  are stored in a memory of the computer  112 ,  212  and  312 , respectively together with the respective location data generated by the location monitors  108 ,  208  and  308 .  
         [0028]      FIG. 4  shows a flow chart for a method embodiment of the invention which relates to the system embodiment shown in  FIG. 1 . The flow chart illustrates a method  400  of visualising a surface structure of an object. The method includes the step  402  of moving a camera, a light source and a location monitor to each of a plurality of positions around an object. The object is illuminated and images are taking at each position (step  404 ). The locations of the camera and the light source are monitored (step  406 ) and electronic data about the locations are stored in an electronic memory (step  408 ). The images are then processed using a PTM software routine which uses data from the location monitor (step  410 ) and a parametric image of the object is produced on a display (step  412 ).  
         [0029]      FIG. 5  shows a flow chart for another method embodiment of the invention which relates to the system embodiment shown in  FIG. 2 . The flow chart illustrates a method  500  which includes the step  502  of positioning a camera and moving a light source and a location monitor to each of a plurality of positions around an object. The object is illuminated and images are taking for each illumination condition (step  504 ). The location of the light source is monitored (step  506 ) and electronic data about the location are stored in an electronic memory (step  508 ). The images are then processed using a PTM software routine which uses data from the location monitor (step  510 ) and a parametric image of the object is produced on a display (step  512 ).  
         [0030]      FIG. 6  shows a flow chart for a further method embodiment of the invention which relates to the system embodiment shown in  FIG. 3 . The flow chart illustrates a method  600  which includes the step  602  of moving an object with a location monitor to each of a plurality of positions around a camera with a light source. The object is illuminated and images are taking for each position of the object (step  604 ). The location of the object is monitored (step  606 ) and electronic data about the location are stored in an electronic memory (step  608 ). The images are then processed using a PTM software routine which uses data from the location monitor (step  610 ) and a parametric image of the object is produced on a display (step  612 ).  
         [0031]     Although the invention has been described with reference to particular examples, those skilled in the art will appreciate it that the invention may be embodied in many other forms. For example, the system for visualising a surface structure may not include a housing such as housing  102 ,  202  and  302 . The camera and the illumination source may be individually moveable. In this case both the camera and the illumination source may have an individual location monitor. Further, the system may not necessarily include an illumination source and natural light may be used for illumination. The computers  112 ,  212  and  312  may not be personal computers and may be replaced by processors that are positioned for example in a housing of the displays  114 ,  214  and  314 . Alternatively, the processors may be positioned within the housings  102 ,  202  or  302 .  
         [0032]     As discussed above, the software may not necessarily be arranged for texture mapping but may be used to calculate a three-dimensional model of the object. In this case the software may calculate views of a three-dimensional model of the object from the image and location monitor data.