DIGITAL IMAGERY AND ANALYSIS SYSTEM

Abstract: Apparatus for the 3-D stereometric analysis of surfaces or bodies has a video frame store (15) which receives stereo image pairs on a single frame from a video input device such as a colour T.V. camera (12), CAT-scan (52) or x-ray machine (53). The stereo image pairs are fed to an analog/digital multiplexing unit (18) and to a microprocessor (20) which incorporates software to control the apparatus and to analyse the images. When the images are processed, the system incorporates correlating means (19) to reconstitute image positions for identical object points in both images.

Description: - 1 - Title: "DIGITAL IMAGERY AND ANALYSIS SYSTEM" BACKGROUND OF THE INVENTION (1) Field of the Invention THIS INVENTION relates to digital imagery and analysis system. (2) Prior Art There are many potential applications for a system for non-destructive measurement of the geometric parameters of surfaces, and in particular, for such measurements of touch sensitive surfaces. In such applications, emphasis on objectivity is required. The potential applications include: (a) medicine e.g. monitoring external changes in facial or limb configurations due to congenital mal- formations, disease or injury; measurements may also be obtained from.internal examination with alternative scanning devices; the system enables the special measure¬ ment data necessary for body reconstruction and the development of prosthetic replacement parts and the precise measurements required for reconstructive surgery in the determination of the reconstruction of body parts such as face, ears, nose and genitals. (b) forensics e.g. reconstruction of faces from a skeletal or partially decomposed base or "Identikit" type reconstruction of faces; (c) engineering e.g. monitoring of engineering structure deformation, monitoring the stability of rock slopes, faces, ore stockpiles; measurement of the volume of ore bodies and stockpiles; monitoring surfaces under stress; exploration drilling analysis; automatic terrain evaluation; and monitoring of equipment in measurement of wheel wear/deformation on railway rolling stock and railway track wear/deformation; (d) the manufacturing industry e.g. quality controls; and (e) the military e.g. target analysis and identification. Various systems for such analysis have been proposed but these have generally proved fairly inflexi- ble and limited in scope to laboratory tools only. SUMMARY OF THE PRESENT INVENTION It is an object of the present invention to provide a system which can measure the geometric para¬ meters of a surface with emphasis on objectivity. It is a preferred object to provide a system which can be controlled by an operation using a computer/microprocessor. It is a further preferred object to provide a system which can be used for continuous or single frame processing. It is a further preferred object to provide a system which can be incorporated into a system which also receives image from intrusive image devices. Other preferred objects will become apparent from the following description. In one aspect the present invention resides in apparatus for 3-D stereometric analysis of surfaces including: means to generate a stereo image pair of the surface being measured; means to convert the analog signals corres¬ ponding to the image pair to respective digital signals; checking the correlation between the respective digital signals; and processing the digital signals to produce an output. The means to generate the stereo image pair may include an optical mirror and filter arrangement mounted on a base-bar to produce two geometrically different images on a light sensitive video tube e.g. of a colour video camera, a pair of spaced video cameras, ultra¬ sound or x-ray sources. The analog signals may be stored e.g. in a video tape recorder and/or may be passed for on-line processing. Preferably the signals are passed through a monitor to enable the operator to observe the signals being transmitted for processing. Preferably the analog signals are converted to digital signals via an A/D multiplexing circuit and then fed to a digital correlation to reconstitute the image positions for identical object points in both images, in order to compute the 3-D object position of such points. The signals are preferably processed by a suitable computer/microprocessor and the output may be fed to the monitor, an exterial storage unit and/or a printer/plotter is required by the operator who may control the system from a control panel incorporating a key board. In a second aspect the present invention resides in a digital imagery and analysis system for a 3-D object including: means to generate image pairs of the object; means to convert the analog signals corres- ponding to the images into respective digital signals and storing the digital signals in a data archive; and means to process the digital signals to produce an output corresponding to the images. The image pair generating means may include the video system for generating the stereo image pairs hereinbefore described NM , CAT-scan, x-ray, ultra¬ sound and like image generating devices. The output may be fed to a central analysis and archive unit for processing or the operator can call up data and images from that unit to enable comparison of the generated images with the called data and images. BRIEF DESCRIPTION OF THE DRAWINGS To enable the invention to be fully understood, preferred embodiments will now be described with refer- ence to the accompanying drawings in which: FIG. 1 is a schematic layout of a video imaging system for 3-dimentional analysis of surfaces; and FIG. 2 is a schematic layout of a multi- input digital image archive and data base system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, the stereo image pair of the object e.g. a human head 10, is produced by an optical mirror and filter arrangement 11 mounted on a base-bar. A green filter and a red filter and two mirrors in each half of the light path provide superimposition of the two geometrically different images of the object 10 onto the light sensitive video tube of a colour video camera 12 so that each of the two images can be retrieved separately from the monitor. The output from the video camera 12 is fed to a video tape recorder (VTR) 13 for in situ image capture without on-line processing and/or reprocessing of image pairs captured (and possibly processed) earlier. (For on-line processing, the VTR 13 is bypassed.) The signals are passed through an analog filter 14 to a video frame store 15. The filter unit 14 removes noise and very low frequency signals from the video signal. The filter unit is preferably a variable band pass filtering unit which may be controlled manually and/or digitally by the microprocessor. The video frame store 15 enables single frame processing of the signals. The still composite video signal is fed to a colour monitor 16 in order to display the stored and filtered video frame, separate the red and green signals from the composite video (for restoratioa of the two video images), allow VDU display controlled by the micro- processor and/or allow for an optional display of graphic overlay generated by the microprocessor software system from measurement data. The red and green signals (forming the left and right stereo images respectively) are fed to a chain of signal delay lines 17, A/D converters (for multiplexing) 18 and a digital signal correlator 19 to reconstitute image positions for identical object points in both images. These image positions are required in order to compute the 3-D object position of such points. The number of points surveyed depends on the overall resolution of the system (e.g. the number of image lines and number of image line elements produced by the A/D converter timing unit and the resolution accuracy of the delay lines). The digital signal delay in front of the cor¬ relator unit will have a resolution of one image line element as produced by the A/D conversion. Subsequent correlation can be done directly to the same resolution and to about half that interval by analysis within the microprocessor correlation control real time loop. An improvement of this resolution is achieved by the two analog delay lines in front of the A/D converter. These delays will have a delay range in the magnitude of +- one line element timing interval as used by the A/D conversion and essentially they act as a fine tuning system. Both delay lines (the analog and the digital delay) are under control of the microprocessor real time loop which in turn also references to time signals such as the A/D converter clock and the video sync pulse in order to evaluate the image position of a matching point. The sync pulse count will give the image line position, while the A/D clock pulse count plus the delay on the left signal line will provide for the in-line position of a matching point in the left image, and for the right image respectively using the right signal line delay. (Connections for sync pulse and A/D clock are not shown in the drawings. ) Image position determination and sequence is fully under control of the software in the micro¬ processor 20. Accuracies of image position determination will be: for line count at a level of video line resolution; for in-line count better than A/D conversion resolution only limited by the definition of the filtered video signal. Thus, it is expected to gain an improvement by having the filter unit(s) also under software control. As outlined above indirectly, the measurement procedure is controlled by microprocessor software. An Intel iSBC 286 single board computer system may be used as this microprocessor type is software compatible with 8086 and 8088 microprocessors which can also be utilized in systems requiring lower processor speeds. User interaction with the system is achieved at measurement and data analysis stages via a control panel and keyboard unit 21 as well as through VDU capa- bility and optional graphics display on the image display monitor 16. Optionally a printer/plotter 22 can be connected for hard copy output as well as a digital mass storage system 22 in form of magnetic disk or tape systems (floppy disc, mag. tape cassette, etc.). The software package for the system can be developed to achieve: real time loop for control of .image correlation; solution for imaging equations (co-linearity equations) ; solution for corrective functions (lens distortion, non-linearity in signal path in particular during line generation and delays); measurement sequence control; 3-D position data presentation; routines to derive information such as distances, angles, volumes, etc.; refined analysis routines according to applications; and optional graphics functions according to applications. The video system, shown generally in the dotted line box 50, provides non-intrusive images of the human head 10. Where the surface features under study are to be related e.g. to bone structure, muscle and other tissue formation, image pairs can be obtained from intrusive image sources e.g. nuclear magnetic resonance (NMR), CAT-scan, x-ray and ultrasound devices and their inputs fed to the video image frame store for processing in the manner hereinbefore described. This enables the data base or the item under study to be markedly increased. In certain applications, the analog and digital delays can be simulated by the software and so the out¬ put from the video frame store 15 can be fed direct to the A/D converter 18 and the microprocessor 20, as indicated by the dashed lines. Referring now to FIG. 2, the imagery system described above can form the part of an on-line imagery and analysis system shown schematically in FIG. 2. The image pairs generated by the video system 50 and from the NMR 51, CAT-scan 52, x-ray 53 and ultra¬ sound 54 devices can be fed through a suitable in/out device 55, together with data stored on a disk or tape storage unit 56, into a data archive 57- A user, operating e.g. a keyboard 58, can call up the data through an operating system 59 and an analysis system 60 which converts the data in the archive 57 into a form suitable for the user. The out¬ put data from the system may be displayed e.g. on a VDU and/or supplied as a hard copy e.g. on a printer on a display and/or output unit 61. The output data can also be fed to a computer-aided-manufacturing (CAM) unit 62 which could control e.g. a numerically controlled milling machine in which are manufactured prosthesis for home replacement surgery. The operating system 59 can be connected e.g. via modems and landlines to a central analysis unit 63 to which is connected a central archive unit 64 and inputs/outputs 65 manned by experts in the field. For example, the central archive and analysis system could be installed in a major city and the on¬ line systems provided in a number of " regional cities. A doctor in a regional city could send the images of a patient to the central archive and analysis system for consideration and comment by specialists in the field or could call for data relating to particular diseases or disabilities, including images of persons suffering such diseases and showing how the diseases progress. By comparing the patient's images with the retrieved data and images, improved diagnosis of the disease, and its status and treatment can be provided. While the system has immediate application in the medical field, it will be readily apparent to the skilled addressee that by selection of suitable imagery input devices, and appropriate controlling of analysis software, the system has a wide range of potential applications. Various changes and modifications may be made to the embodiments described without departing from the scope of the present invention defined in the appended claims.

Claims: CLAIMS 1. Apparatus for 3-D stereometric analysis of surfaces including: means to generate a stereo image pair of the surface being measured; means to convert the analog signals corres¬ ponding to the image pair to respective digital signals; checking the correlation between the res¬ pective digital signals; and processing the digital signals to produce an output. 2. Apparatus as claimed in Claim 1 wherein: the means to generate the stereo image pair includes an optical mirror and filter arrangement mounted on a base-bar to produce two geometrically different images on a light sensitive video tube of a colour video camera; a pair of spaced video camera; a pair of x-ray sources or a pair of ultrasound sources. 3. Apparatus as claimed in Claim 1 wherein: the analog signals are converted to digital signals via an A/D multiplexing circuit and this is fed to a digital correlation unit to reconstitute the images position for identical object points in both images. 4. A'digital imagery and analysis system for a 3-D object including: means to generate image pairs of the object; means to convert the analog signals corres¬ ponding to the images into respective digital signals and storing the digital signals in a data archive; and means to process the digital signals to produce an output corresponding to the images. 5. . Apparatus as claimed in Claim 4 wherein: the image pair generating means includes a video image pair generating system, NMR, CAT-scan, x-ray and ultrasound image generating devices. - 1 1 - 6. Apparatus as claimed in Claim 4 wherein: the output is fed to a central analysis and archive unit for comparison with data and images stored in the unit. 7. Apparatus as claimed in Claim 5 wherein: the output is compared with data and images called up from a central analysis and archive unit.

Inventors: DOWIDEIT GERD RUDIGER, NEWMAN DENIS GENE, DOWIDEIT, GERD, RUDIGER, NEWMAN, DENIS, GENE
Applicants: UNIV QUEENSLAND, UNIVERSITY OF QUEENSLAND
Application year: 1986
Main classification: H04N7
IPC codes: A61B5, A61B6, G06T1, G06T7, H04N7, H04N13