Restitution Automation

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Restitution Automation

  1. 1. RESTITUTION AUTOMATION FOR CLOSE-RANGE APPLICATIONS<br />Artemis Valanis, Andreas Georgopoulos<br />School of Rural and Surveying Engineering<br />Laboratory of Photogrammetry<br />National Technical University of Athens<br />
  2. 2. Development of a semi- or fully- automated method for the restitution process of image products in the case of close-range applications <br />Applicability of the method for the case of Byzantine monuments<br />Trial applications on other kinds of monuments<br />OBJECTIVES<br />
  3. 3. Construction complexity<br />Presence of decorative elements<br />Tuffstone is the basic construction material<br />OBJECT DESCRIPTION<br />
  4. 4. Extensive research of the properties of the object of interest and trial application of several image processing techniques<br />Development of a method for the detection of the objects of interest<br />Program and interface development<br />Application of the proposed method for Byzantine and other kinds of monuments<br />Evaluation of the results<br />COURSE OF STUDY<br />
  5. 5. Noise reduction methods(mean-, order statistics and adaptive filters)<br />Image enhancement in the frequency domain (FFT, Ideal filters, Butterworth filters)<br />Edge detection algorithms (Sobel, Prewitt, Canny, LoG, color edge detection)<br />Morphological processing (erosion, dilation, morphological gradient)<br />Segmentation and thresholding techniques <br />TRIAL APPLICATIONS OF VARIOUS IMAGE PROCESSING TECHNIQUES<br />
  6. 6. PROBLEMS ENCOUNTERED IN THE DETECTION OF THE OBJECTS<br /> Object complexity<br /> Strong resemblance in the appearance of the stones and joints<br /> Existence of inclinated planes and shadowed areas<br /> Erosion of the construction material <br /> Presence of moisture<br />
  7. 7. PROPOSED APPROACH<br />Sample selection<br />Calculation of the mean value and standard deviation of the gray values of the pixels of the sample <br />Region Growing<br />
  8. 8. ROUTE FOLLOWED BY THE ALGORITHM<br />
  9. 9. REGIONS EXAMINED BY THE ALGORITHM ACCORDING TO THE POSITION OF THE CANDIDATE PIXEL<br />
  10. 10. Connectivity criterion: At least two pixels of the examined region must belong to the object<br />Homogeneity criterion: The arithmetic (mr) mean of the gray values of the candidate and the identified as object pixels of the currently examined regionmust belong in the confidence interval given by Equation [1]<br />ms - z ssmr ms + z ss [1]<br />CRITERIA EVALUATED BY THE ALGORITHM<br />
  11. 11. DETECTION RESULTS FOR A SINGLE OBJECT<br />
  12. 12. Definition of the area to be processed<br />Sample selection for the objects that must be detected<br />Application of an adaptive thresholding technique<br />Improvement of the binary image which is yielded by the thresholding process<br />Exploitation of the improved binary image for the automated sample selection<br />Application of the algorithm for each one of the objects detected<br />AUTOMATION OF THE PROCESS<br />
  13. 13. EXAMPLE<br />
  14. 14. INTERFACE OF THE PROGRAM<br />
  15. 15. APPLICATIONS – BYZANTINE MONUMENTS<br />
  16. 16. EXPERIMENTS FOR THE CASE OF THE DOME<br />
  17. 17. EXPERIMENTS FOR THE DECORATIVE ELEMENTS<br />
  18. 18. FINAL RESULTS AND COMPARISON<br />
  19. 19. Tolerance: σ<br />Tolerance: 2σ<br />Tolerance: 3σ<br />EVALUATION<br />
  20. 20. EVALUATION<br />
  21. 21. The proposed method is very flexible and fast<br />The program used for the application of the developed methods offers a wide range of possibilities and is user friendly<br />The accuracy of the restitution is objectively characterized as satisfactory for the case of Byzantine monuments<br />The restitution process is accelerated by a factor of at least 1.7<br />CONCLUSIONS<br />
  22. 22. Examination of more complex properties such as texture<br />Thorough review and further development of the fully automated method<br />Detailed research of the properties of other kinds of monuments<br />SUGGESTIONS <br />
  23. 23. Thank you for your attention!<br />
  24. 24. VECTORIZATION<br />
  25. 25. ARCH OF ADRIANOS<br />
  26. 26. NATIONAL THEATRE<br />
  27. 27. BYZANTINE WALL(DAPHNI MONASTERY)<br />

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