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REFERENCE LINE APPROACH FOR VECTOR DATA COMPRESSION

Alexander Akimov, A lexander Kolesnikov and Pasi Fränti. DEPARTMENT OF COMPUTER SCIENCE UNIVERSITY OF JOENSUU JOENSUU, FINLAND. REFERENCE LINE APPROACH FOR VECTOR DATA COMPRESSION. October 26th, 2004, Singapore. Overview. The problem formulation The compression approach

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REFERENCE LINE APPROACH FOR VECTOR DATA COMPRESSION

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  1. Alexander Akimov, Alexander Kolesnikov and Pasi Fränti DEPARTMENT OF COMPUTER SCIENCE UNIVERSITY OF JOENSUU JOENSUU, FINLAND REFERENCE LINE APPROACH FOR VECTOR DATA COMPRESSION October 26th, 2004,Singapore

  2. Overview • The problem formulation • The compression approach • The reference line approach • Experiments results • Conclusion

  3. Digital contours compression Vector maps Digital curves

  4. The format of the input data … 151.540252685547 -24.045833587646 151.531372070313 -24.058473587036 151.537963867188 -24.086318969727 151.565521240234 -24.096805572510 151.614135742188 -24.052780151367 151.616073608398 -23.998264312744 151.639846801758 -23.977359771729 151.683868408203 -23.988887786865 151.788024902344 -24.098888397217 151.880798339844 -24.181110382080 151.906097412109 -24.194442749023 151.933441162109 -24.217914581299 … … 3615352.400410958100 6925890.769574328300 3615349.496574054000 6925888.629083023400 3615344.456107155900 6925889.399259801000 3615331.372342015200 6925890.789578920200 3615322.198857250600 6925894.370400821800 3615306.186506596400 6925915.655286318600 3615291.989054007000 6925941.021108507200 3615279.119776819400 6925959.455339696300 3615261.977239642800 6925983.690902458500 3615256.334556568400 6925997.444059205200 3615256.821279231000 6926008.476591490200 3615262.628953038700 6926012.747571803600 …

  5. The quantization approach Quantized curve Original curve

  6. DPCM approach in coordinates quantization xi = xi – Pred(xi) yi = yi – Pred(yi) Original map (X, Y)

  7. The multiresolution vector map compression Choose decoding accurancy ... ... Layer 1 . . . Layer K . . . . Low resolution . . Layer N . . . Average resolution Compressed file High resolution

  8. Two level resolution vector map compression (1) • Instead of N use only two resolution layers • Low resolution layer is a result of rough • approximation of high resolution layer • Lossy compression of high resolution layer • Lossless compression of low resolution layer

  9. Two level resolution vector map compression (2) + = Two level resolution Low resolution High resolution

  10. The reference line approach Y Y’ X’ X Original coordinates Transformed coordinates

  11. Prediction in transformed coordinates: first approach ...

  12. Prediction in transformed coordinates: second approach

  13. Test data Test data #1: 365 curves; 169673 points; 5205 segments. Test data #2: 3495 curves; 221110 points; 13246 segments.

  14. Experiments: test set #1

  15. Experiments: test set #2

  16. Conclusions

  17. The end

  18. Appendix 1: test data #1

  19. Appendix 2: test data #2

  20. Appendix 3: Strong quantization

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