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REFERENCE LINE APPROACH FOR VECTOR DATA COMPRESSION

Learn about the reference line approach for compressing digital contours and maps, quantization strategies, multiresolution vector map compression, experimental results, and conclusions.

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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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