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Maplat - Historical map viewer technology that guarantees nonlinear bijective conversion without distortion

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Maplat - Historical map viewer technology that guarantees nonlinear bijective conversion without distortion
Presentation of ICC2019 July 17th

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Maplat - Historical map viewer technology that guarantees nonlinear bijective conversion without distortion

  1. 1. Maplat - Historical map viewer technology that guarantees nonlinear bijective conversion without distortion Kohei Otsuka – Code for History 1
  2. 2. Agenda • About presenter • What is Maplat? • A method of coordinates transformation • Line-to-line conversion • Comparison with Stroly • Application of Maplat • Summary & Proposal 2
  3. 3. About presenter 3
  4. 4. • Kohei Otsuka • Has been working in the location based entertainment business for 15 years • Mapion Inc. (Now One Compath Inc.) - Participated in the launch of the location game called "Keitai Kunitori Gassen" and was in charge of both planning and development directions as well as scenario creation and program implementation. • ATR-Promotions Inc. (Now Stroly Inc.) - Participated in the launch of a smartphone app using historical maps, and was in charge of both planning and development directions as well as program implementation and patent development. • My current main business is technical support for both map content and platform at HERE Technologies. • As an individual volunteer, I have been involved in open source and open data activities, including the development of Maplat, which was announced this time, and am preparing to launch Code for History. 4
  5. 5. What is Maplat? 5
  6. 6. Map viewer technology to enjoy walking around town using historical maps and pictorial maps 6 © OpenStreetMap © Utouto Tanken-tai
  7. 7. Problems to use historical maps / pictorial maps (1) • Historical maps and pictorial maps contain regional attractions and are useful in tourism and education, but... • It is difficult for ordinary people with little historical knowledge to read historical maps and compare them with the current cityscape. • Conventional GIS technologies can overlap historical maps with current maps, but they distort historical maps so badly that they lose their appeal. 7
  8. 8. Problems to use historical maps / pictorial maps (2) • An example of a historical map distorted by conventional GIS technology 8
  9. 9. Maplat made it possible to overlay historical maps over accurate maps without distorting them 9
  10. 10. 10 Always align the historical map with the accurate map at the center of the display. Roughly calculate the direction and scale around the center point to make it appear that they overlap roughly as a whole.
  11. 11. A method of coordinates transformation 11
  12. 12. A method of coordinates transformation (1) Creating a triangulate network 12 Creating a triangulate network by establishing GCPs between a historical map and an accurate map.
  13. 13. A method of coordinates transformation (2) Inside of the outer packaging of the GCPs 13 Historical Map Accurate Map In the outer packaging of the GCPs, coordinates are transformed by vector calculation using triangulate network.
  14. 14. A method of coordinates transformation (3) Outside of the outer packaging of the GCPs 14 Historical Map Accurate Map Extend the triangulate network area by defining the map vertices on the accurate map side with our own equations.
  15. 15. 15 A method of coordinates transformation (4) Outside of the map envelope Historical Map Accurate Map Define triangles between the vertices of the map and the centroid of the GCPs, and transform the coordinates with the vector extension.
  16. 16. Line-to-line conversion 16 New
  17. 17. 17Problem of previous logic Historical Map Accurate Map Lines may not be converted to lines if they cross the edges of the triangulate network.
  18. 18. 18 Improvement method: Adoption of the constrained edge (1) Historical Map Accurate Map The constrained edges are always taken as the edges of a triangulate network. Constrained edge
  19. 19. 19 Improvement method: Adoption of the constrained edge (2) Historical Map Accurate Map If the constrained edges are poly lines, auxiliary GCPs are inserted automatically. Constrained edge
  20. 20. Comparison with Stroly 20
  21. 21. Stroly is similar historical map technology established since 2010 21
  22. 22. Stroly’s way of coordinates transformation 22 Historical Map Accurate Map Stroly also uses vector computation, but uses nearby 3 GCPs instead of triangulate network to select GCPs. This destroys the topology of the map.
  23. 23. Comparison with Stroly (1) Errors after bidirectional conversion 23 Conversion by Maplat Conversion by Stroly Average conversion error after bidirectional conversion (pixels) Maplat: 0.00000000018 Stroly: 11.09373539396
  24. 24. Comparison with Stroly (2) Functional comparison matrix 24 Items Stroly Maplat Ease of publication ✔:Can be published after editing ×:Manual deployment Bijective conversion × ✔:Patent pending Orient/Scale conversion ×:Bugs with mismatched scales ✔:Orient / scale are precisely converted Line-to-line conversion × ✔ Map overlay ×:Toggle only, slow ✔:Always overlaying, briskly Off-line operation × ✔:PWA capable Network environment ×:Internet operation only ✔:Can run locally or on Intranet HTML embedding ×:IFRAME Embedded Only ✔:DIV embedded, API controllable Share function ×:Map sharing only ✔:Share maps and viewpoints Mobile readiness ×:Only their own apps ✔:iOS and Android libraries available POI features ×:Show info only ✔:Move or jump to any link Open source × ✔
  25. 25. Application of Maplat 25
  26. 26. Commercial Application 26 Commercial applications are often used for tourism and are provided as native smartphone applications.
  27. 27. Educational Application 27 Using features that are more familiar than conventional GIS, it has been adopted for educational fieldworks, such as walking through the history of the city, and have shown effective educational effects. Win 3 awards from Japan MILT!
  28. 28. Summary & Proposal 28
  29. 29. Summary • By using the same method of coordinate transformation as a conventional GIS and using real-time scaling and orientation around a central point, Maplat is able to superimpose the historical map with other maps without distorting it or losing its appeal. • A similar approach is called Stroly, but because it is not based on conventional GIS technology, Maplat has an advantage in the ability to convert lines to lines, as well as in the ability to bijective conversion by maintaining topology. • Because of these features, Maplat has shown significant educational effects in the field work of history education. 29
  30. 30. Proposal • The GCP information required to operate Maplat is also important when processing historical maps using conventional GIS technology. Therefore, I have given a CC license to the configuration information of each map including Maplat's GCPs and have provided them as Open Data. • Pushing the envelop, I would like to propose a subset of Maplat's map configuration file as a metadata distribution format that include the GCPs of the historical map. • The details will be published on the Github wiki at a later date. 30
  31. 31. 31 End User: kochizufan Repository: code4nara/Maplat E-mail: kochizufan@gmail.com Presentation: http://bit.ly/maplat_icc

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