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AuthaGraph projection
AuthaGraph projection
AuthaGraph projection
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An approximation of the AuthaGraph projection

AuthaGraph is an approximately equal-area world map projection invented by Japanese architect Hajime Narukawa[1] in 1999.[2] The map is made by equally dividing a spherical surface into 96 triangles, transferring it to a tetrahedron while maintaining area proportions, and unfolding it in the form of a rectangle: it is a polyhedral map projection. The map substantially preserves sizes and shapes of all continents and oceans while it reduces distortions of their shapes, as inspired by the Dymaxion map. The projection does not have some of the major distortions of the Mercator projection, like the expansion of countries in far northern latitudes, and allows for Antarctica to be displayed accurately and in whole.[3] Triangular world maps are also possible using the same method. The name is derived from "authalic" and "graph".[3]

The method used to construct the projection ensures that the 96 regions of the sphere that are used to define the projection each have the correct area, but the projection does not qualify as equal-area because the method does not control area at infinitesimal scales or even within those regions.

The AuthaGraph world map can be tiled in any direction without visible seams. From this map-tiling, a new world map with triangular, rectangular or a parallelogram's outline can be framed with various regions at its center. This tessellation allows for depicting temporal themes, such as a satellite's long-term movement around the Earth in a continuous line.[4]

In 2011 the AuthaGraph mapping projection was selected by the Japanese National Museum of Emerging Science and Innovation (Miraikan) as its official mapping tool.[5] In October 2016, the AuthaGraph mapping projection won the 2016 Good Design Grand Award from the Japan Institute of Design Promotion.[6]

On April 16, 2024, Nebraska Governor Jim Pillen signed a law that requires public schools to use only maps based on the Gall–Peters projection, a similar cylindrical equal-area projection, or the AuthaGraph projection, beginning in the 2024–2025 school year.[7][8][9]

See also

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References

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Revisions and contributorsEdit on WikipediaRead on Wikipedia

AuthaGraph projection

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from Grokipedia
The AuthaGraph projection is an approximately equal-area projection invented by Japanese architect Hajime Narukawa in 1999. It transforms the spherical surface of the into a rectangular format by first dividing the globe into 96 equal-area triangles, projecting these onto a , and then unfolding the into a plane using techniques such as iso-area-mapping and multilayer-mapping to minimize distortions in both area and shape. This method preserves the relative sizes of continents and oceans, including a faithful representation of often neglected in traditional projections, while maintaining continuous networks of landmasses and seas without interruptions or fragmentation. Unlike conventional projections such as the Mercator, which severely distort polar regions and high-latitude areas, the AuthaGraph design allows for seamless tiling in multiple directions and reconfiguration by sliding or rotating the frame to center any geographic region, providing flexible perspectives on global geography. These properties stem from its foundation in geometric subdivision and intermediate polyhedral stages, which reduce the tearing and stretching inherent in direct spherical-to-planar mappings. The projection has been recognized for its innovative approach to cartographic accuracy, winning the 2016 Good Design Grand Award from the Institute of Design Promotion for effectively balancing representational fidelity with practical usability in rectangular formats. It has been adopted as an official mapping tool by the Miraikan National Museum of Emerging and Innovation in and incorporated into Japanese high textbooks, highlighting its utility in educational and scientific contexts.

History and Development

Invention by Hajime Narukawa

Hajime Narukawa, a Japanese architect born in 1971, invented the AuthaGraph projection in 1999 as an equal-area world map projection aimed at preserving the relative sizes of continents and oceans on a flat surface. The method involves dividing the spherical Earth into 96 equal-area triangles before unfolding and projecting them onto a rectangle, seeking to reduce the distortions inherent in conventional projections like the Mercator. Narukawa's invention addressed longstanding challenges in cartography by prioritizing area accuracy over shape fidelity in certain regions, allowing for a more balanced representation that includes underrepresented areas such as and the polar regions. This approach emerged from his architectural background, where spatial representation and proportion are critical, leading him to develop a projection that could be reoriented and tiled without significant loss of informational integrity. In , Narukawa established AuthaGraph Co., Ltd., to refine and commercialize the projection, marking a transition from conceptual invention to practical application in and . The core innovation lies in its geometric flexibility, enabling multiple viewing perspectives while maintaining equal-area properties, which distinguishes it from rigid traditional mappings.

Key Milestones and Awards

The AuthaGraph projection was invented in 1999 by Japanese architect Hajime Narukawa through a process involving the subdivision of the globe's surface into 96 equal-area triangles, followed by reconfiguration onto a and subsequent unfolding into a . Narukawa first publicly released the AuthaGraph in 2010, introducing it as a rectangular projection designed to minimize distortions in area, , and connectivity compared to traditional maps like the Mercator. In October 2016, the AuthaGraph World Map received the Good Design Grand Award, the highest honor from the Institute of Design Promotion, recognizing its innovative approach to equal-area representation and potential to reshape perceptions of global geography.

Technical Construction

Geometric Division Process

The geometric division process of the AuthaGraph projection initiates with the of the Earth's spherical surface into 96 triangles of approximately equal area. This subdivision employs a , where the sphere is partitioned using intersecting lines to form triangular facets that collectively cover the entire globe without overlap or gap. The choice of 96 triangles balances computational feasibility with representational fidelity, enabling the capture of continental and oceanic proportions at a resolution sufficient to minimize local distortions in area during later stages. Each triangular region is defined such that its spherical excess—arising from the —contributes equally to the total surface area, which is then preserved through conformal mapping techniques onto intermediate polyhedral surfaces. This initial division draws from principles of akin to those in icosahedral projections but adapted for tetrahedral unfolding, ensuring that the resulting facets can be rigidly transferred while upholding the projection's equal-area criterion. The process, developed by Narukawa since 1999, avoids arbitrary cutting lines by relying on symmetric partitioning, which supports the map's reorientability and tiling properties.

Unfolding and Projection Mechanics

The AuthaGraph projection constructs a through a transformation process that begins with the equal subdivision of the Earth's spherical surface into 96 triangular regions, each preserving the original area proportions of land and water. These triangles are then transferred onto the faces of a —a four-sided —via a mapping that maintains equal-area properties by adjusting for spherical onto the polyhedral . This transfer involves initially projecting the triangles onto an inflated to accommodate the globe's excess surface area beyond the polyhedron's geometry, followed by a normalization step that flattens it into a regular without altering relative sizes. The resulting tetrahedral is cut along optimized edges to minimize discontinuities, particularly across polar and equatorial zones, and unfolded into a planar net. Multiple such nets are aligned and sheared to form a continuous with a 3:4 , enabling seamless tiling for global representations. The unfolding mechanics prioritize reducing shape distortions by strategically positioning cuts that avoid severing major landmasses or ocean basins, allowing interconnected regions like and the Pacific to appear contiguous. Unlike cylindrical projections, which stretch high latitudes, this polyhedral unfolding distributes distortions more evenly, though local angular inaccuracies persist near vertices due to the inherent incompatibility between spherical and planar topologies. The process supports reorientation by varying cut lines, permitting alternative viewpoints without recalculating the base projection.

Properties and Characteristics

Area Preservation and Distortions

The AuthaGraph projection is an approximately equal-area world map projection, intended to maintain the relative sizes of landmasses and oceans as on the globe. It employs a technique known as iso-area-mapping, dividing the spherical surface into 96 triangular regions of equal area before projecting them onto a tetrahedron and unfolding into a rectangle, thereby minimizing discrepancies in continental and oceanic proportions compared to traditional projections. However, it is not strictly equal-area; for instance, Russia appears more than twice the size of China on the map, whereas Russia's land area of approximately 17 million km² is less than twice China's 9.6 million km², indicating residual area inaccuracies. To achieve this level of area fidelity, the projection introduces distortions in shapes and angles. Landmasses exhibit altered geometries, with shapes somewhat compromised, particularly near the poles and map edges where the unfolding process stretches or compresses features. The graticule's angles are severely distorted in regions such as , rendering the non-conformal and unsuitable for applications requiring angle preservation, like . Lines of constant bearing do not map to straight lines or simple curves, further complicating distance and direction representations. These trade-offs reflect the inherent challenges of projecting a three-dimensional onto a two-dimensional surface, where perfect preservation of both area and is impossible per the principles of cartographic projection . The AuthaGraph prioritizes area accuracy over integrity, resulting in a representation that better conveys global proportional extents but at the cost of familiar continental outlines.

Shape, Distance, and Direction Fidelity

The AuthaGraph projection reduces shape distortions of continents and oceans compared to traditional cylindrical projections, drawing inspiration from the Dymaxion map's approach while employing a tetrahedral unfolding of 96 spherical triangles. Its average angular distortion index measures 0.265, outperforming the (0.594) and Winkel Tripel (0.415) in this metric, achieved via a power function that inflates vertex regions and confines distortions primarily to oceans and . Despite these improvements, the projection remains non-conformal, failing to preserve local shapes and angles exactly, with heavier distortions near singularities and polar representations. Distance fidelity in AuthaGraph is not maintained equidistantly; a power curve with an exponent of 0.68 repositions points to prioritize angular accuracy over linear distances, resulting in variable scale distortions averaging 0.399—higher than the Winkel Tripel's 0.231. This even distribution of distance errors, rather than concentration along axes, enhances overall representational balance but introduces inaccuracies, particularly in stretched regions away from the tetrahedron's faces. Direction preservation is approximate, supported by the projection's low angular distortion but compromised by its non-conformal properties, which alter local orientations and bearings relative to the . By eschewing latitude-longitude axes in favor of a curved regular , AuthaGraph improves polar visibility and global continuity at the cost of precise directional fidelity in individual locales.

Advantages and Innovations

Improved Global Representation

The AuthaGraph projection improves global representation by encompassing all oceans, continents, and in a single, uninterrupted rectangular frame, addressing omissions and distortions common in conventional maps. This approach ensures no regions are severed or marginalized, providing a comprehensive view of Earth's surface. Central to its enhanced fidelity is the preservation of relative areas across landmasses and water bodies, functioning as an approximately that mitigates the extreme size exaggerations seen in Mercator maps, particularly at high latitudes where and appear disproportionately large. By dividing the globe into 96 equal triangles and mapping them onto a before unfolding, the projection substantially maintains both area proportions and shapes, drawing inspiration from polyhedral techniques to reduce overall deformation. This method yields a more equitable portrayal of global geography, enabling viewers to perceive intercontinental relationships and oceanic expanses with greater accuracy than cylindrical projections, which prioritize navigational utility over proportional integrity. For instance, and retain their true relative scales without the polar amplification that plagues Mercator renditions, fostering a balanced perspective on terrestrial distributions. While not devoid of minor distortions inherent to flattening a , AuthaGraph's design prioritizes holistic representation, making it suitable for educational and analytical purposes where unbiased is paramount.

Tiling and Reorientation Capabilities

The AuthaGraph projection enables seamless tiling of multiple instances in any direction, producing no visible seams, gaps, or overlaps at boundaries, which simulates a continuous, infinite representation of the Earth's surface. This property arises from the projection's geometric foundation, involving the division of the sphere into 96 equal-area triangles that are mapped onto a and subsequently unfolded into a , ensuring periodic compatibility across edges. Through this tiling mechanism, custom world maps can be derived by framing subsets of the tiled array, yielding outlines such as triangles or rectangles tailored to specific applications, while maintaining area proportions and inter-regional connectivity. The reorientation capability leverages seamless tiling to reposition any terrestrial region at the map's center without introducing additional distortions or discontinuities, allowing flexible centering on diverse locales such as polar areas or non-traditional hemispheres. This contrasts with fixed-orientation projections like Mercator, where preclude such adjustments without compromising fidelity.

Criticisms and Limitations

Technical Shortcomings

The AuthaGraph projection, derived from dividing the sphere into 96 equal triangles and unfolding them via a intermediate, introduces discontinuities through its inherent cuts and rearrangements, which fragment the continuous spherical surface into a planar representation with seams that, while minimized for , disrupt continuity across polar and equatorial transitions. These interruptions prevent the map from serving as a seamless tool, as meridians and parallels do not form simple straight or rhumb lines, complicating bearing calculations and rendering compass-based routing unreliable without auxiliary grids. Although designed for approximate area preservation, the projection exhibits measurable distortions in relative sizes and shapes; for example, is depicted as more than twice China's area, exceeding the actual ratio where spans about 17.1 million km² compared to China's 9.6 million km². Angular fidelity is similarly compromised, with severe shape deformations evident around regions like , where local geometries are stretched or sheared, prioritizing global area balance over conformal properties. This trade-off aligns with broader projection theory limitations, where no single map can simultaneously preserve area, , scale, and without compromise, but AuthaGraph's discrete triangular amplifies local inaccuracies compared to smoother equal-area alternatives like the . Computationally, the method relies on iterative optimization for triangle positioning during unfolding—often involving force-directed algorithms or spring embeddings—rather than a closed-form mathematical formula, resulting in non-deterministic outputs dependent on initial conditions and parameters, which hinders precise and integration into standard GIS software. Reverse-engineering efforts reveal that the core projection approximates a cylindrical equal-area base before layout adjustment, inheriting flaws like meridional convergence issues while adding complexity without eliminating fundamental spherical-to-planar distortions.

Practical and Aesthetic Drawbacks

The AuthaGraph projection's unconventional layout, which repositions continents and orients them away from traditional cardinal alignments, renders the map visually disorienting for users accustomed to rectangular formats like the Mercator, with features such as a tilted and fragmented contributing to an aesthetically fragmented appearance. This irregular, non-grid-based design sacrifices familiar geographic continuity, making landmasses appear "wonky" or disproportionately stretched, as seen in South America's exaggerated width despite equal-area intent. Practically, the projection distorts angles severely in regions like , rendering it non-conformal and unsuitable for tasks requiring shape fidelity, such as precise boundary delineation or visual comparison of forms. lines curve irregularly rather than forming a tidy grid, complicating coordinate-based , direction-finding, and use, as lines of constant bearing do not map to straight paths. Unprojecting coordinates back to standard latitude-longitude involves steep discontinuities, hindering integration with geospatial software or traditional datasets. Further practical limitations arise from its : the multi-step geometric division and unfolding demands specialized , limiting without tools, while the need for additional subdivisions to achieve precise equal-area representation adds layers of refinement not inherent to simpler projections. This unfamiliarity and repositioning of continents, such as elongating east-west beyond intuitive scales, impede widespread adoption for education, policy, or reference, as users must relearn spatial relationships rather than leveraging ingrained Mercator familiarity.

Comparisons with Other Projections

Relation to Cylindrical and Equal-Area Types

The AuthaGraph projection differs fundamentally from projections, which map the spherical surface onto a developable tangent or secant to the , resulting in straight, equidistant meridians and parallels that often introduce severe distortions in high latitudes. Cylindrical projections like the Mercator preserve angles for navigation but exaggerate polar regions' areas exponentially, while equal-area variants such as the Gall-Peters or Behrmann compensate by stretching shapes vertically to maintain relative landmass sizes, yielding elongated, ribbon-like continents. In contrast, AuthaGraph employs a polyhedral method, subdividing the into 96 equal-area spherical triangles, mapping them onto a tetrahedron's faces, and unfolding into a , which avoids the cylindrical framework's inherent shearing and enables more flexible rearrangement of continents to reduce shape distortion. As an equal-area type, AuthaGraph prioritizes preserving the proportional sizes of landmasses and oceans, akin to cylindrical equal-area projections, but achieves this approximately rather than exactly, with minor deviations to optimize overall fidelity. Traditional cylindrical equal-area maps enforce a fixed rectangular grid that compresses equatorial widths and expands polar heights uniformly, leading to unavoidable trade-offs in angular accuracy; AuthaGraph's tetrahedral intermediate allows dynamic partitioning and reorientation, partitioning the surface to balance area integrity with improved representation of inter-continental connections, such as linking , , and without artificial separation. This approach mitigates the "tall and skinny" artifacts common in cylindrical equal-area maps, where, for instance, appears disproportionately stretched compared to despite equal areas. While not deriving from cylindrical geometry, AuthaGraph's final rectangular output superficially resembles cylindrical projections' , facilitating comparison and integration into standard mapping software, though its non-conformal nature and tessellability distinguish it by permitting seamless global tiling without seams or gaps—properties absent in rigid cylindrical unfoldings. Efforts to replicate AuthaGraph's visual style with true equal-area cylindrical bases, such as adaptations using pseudo-cylindrical intermediates, underscore its influence on rethinking area-preserving designs beyond traditional cylindrical constraints.

Specific Contrasts with Mercator and Gall-Peters

The AuthaGraph projection contrasts with the Mercator projection in its prioritization of balanced distortions over strict conformality. The Mercator projection, formulated in 1569, maintains local angles and shapes for navigational utility but introduces severe areal inflation toward the poles, rendering Greenland approximately fourteen times larger in appearance than its actual size relative to Africa. In comparison, AuthaGraph divides the spherical surface into 96 triangular facets, projects them onto a tetrahedron, and unfolds into a rectangle, substantially reducing such size exaggerations while preserving relative continental proportions more accurately than Mercator's cylindrical framework. This approach sacrifices Mercator's angle preservation, rendering AuthaGraph less suitable for precise bearing calculations but superior for visualizing global scale hierarchies. Relative to the , AuthaGraph offers enhanced shape fidelity alongside approximate area conservation. The , originally described by in 1855 and revived by Arno Peters in 1973, enforces exact equal-area representation in a cylindrical format but continental outlines dramatically, elongating landmasses vertically near the and compressing them horizontally at higher latitudes, which compromises perceptual accuracy of forms like Africa's outline. AuthaGraph mitigates these trade-offs through its polyhedral reconfiguration, yielding landforms with reduced stretching and improved adjacency preservation—such as uninterrupted Pacific connections—while nearing equal-area results without the rigid cylindrical grid's shape penalties. Unlike ' fixed distortion profile, AuthaGraph's reorientable unfolding allows adaptive views that minimize edge-induced anomalies, though it remains non-equal-area in strict mathematical terms, prioritizing minimized overall deviation over perfect areal equivalence. Both Mercator and Gall–Peters adhere to cylindrical geometries that inherently favor equatorial centrality and interrupt polar or oceanic continuity, whereas AuthaGraph's tetrahedral base enables tessellated, gapless representations that better accommodate the sphere's , reducing the perceptual biases embedded in traditional projections' linear meridians and parallels. This structural innovation positions AuthaGraph as a compromise, trading some navigational precision (versus Mercator) and exact area metrics (versus Gall–Peters) for holistic fidelity in size, contiguity, and minimalized form alteration.

Reception and Applications

Awards, Media Coverage, and Adoption

In 2016, the AuthaGraph projection received the Good Design Grand Award from the Institute of Design Promotion, recognizing its innovative approach to minimizing in world mapping. This accolade highlighted its ability to represent relative sizes of landmasses and oceans more faithfully than traditional projections like Mercator, while allowing for and reorientation. Following the award, the projection garnered significant media attention, with features in outlets such as Discover Magazine, which described it as "the most accurate world map" for preserving proportions without extreme distortions. Coverage also appeared in Architectural Digest and New Atlas, emphasizing its tetrahedral unfolding method derived from dividing the globe into 80 equal parts. Japanese media, including The Japan Times, had earlier noted Hajime Narukawa's work on distortion reduction dating back to 2011. Adoption has been limited primarily to educational and artistic contexts rather than widespread cartographic or navigational use. Physical maps and globes using AuthaGraph are available for purchase via the official website, targeting users interested in alternative global views. Some U.S. educational programs, such as those under Educational Service Unit 4, incorporate it alongside equal-area projections for teaching. However, it lacks integration into major GIS software like , where its irregular geometry complicates practical applications such as distance calculations or standard mapping workflows.

Influence on Cartography and Broader Impact

The has prompted discussions within communities about the potential of polyhedral and tessellable designs to reduce distortions in area, , and continuity, offering a reorientable framework that treats no as peripheral. Despite this, it has not supplanted established projections in professional or navigational , where cylindrical types prevail for their directional accuracy and computational simplicity, limiting its integration into standard GIS software or atlases as of 2024. Its 2016 Good Design Grand Award from the Japan Institute of Design Promotion elevated its profile, recognizing the method's geometric innovation in dividing the sphere into 96 triangles for tetrahedral transfer, which preserves proportional land-ocean ratios better than many alternatives. This accolade spurred media coverage in outlets like Discover Magazine, framing it as a tool to visualize underrepresented equatorial landmasses, such as Africa's true scale relative to Greenland. Beyond , AuthaGraph has influenced educational exhibits and design applications, including 2009 installations at Japan's National Museum of Emerging Science and Innovation that extended its principles to and visualizations. It has also informed policy discussions on map equity, as noted in U.S. legislative reviews of educational materials aiming to counter area biases in traditional projections. Overall, its broader impact lies in fostering public awareness of projection trade-offs, though practical constraints like non-standard orientation hinder widespread use in global data visualization.

References

  1. https://narukawa-lab.jp/archives/authagraph-map/
  2. http://www.authagraph.com/projects/description/%E3%80%90%E4%BD%9C%E5%93%81%E8%A7%A3%E8%AA%AC%E3%80%91%E8%A8%98%E4%BA%8B01/?lang=en
  3. https://www.g-mark.org/en/gallery/winners/9dd869db-803d-11ed-af7e-0242ac130002
  4. https://support.esri.com/en-us/gis-dictionary/authagraph-projection
  5. http://www.authagraph.com/projects/description/%25E3%2580%2590%25E4%25BD%259C%25E5%2593%2581%25E8%25A7%25A3%25E8%25AA%25AC%25E3%2580%2591%25E8%25A8%2598%25E4%25BA%258B01/?lang=en
  6. http://www.authagraph.com/top/?lang=en
  7. https://decolonialatlas.wordpress.com/2017/03/11/authagraph-world-maps/
  8. https://spoon-tamago.com/hajime-narukawa-authagraph/
  9. https://www.treehugger.com/authagraph-world-map-design-4868732
  10. https://www.maproomblog.com/2016/11/authagraph-world-map-wins-japanese-design-award/
  11. https://www.dezeen.com/2017/01/13/accurate-world-map-scoops-grand-prize-at-this-years-good-design-awards/
  12. https://www.designboom.com/design/good-design-grand-award-authagraph-hajime-narukawa-11-01-2016/
  13. https://newatlas.com/authagraph-world-map-projection/46281/
  14. https://www.sciencealert.com/world-map-authagraph-origami-globe-hajime-narukawa
  15. https://www.wired.com/2016/11/weird-globe-folding-map-isnt-perfect-close/
  16. https://gis.stackexchange.com/questions/217071/what-are-the-main-drawbacks-of-the-authagraph-projection
  17. https://kunimune.blog/2017/11/23/the-secrets-of-the-authagraph-revealed/
  18. https://www.jstage.jst.go.jp/article/jjca/60/1/60_1/_article/-char/en
  19. http://www.authagraph.com/projects/authagraph-world-map/?lang=en
  20. https://www.gov-online.go.jp/eng/publicity/book/hlj/html/201204/201204_10.html
  21. https://blog.map-projections.net/an-equal-area-projection-in-the-fashion-of-the-authagraph-map
  22. https://interestingengineering.com/innovation/not-new-earth-authagraph-map-accurate-real-view
  23. https://blog.geogarage.com/2016/11/japans-good-design-award-goes-to-this.html
  24. https://dmswart.com/2016/11/10/authagraph-world-map/
  25. https://thegeopolity.com/2021/12/01/the-problem-with-maps/
  26. https://neacsu.net/geodesy/snyder/3-cylindrical/single/
  27. https://pro.arcgis.com/en/pro-app/latest/help/mapping/properties/cylindrical-equal-area.htm
  28. https://www.visualcapitalist.com/problem-with-our-maps/
  29. https://www.reddit.com/r/geography/comments/1d07407/is_the_mercator_projection_map_better_for/
  30. https://futuremaps.com/blogs/news/top-10-world-map-projections
  31. https://devwall.medium.com/different-types-of-world-map-projections-f54abb3ea904
  32. https://www.newatlas.com/authagraph-world-map-projection/46281/
  33. https://www.discovermagazine.com/finally-a-world-map-that-doesnt-lie-13
  34. https://www.architecturaldigest.com/story/accurate-map-authagraph
  35. https://www.japantimes.co.jp/life/2011/07/17/general/the-world-according-to-authagraph/
  36. https://www.esu4.org/6042
  37. https://community.esri.com/t5/coordinate-reference-systems-questions/when-will-the-authagraph-projection-be-supported/td-p/869853
  38. https://www.ntticc.or.jp/Archive/2009/Openspace2009/Works/authagraph.html
  39. https://nebraskalegislature.gov/pdf/reports/research/snapshot_worldview.pdf
  40. https://www.popsci.com/annoying-persistence-bad-maps/
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