25:["$","title",null,{"children":"Peirce quincuncial projection and great-circle path | Geolffrey Mena | Observable"}] 49:[{"id":"44e844e68240a35718846eaa5c217d541e4b6bb7245848fe5d6bb90c2cd759a804f3c56dbf681049dd53b6cb26d9911f18210beb1859ea5307fb3e087141a576","href":"https://static.observableusercontent.com/files/44e844e68240a35718846eaa5c217d541e4b6bb7245848fe5d6bb90c2cd759a804f3c56dbf681049dd53b6cb26d9911f18210beb1859ea5307fb3e087141a576","name":"world-50m.json","type":"application/json","lastModified":1683498456145.376,"size":744301},{"id":"5667cf6ea53cdbed31600d60556314bcefb28a3bbd66abb351464ab8cf0665cc3a4d508f73841f6ffa78ec215f8ee8acf29e09b8429409b30a3c7e4a18cc2f7f","href":"https://static.observableusercontent.com/files/5667cf6ea53cdbed31600d60556314bcefb28a3bbd66abb351464ab8cf0665cc3a4d508f73841f6ffa78ec215f8ee8acf29e09b8429409b30a3c7e4a18cc2f7f","name":"world-110m_withlakes.topo.json","type":"application/json","lastModified":1683498456145.376,"size":92469},{"id":"be41daaf188cea412654faf070d59c21f684d937ed804388709425dca8e6c79a0981bfa9202b3ae6ff65fc2b9ebc7ac310f00d17299a310b8354a68129f41dd3","href":"https://static.observableusercontent.com/files/be41daaf188cea412654faf070d59c21f684d937ed804388709425dca8e6c79a0981bfa9202b3ae6ff65fc2b9ebc7ac310f00d17299a310b8354a68129f41dd3","name":"great_circle.topo.json","type":"application/json","lastModified":1683498456145.376,"size":521575}] 29:{"id":"f69264ffcea65a7f","slug":null,"title":"Peirce quincuncial projection and great-circle path","thumbnail":"71835a99cdc9ad09ce769278c0c70f6b83c61c36388632bd5b2b9a673081ddb1","access_level":"public","create_time":"$D2023-05-07T22:27:36.145Z","update_time":"$D2023-05-07T22:27:36.145Z","view_time":null,"first_public_time":"$D2023-05-07T22:27:36.145Z","has_unpublished_edits":null,"fork":{"id":"44168ad6a821cd5a","slug":"peirce-quincuncial-projection-and-great-circle-path","title":"Peirce quincuncial projection and great-circle path","owner":{"id":"dd67891d326bcfb1","login":"christophe-yamahata","name":"Christophe Yamahata"}},"stars":0,"starred":false,"owner":{"type":"team","id":"512422694552d8f4","login":"geolffrey","name":"Geolffrey Mena","avatar_url":"https://avatars-next.observableusercontent.com/7ff8796d5ceeb2e688e13e7f673d5a14a89565175c45435e2ba9d1786da7e3d8","tier":"starter_2024","bio":"","followed_by_you":false,"follows_you":false},"version":377,"publish_version":null,"role":null,"authored":false,"authors":[{"type":"individual","id":"62b4da3018fa67fe","login":"geolffrey","name":"Geolffrey Mena","avatar_url":"https://avatars-next.observableusercontent.com/7ff8796d5ceeb2e688e13e7f673d5a14a89565175c45435e2ba9d1786da7e3d8","tier":null,"bio":"","followed_by_you":false,"follows_you":false}],"members":[{"type":"individual","id":"62b4da3018fa67fe","login":"geolffrey","name":"Geolffrey Mena","avatar_url":"https://avatars-next.observableusercontent.com/7ff8796d5ceeb2e688e13e7f673d5a14a89565175c45435e2ba9d1786da7e3d8","tier":null,"role":"editor"}],"comments":[],"custom_thumbnail":false,"trashed":false,"lapsed":null,"subscribed":null,"forks":0,"collection":null,"type":"notebook","body":{"titling":"auto","title":"Peirce quincuncial projection and great-circle path","cells":[{"id":0,"value":"# Peirce quincuncial projection and great-circle path","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":300,"value":"

\n The Peirce Quincuncial projection map has the interesting property that it can be tiled infinitely on the plane. \n

\n The following map shows examples of shortest distances for the travels (as the crow flies) between the following cities: Geneva, Seattle, Valparaiso, Rio de Janeiro, Madagascar, Tokyo, Shangai, Sydney.\n

\n Check the following links for inspiration and for calculations:\n

Mike Bostock’s notebook on Peirce's quincuncial projection: [@d3/peirce-quincuncial]
Great circle and shortest distance: great-circle distance

\n Check also this dynamic version of the Peirce quincuncial projection.\n

\n
","pinned":false,"hidden":false,"mode":"html","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":320,"value":"{\n const context = DOM.context2d(width, height);\n context.translate(width / 2, height / 2);\n context.scale(0.5, 0.5);\n context.globalAlpha = map_transparency;\n context.drawImage(map, 0, 0, width, height);\n context.globalAlpha = 1; \n context.drawImage(map, -width, -width, width, height);\n context.rotate(Math.PI);\n context.globalAlpha = map_transparency; \n context.drawImage(map, -width, 0, width, height);\n context.drawImage(map, 0, -width, width, height);\n \n return context.canvas;\n}","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":14,"value":"md`---\n\n## Appendix`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":170,"value":"height = 1150;\n","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":179,"value":"width = height;","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":352,"value":"map_transparency = 0.3","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":185,"value":"color_lakes = '#0ac'","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":239,"value":"color_land = \"#666\"","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":252,"value":"color_boundaries = \"#999\"","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":272,"value":"color_routes = \"#e04\"","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":18,"value":"// We don't display this map\nmap = {\n const context = DOM.context2d(width, height);\n const projection = d3.geoPeirceQuincuncial().fitSize([width, height], {type: \"Sphere\"}).precision(0.1);\n const path = d3.geoPath(projection, context);\n path.pointRadius(0.8);\n \n context.beginPath(), path(graticule), context.strokeStyle = \"#ddd\", context.stroke();\n context.beginPath(), path(land), context.fillStyle = color_land, context.fill();\n context.beginPath(), path(countries), context.strokeStyle = color_boundaries, context.stroke();\n context.beginPath(), path(add_lakes), context.fillStyle = color_lakes, context.fill();\n context.beginPath(), path(routes), context.strokeStyle = color_routes, context.point= \"1\", context.stroke();\n\t\n context.canvas.style.display=\"none\"; \n return context.canvas;\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":7,"value":"d3 = require(\"d3@5\", \"d3-geo@1\", \"d3-geo-projection@2\")","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":29,"value":"graticule = d3.geoGraticule10()","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":31,"value":"world = FileAttachment(\"world-50m.json\").json()","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":43,"value":"land = topojson.feature(world, world.objects.land)","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":249,"value":"countries = topojson.feature(world, world.objects.countries)","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":46,"value":"lakes = FileAttachment(\"world-110m_withlakes.topo.json\").json()","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":48,"value":"add_lakes = topojson.feature(lakes, lakes.objects.lakes)","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":267,"value":"routes = FileAttachment(\"great_circle.topo.json\").json()","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"}],"files":"$W49","stdlib":"1"}} 24:null