{"id":4955,"date":"2017-09-26T12:00:27","date_gmt":"2017-09-26T16:00:27","guid":{"rendered":"http:\/\/www.maproomblog.com\/?p=4955"},"modified":"2017-09-26T17:31:28","modified_gmt":"2017-09-26T21:31:28","slug":"tissots-indicatrix","status":"publish","type":"post","link":"https:\/\/www.maproomblog.com\/2017\/09\/tissots-indicatrix\/","title":{"rendered":"Tissot’s Indicatrix"},"content":{"rendered":"
\"\"<\/a>
Tissot’s indicatrices superimposed on the Robinson projection. Map by Eric Gaba. Wikimedia Commons.<\/figcaption><\/figure>\n

Geo Lounge<\/em>\u2019s Elizabeth Borneman has a piece<\/a> on\u00a0Tissot’s indicatrix<\/a>, which tends to turn up in discussions of map projections. (See, for example, this piece<\/a> from Vox’s Johnny Harris, and the accompanying video<\/a>.) And for good reason: it’s a useful visualization tool. All maps distort\u2014representing a curved surface on a flat plane, et cetera, et cetera\u2014but a grid of Tissot’s indicatrices superimposed on a world map will measure the distortion\u2014linear, angular, by area\u2014produced by that map’s projection. On the Mercator projection, the indicatrices remain perfect circles, but grow larger toward the poles; on equal-area equatorial projections, they maintain their size but squish into ellipses; on other projections they also angle left or right depending on how close they are to the edge. On compromise projections like the Robinson<\/a> (see above), they do all three.<\/p>\n","protected":false},"excerpt":{"rendered":"

Geo Lounge\u2019s Elizabeth Borneman has a piece on\u00a0Tissot’s indicatrix, which tends to turn up in discussions of map projections. (See, for example, this piece from Vox’s Johnny Harris, and the accompanying video.) And for good… More<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"link","meta":{"autoblue_enabled":true,"autoblue_custom_message":"","autoblue_shares":[],"autoblue_post_url":"","_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[29],"tags":[571,903],"class_list":["post-4955","post","type-post","status-publish","format-link","hentry","category-cartography","tag-map-projections","tag-tissots-indicatrix","post_format-post-format-link"],"jetpack_featured_media_url":"","jetpack-related-posts":[{"id":1787582,"url":"https:\/\/www.maproomblog.com\/2019\/08\/a-map-projections-roundup\/","url_meta":{"origin":4955,"position":0},"title":"A Map Projections Roundup","author":"Jonathan Crowe","date":"8 August 2019","format":"link","excerpt":"Three things make a roundup. Here we go: Here\u2019s a gallery of all 68 map projections supported in ArcGIS 10.7.1 and ArcGIS Pro 2.4, from Bojan \u0160avri\u010d and Melita Kennedy. Some interesting projections included here, some of which are only suitable for a specific region (such as the complex New\u2026","rel":"","context":"In "Cartography"","block_context":{"text":"Cartography","link":"https:\/\/www.maproomblog.com\/category\/cartography\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.maproomblog.com\/xq\/wp-content\/uploads\/2019\/08\/chris-whong-mercator-peel-1024x768.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.maproomblog.com\/xq\/wp-content\/uploads\/2019\/08\/chris-whong-mercator-peel-1024x768.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/www.maproomblog.com\/xq\/wp-content\/uploads\/2019\/08\/chris-whong-mercator-peel-1024x768.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/www.maproomblog.com\/xq\/wp-content\/uploads\/2019\/08\/chris-whong-mercator-peel-1024x768.jpg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":1789121,"url":"https:\/\/www.maproomblog.com\/2020\/08\/comparing-map-projections\/","url_meta":{"origin":4955,"position":1},"title":"Comparing Map Projections","author":"Jonathan Crowe","date":"17 August 2020","format":"link","excerpt":"Kai\u2019s Comparing Map Projections mashes up two code blocks by Mike Bostock: Map Projections Distortions is a visualization of the types of distortion inherent to each projection; Projection Transitions morphs between projections. Combining the two is a neat trick. Refreshing to see the usual two combatants excluded. [Maps Mania]","rel":"","context":"In "Cartography"","block_context":{"text":"Cartography","link":"https:\/\/www.maproomblog.com\/category\/cartography\/"},"img":{"alt_text":"Comparing Map Projections (screenshot)","src":"https:\/\/i0.wp.com\/www.maproomblog.com\/xq\/wp-content\/uploads\/2020\/08\/comparing-map-projections-1024x828.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.maproomblog.com\/xq\/wp-content\/uploads\/2020\/08\/comparing-map-projections-1024x828.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/www.maproomblog.com\/xq\/wp-content\/uploads\/2020\/08\/comparing-map-projections-1024x828.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/www.maproomblog.com\/xq\/wp-content\/uploads\/2020\/08\/comparing-map-projections-1024x828.jpg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":1790751,"url":"https:\/\/www.maproomblog.com\/2021\/05\/the-unicorn-of-map-projections\/","url_meta":{"origin":4955,"position":2},"title":"The Unicorn of Map Projections","author":"Jonathan Crowe","date":"4 May 2021","format":"link","excerpt":"It\u2019s a shame that Sarah Battersby\u2019s essay in The International Journal of Cartography, \u201cThe Unicorn of Map Projections,\u201d is behind a paywall: it looks at the recent rash of map projections that purport to solve \u201call our mapping problems.\u201d There have been more than a few that have claimed the\u2026","rel":"","context":"In "Cartography"","block_context":{"text":"Cartography","link":"https:\/\/www.maproomblog.com\/category\/cartography\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":1790076,"url":"https:\/\/www.maproomblog.com\/2021\/02\/map-projections-for-babies\/","url_meta":{"origin":4955,"position":3},"title":"Map Projections for Babies","author":"Jonathan Crowe","date":"4 February 2021","format":"link","excerpt":"Late last year\u00a0Dan Ford launched a Kickstarter to create a board book (i.e., a children\u2019s book printed on paperboard) about map projections called Map Projections for Babies. 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