{"id":41,"date":"2019-07-05T07:00:00","date_gmt":"2019-07-05T07:00:00","guid":{"rendered":"http:\/\/wcwp.rf.gd\/2019\/07\/05\/https-landscapearchaeology-org-2019-shading-kickstarter\/"},"modified":"2019-07-05T07:00:00","modified_gmt":"2019-07-05T07:00:00","slug":"shading-kickstarter","status":"publish","type":"post","link":"https:\/\/landscapeanalysis.org\/?p=41","title":{"rendered":"DEM shading algorithm for QGIS"},"content":{"rendered":"<p>I\u2019ve been seeing on the net more and more of beautiful maps made in 3D software, Blender mostly. The reason for venturing into 3D: shadows mostly. While we do have hillshading algorithms in most GIS packages, nothing can beat true ambient light for terrain visualisation. Shadows do not only give a natural feel to an image, they also provide important information on object shapes and depths (see examples below).<\/p>\n<p><img decoding=\"async\" class=\"alignnone size-medium wp-image-67\" src=\"http:\/\/landscapearchaeology.org\/wp-content\/uploads\/figures-jekyll\/schema.png\" alt=\"schema.png\" \/><br \/>\n<em>The basic idea od natural shading: modelling light paths.<\/em><\/p>\n<p>How come we don\u2019t have proper shading algorithms for cartographic purposes? Don\u2019t know, but upon seeing all those ten-page tutorials for 3D software, I figured it wouldn\u2019t be more difficult to simply build the algorithm for QGIS. (Well, it turned out to be more difficult than I imagined, as usual with coding \u2026) Anyway, the algorithm is up and running in QGIS (<a href=\"https:\/\/landscapeanalysis.org\/2019\/qgis-shadows\/\">landscapeanalysis.org\/2019\/qgis-shadows\/<\/a>). But that\u2019s more of a proof of concept: I\u2019ve started a <a href=\"https:\/\/www.kickstarter.com\/projects\/archaeology\/terrain-shading-plugin-for-qgis\"><strong>Kickstarter campaign<\/strong><\/a> to develop a more robust algorithm and to integrate it in QGIS architecture (Processing toolbox). Support it and QGIS will be happy :).<\/p>\n<p>What is the difference between \u201chillshading\u201d and \u201cnatural shading\u201d? (Neither of the terms is ideal\u2026) <strong>Hillshade algorithms<\/strong>, as implemented in most GIS, model <strong>light reflectance<\/strong>, that is, the way light rays should bounce off a smooth surface. <strong>Natural shading<\/strong>, on the other hand, models <strong>unreflected light path<\/strong>, namely shadows which are produced in areas inaccessible to light from a particular light source. Therefore, true shading can be produced by <strong>combining the two: hillshade + natural shadows<\/strong>.<\/p>\n<h2 id=\"shaded-terrain-examples\">Shaded terrain examples<\/h2>\n<p><iframe loading=\"lazy\" frameborder=\"0\" class=\"juxtapose\" width=\"100%\" height=\"620\" src=\"https:\/\/cdn.knightlab.com\/libs\/juxtapose\/latest\/embed\/index.html?uid=455cca0e-9f05-11e9-b9b8-0edaf8f81e27\"><\/iframe><\/p>\n<p><em>Coast of Dalmatia, Croatia.<\/em><\/p>\n<p><iframe loading=\"lazy\" frameborder=\"0\" class=\"juxtapose\" width=\"100%\" height=\"566\" src=\"https:\/\/cdn.knightlab.com\/libs\/juxtapose\/latest\/embed\/index.html?uid=9c44cc92-9ffd-11e9-b9b8-0edaf8f81e27\"><\/iframe><\/p>\n<p><em>Gergovia stronghold (France): Caesar\u2019s army was defeated there (or at least retreated without seizing the Gaulish fortress\u2026). Data: Lidar scan, www.craig.fr. Map: Elise Fovet, MSH Clermont-Ferrand.<\/em><\/p>\n<p><iframe loading=\"lazy\" frameborder=\"0\" class=\"juxtapose\" width=\"100%\" height=\"694\" src=\"https:\/\/cdn.knightlab.com\/libs\/juxtapose\/latest\/embed\/index.html?uid=438272fe-a001-11e9-b9b8-0edaf8f81e27\"><\/iframe><\/p>\n<p><em>Gergovia : detail of suface structures (modern period drystone walls and cairns, which may sometimes cover archaeological remains). Data: Lidar scan, www.craig.fr. Map: Elise Fovet, MSH Clermont-Ferrand.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"<p>I\u2019ve been seeing on the net more and more of beautiful maps made in 3D software, Blender mostly. The reason for venturing into 3D: shadows mostly. While we do have hillshading algorithms in most GIS packages, nothing can beat true ambient light for terrain visualisation. Shadows do not only give a natural feel to an [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[11],"class_list":["post-41","post","type-post","status-publish","format-standard","hentry","category-qgis-plugins","tag-qgis"],"_links":{"self":[{"href":"https:\/\/landscapeanalysis.org\/index.php?rest_route=\/wp\/v2\/posts\/41","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/landscapeanalysis.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/landscapeanalysis.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/landscapeanalysis.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/landscapeanalysis.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=41"}],"version-history":[{"count":0,"href":"https:\/\/landscapeanalysis.org\/index.php?rest_route=\/wp\/v2\/posts\/41\/revisions"}],"wp:attachment":[{"href":"https:\/\/landscapeanalysis.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=41"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/landscapeanalysis.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=41"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/landscapeanalysis.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=41"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}