{"id":3861,"date":"2022-11-03T22:23:17","date_gmt":"2022-11-03T09:23:17","guid":{"rendered":"http:\/\/blogs.lincoln.ac.nz\/gis\/?p=3861"},"modified":"2023-03-30T04:29:12","modified_gmt":"2023-03-30T04:29:12","slug":"submitted-for-your-reference","status":"publish","type":"post","link":"https:\/\/blogs.lincoln.ac.nz\/gis\/submitted-for-your-reference\/","title":{"rendered":"Submitted for Your Reference"},"content":{"rendered":"

Setting the reference scale for you maps can make symbology more consistent across scales.<\/em><\/p>\n

Here at GIS Central we’ve been gearing up for some work on Lake Heron Station in near Mt Somers:<\/p>\n

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As a start I thought I would pull together some of the already available data for this project, things like the LCDB, elevation, hillshades, stream networks, etc.\u00a0 Amongst the things I thought might be useful were the elevation contours, so using a provided layer of the station boundary, I started by clipping out the 20 m contours from J:\\Data\\Contours\\SouthIslandContours20m.shp.\u00a0 Next, I wanted to put a bit of effort into labelling the contours to match how they are shown on the 1:50,000 scale topomaps – we did this once before to show how\u00a0to perfect the labels using masking and annotations<\/a>.\u00a0 With about 20 minutes worth of work I was pretty happy with my results:<\/p>\n

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(Also used that trick of Graduated Symbols with rivers layer stream orders<\/a>.)\u00a0 So far so good – until I zoomed out to the full extent of the station:<\/p>\n

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What looked nice\u00a0at 1:10,000 is now overwhelmed by my contours and rivers at 1:100,000.\u00a0 The problem here is that when I set the thickness for my lines, it draws them at that same thickness regardless of the scale, with the effect we see above.\u00a0 In the deep, dark recesses of my mind, a solution sort of presented itself.\u00a0 I stumbled on to this when looking at my contour layer’s properties, more specifically on the Display tab:<\/p>\n

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I’ve often seen this thing about reference scales but to be honest, have never known what it’s all about, but it did get me thinking.\u00a0 After a bit of digging, I realised that one can set a reference scale<\/a> for a map which forces the symbol size\u00a0at be fixed to that particular scale.\u00a0 Then when you zoom in or out, the size changes to fit.\u00a0 For my purposes, 1:10,000 seemed about right, so from the Map Properties > General, this was set at 1:10,000 (you might want a different scale for your map – it could be a custom scale or one of the preset options):<\/p>\n

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(Keep in mind – this is for the map<\/em><\/strong>, not the individual layers.)\u00a0 Now I can go back to each layer and set it to honour the reference scale\u00a0once it’s been set:<\/p>\n

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After\u00a0ticking\u00a0this for my contours and rivers layer, I get a much better effect:<\/p>\n

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My contours and rivers are still there, but their thickness now changes as the map scale changes.\u00a0 Compared to the station map above, I think this displays much better.\u00a0 I’ve always wondered what the reference scales stuff was all about, and now I know.\u00a0 There’s always something new to learn with GIS.<\/p>\n

C<\/p>\n","protected":false},"excerpt":{"rendered":"

Setting the reference scale for you maps can make symbology more consistent across scales. Here at GIS Central we’ve been gearing up for some work on Lake Heron Station in near Mt Somers: As a start I thought I would pull together some of the already available data for this project, things like the LCDB, […]<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-3861","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/blogs.lincoln.ac.nz\/gis\/wp-json\/wp\/v2\/posts\/3861","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.lincoln.ac.nz\/gis\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.lincoln.ac.nz\/gis\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.lincoln.ac.nz\/gis\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.lincoln.ac.nz\/gis\/wp-json\/wp\/v2\/comments?post=3861"}],"version-history":[{"count":2,"href":"https:\/\/blogs.lincoln.ac.nz\/gis\/wp-json\/wp\/v2\/posts\/3861\/revisions"}],"predecessor-version":[{"id":3976,"href":"https:\/\/blogs.lincoln.ac.nz\/gis\/wp-json\/wp\/v2\/posts\/3861\/revisions\/3976"}],"wp:attachment":[{"href":"https:\/\/blogs.lincoln.ac.nz\/gis\/wp-json\/wp\/v2\/media?parent=3861"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.lincoln.ac.nz\/gis\/wp-json\/wp\/v2\/categories?post=3861"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.lincoln.ac.nz\/gis\/wp-json\/wp\/v2\/tags?post=3861"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}