Ask HN: Offline display lat long on SVG map?
It&#x27;s not entirely clear to me what you&#x27;re asking, so please excuse me if I misunderstood something (please do explain if that&#x27;s the case!).<p>If all you want is an offline map on your phone, you can already do that in Google Maps, just drag an area to download and you can position yourself using GPS and navigate around in it without needing internet. That lets you download a big area at a time (several hundred square miles). If you want something for the entire globe, you might need a different app, and it probably wouldn&#x27;t be as detailed.<p>The OpenStreetMap project has data for the whole world, to some fairly good level of detail (depending on where you are and what you need it for). The dataset comes in about 100 GB: <a href="https:&#x2F;&#x2F;wiki.openstreetmap.org&#x2F;wiki&#x2F;Downloading_data" rel="nofollow">https:&#x2F;&#x2F;wiki.openstreetmap.org&#x2F;wiki&#x2F;Downloading_data</a> and you can use one of these apps to view it: <a href="https:&#x2F;&#x2F;wiki.openstreetmap.org&#x2F;wiki&#x2F;Using_OpenStreetMap_offline" rel="nofollow">https:&#x2F;&#x2F;wiki.openstreetmap.org&#x2F;wiki&#x2F;Using_OpenStreetMap_offl...</a><p>Both Google Maps and OpenStreetMaps make extensive use of vector layers. An SVG is just one file format for storing vector shapes, but there are many others, and mapping apps usually use more specialized formats. But they are still vectors and share many of the advantages of SVG (smaller file size, cleaner lines, easier to edit, etc.) It&#x27;s not really SVG but similar enough.<p>If you&#x27;re not just wanting that for personal use and you want to MAKE such a map yourself, it gets a bit more complicated.<p>This is a helpful article on map projections, including lat long: <a href="https:&#x2F;&#x2F;www.esri.com&#x2F;arcgis-blog&#x2F;products&#x2F;arcgis-pro&#x2F;mapping&#x2F;gcs_vs_pcs&#x2F;#:~:text=What is the difference between,map or a computer screen" rel="nofollow">https:&#x2F;&#x2F;www.esri.com&#x2F;arcgis-blog&#x2F;products&#x2F;arcgis-pro&#x2F;mapping...</a>.<p>An SVG (or any other vector shape) has no innate projection, it&#x27;s just a bunch of lines and curves. You can georeference them (align a shape, like a building or lake outline) to real-world geography using GIS software, like the free and open source QGIS or paid software like ArcMap.<p>Then you&#x27;d save that into some geo-enabled format. For the web that would be something like GeoJSON or one of the ESRI web formats.<p>A geoJSON gives you vector shapes, much like SVG would, except they exist in some defined reference system of your choice (like the list here: <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;EPSG_Geodetic_Parameter_Dataset#Common_EPSG_codes" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;EPSG_Geodetic_Parameter_Datase...</a>). You can use free software like Leaflet or OpenLayers to display them on a webpage. OpenLayers is good at taking different layers of geo data and reprojecting them on the fly to whatever you want, then you can add additional base layers (OpenStreetMap, aerial photos, whatever) below your vector shapes.<p>If all of that is too complicated and you just want to make a simple map you can share with friends or whatever, maybe try Caltopo, Felt, or Google My Maps?<p>If I totally misunderstood what you&#x27;re asking, please do explain.