// ~/sounder/sources
Map sources
Sounder starts with a set of federal maps and has none of its own beyond that. Everything else is a source you connect. Most public maps are already published in a form it reads; the trick is knowing what to look for.
$ ls examples/ # open this page on your iPhone and tap one
- Federal land ownership (BLM)Bureau of Land Management · ArcGIS map serviceAdd to Sounder
- National Forest trailsUSDA Forest Service · ArcGIS map serviceAdd to Sounder
- USGS elevation contoursU.S. Geological Survey · ArcGIS map serviceAdd to Sounder
- USGS NAIP Plus aerial imageryU.S. Geological Survey · ArcGIS image serviceAdd to Sounder
- National Wetlands InventoryU.S. Fish & Wildlife Service · WMSAdd to Sounder
These are public-domain federal services. Each link opens Sounder and adds the layer, switched on. Nothing happens on a computer or a phone without the app.
$ cat by-address.txt
- Agency map services (ArcGIS)
- Most county, state and federal GIS offices publish this way: parcels, public land, trails, zoning, flood zones, aerials. Paste the service address into Layers, Add Layers, Add from URL. You don't need to build a tile template; Sounder asks the service what it offers.
https://…/arcgis/rest/services/…/MapServerhttps://…/arcgis/rest/services/…/ImageServerWith the layer on, tap the map to see what the service knows about that spot (a parcel's record, a trail's name). On the layer's page you can switch its sublayers on and off. - WMS
- The open standard for map servers; weather, wetlands, geology and many agencies outside the US use it. Paste the server address or a GetCapabilities link. If the server offers several layers, Sounder lists them and you pick.
https://…/WMSServerhttps://…?service=WMS&request=GetCapabilities - Tile addresses (XYZ, TMS, TileJSON)
- A web map cut into square tiles. If a website or another map app gives you a "custom map source" or a tile URL, paste it as it is, including QGIS-style
{-y}and Leaflet-style{s}addresses. A link to a TileJSON file works too.https://…/{z}/{x}/{y}.png - PMTiles on a web server
- A single-file map that can be read over the network a piece at a time. Paste the address of the
.pmtilesfile.
$ cat by-file.txt
- MBTiles and PMTiles
- A whole map in one file, raster or vector, that needs no signal. QGIS, MapTiler and tippecanoe make them, and some agencies and clubs hand them out. Get the file onto the phone (AirDrop, Files, iCloud Drive), then Layers, Add Layers, Import file. Or share the file and pick Sounder.
- GPX, KML, KMZ, GeoJSON
- Waypoints, tracks and shapes: exports from a GPS unit or another mapping app, or data an agency offers for download. When you open one, Sounder asks whether it goes into Saved as your own waypoints and tracks, or onto the map as a layer.
$ cat finding-your-county.txt
- Where is my county's map server?
- Search for the county or agency name plus
arcgis rest services. You're looking for a plain page titled "ArcGIS REST Services Directory" with a list of folders. Open folders until you reach a line ending in(MapServer)or(ImageServer), open it, and copy the address from the browser's address bar. - I only have the county's web map, not a server address.
- The web map is drawing from a server like the one above. Look for an "about", "details" or "data" link on the map, or search the county's open data site. Layers there usually list a "service URL" or "API" address.
- It says FeatureServer.
- That's the raw data, not a drawn map, and Sounder doesn't read it yet. The same agency nearly always has a MapServer beside it with the same name; use that one.
- The layer added but nothing shows.
- Zoom in. Many services only draw past a certain scale (parcels often start around the neighborhood level). Check that the layer is above your base map in Active Layers, and that you're looking at the area the agency covers. Some servers are also just slow; give it a few seconds.
- Will it work with no signal?
- Not on its own; these are live services. Before a trip, frame the area on the map, tap +, then Download area, and pick the layers to keep. Some services don't allow saving; Sounder tells you which.
$ cat catalogs.txt
- What's a catalog?
- A list of layers and offline maps that someone publishes as one link: a club, a county, a friend who has done the digging for an area. Subscribe under Layers, Add Layers, Catalogs, and its layers show up under Inactive Layers and stay current when the list changes.
- Can I publish one?
- Yes. A catalog is a small JSON file on any web server. If you've collected the good layers for your area and want to share them, write and I'll send the format.
$ cat fine-print.txt
Map services belong to the agencies that run them. They can change, slow down or go away, and what they show can be out of date or wrong: tax-roll ownership is not a survey, and a trail on a map is not permission to use it. Check posted signs and the agency's own terms before you rely on a layer.