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User guide

Screen layout

  • Top bar: Draw line / cancel, Go to coordinates (target), Zoom out, Zoom in
  • Map: OpenStreetMap raster tiles, roads, existing coloured straight segments; red denotes the selected line and blue indicates other saved lines
  • Left panel: saved line list, edit and delete actions, selected line detail, CSV/JSON export
  • Lower map bar: attribution, coordinate reference system and live pointer latitude/longitude (when drawing)

Navigate

With Draw line OFF, pan the map with the primary mouse button and zoom with the wheel or the header +/- controls. Use the target icon to centre on known decimal latitude/longitude. Map source tile zoom is limited to level 19. The initial centre is on the Isle of Man; you can navigate anywhere supported by the map service.

Draw a line (two options)

Option 1: two clicks

  1. Zoom as far as useful to locate the start position precisely.
  2. Click Draw line.
  3. Click the start location. A blue start dot appears, with a provisional orange line to the pointer.
  4. Click the end location. The Save line dialog opens.
  5. Enter a label; adjust start/end coordinates if necessary. Click Save line.

Option 2: drag

  1. Click Draw line.
  2. Press on the start location, drag at least five screen pixels to the endpoint, then release.
  3. Label, optionally edit coordinates, and save.

During drawing, pointer events go to a transparent overlay, so ordinary dragging does not pan the map. Use the header +/- to zoom while drawing. Press Esc or click Cancel drawing to abandon the unfinished line.

High-precision selection

  • Zoom to level 18–19 to minimise the ground distance represented by each screen pixel.
  • The pointer location display during drawing is decimal latitude, longitude.
  • Coordinate values in the Save/Edit dialog have nine decimal places; edit them directly for exact numeric placement.
  • Coordinates may be entered with a leading minus sign. West longitude is negative. Isle of Man longitude is approximately -4.x.
  • Latitude must be within ±85.05112878° because this map uses Web Mercator, and longitude is within ±180°.
  • An error message will prevent blank labels, identical endpoints, malformed/non-finite coordinates, and out-of-bounds values.

Important: The app does not use a GNSS receiver, cadastral dataset or surveying hardware. Numeric precision should not be mistaken for actual physical/survey accuracy. Line length is an approximate spherical straight-line distance, not route distance.

Manage and inspect lines

Click any saved line to highlight it in orange/red, centre the map on it, and reveal S (start) and E (end) markers. The panel shows start and end latitude/longitude and straight-line length. The coordinate text is selectable for copying.

Click Edit to rename the line or correct either coordinate. Click Delete and confirm to remove a line. A unique ID is retained across edits. Changes automatically update local persistent storage.

Export all lines

Click Export CSV or Export JSON. Enter a filename in the GNOME Save dialog. The exported file contains all currently saved lines, not only the selected line. The export filename is your choice; sensible defaults are gps-lines.csv and gps-lines.json.

See Data Format for CSV column names, WGS84 reference system and JSON structure.

Persistence and backup

The application automatically saves in:

~/.local/share/gps-line-studio/lines.json

Or under $XDG_DATA_HOME/gps-line-studio/lines.json if the variable is set. It does not share this information with OSM: only tile requests are sent over the network. Before replacing your computer or reinstalling Fedora, copy the file or export to JSON/CSV.

Limitations

  • Lines are direct two-point segments, not OSM road-following routes.
  • No import, snapping, waypoint routing, measurement certification or live GPS receiver support in v0.1.
  • The map needs online access for noncached tiles; do not use the public OSM server as an offline-tile download service.
  • For very long international lines crossing the antimeridian, midpoint/visual line behaviour is optimised for short, local segments.