Preferences
File → Preferences… opens a small settings dialog. Values are persisted with QSettings (under organisation InteractiveGMT, application i'GMT) and reloaded every session, so a choice made once survives restarts. Settings apply to newly created objects / subsequent actions — existing objects are not retro-changed (use Line Properties for per-object overrides).
The OK button is the only control that writes the settings; editing a combo box does not commit anything until you press OK.
Default directory
The folder every file Open / Save dialog starts in. It is the head of a most-recently-used (MRU) list: after you pick a file anywhere, that file's folder becomes the new default and joins the list (deduplicated, capped at 12 entries). The combo offers the whole list; the ... button browses for a folder. The list persists across sessions.
Dist/Azim type
The approximation used by the Line length… and Azimuth… measure tools (right-click a line):
| Type | Engine | Notes |
|---|---|---|
Ellipsoidal | GMT.invgeod (Karney geodesic on WGS84) | exact ellipsoidal distance/azimuth |
Spherical | GMT.invgeod on a sphere (+proj=longlat +ellps=sphere) | great-circle |
Flat Earth | GMT.mapproject -jf | ignores meridian convergence (fast, least accurate at high latitude) |
Dir selects forward (default) or backward azimuths.
Measure units
Unit the Line length… tool reports in: meters, kilometers, nautical miles, or miles. Cartesian (non-geographic) objects are always reported in data units regardless of this setting.
Polygon area uses GMT.geodesicarea for Ellipsoidal and GMT.gmtspatial -Q otherwise (e.g. a spherical geographic area), reported in km² (+ m²).
Coastlines color
Line colour for the Geography menu's coastlines / political boundaries / rivers overlays. Limited to Black or White — any other colour is set per-object through Line Properties.
Default line color / thickness
Colour and width given to new lines and polygons drawn with the toolbar tools.
- Default line color — the leading entry, Orange, is the program's original line colour and the default, so the familiar look is preserved. The rest are the basic named colours; anything else is set per-line via Line Properties.
- Default line thickness —
1–4 pt. A point maps to1.25screen pixels, so2 pt(the default) is the historical2.5 pxwidth.