d.geodesic(1)

💫 d.geodesic(1) — GRASS GIS User's Manual 💫

okay bestie, welcome to d.geodesic, a lil display module from the GRASS GIS fam that draws the actual shortest path between two points on a globe. like, the real shortest path, along a great circle. it's giving geography nerd main character energy and we're obsessed 💖

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✨ NAME ✨

d.geodesic — draws a geodesic line, tracing the shortest distance between two geographic points along a great circle, inside a longitude/latitude data set. periodt, that's the whole job 🎀

🔑 KEYWORDS 🔑

display, distance, great circle, shortest path

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🦋 SYNOPSIS 🦋

d.geodesic
d.geodesic --help
d.geodesic coordinates=lon1,lat1,lon2,lat2  [line_color=name]
[text_color=name]   [units=string]   [--help]  [--verbose]  [--quiet]
[--ui]

🚩 Flags 🚩

• --help — prints the usage summary, so you get the whole vibe explained back at you
• --verbose — verbose module output, it will literally narrate everything
• --quiet — quiet module output, no yapping allowed
• --ui — forces the GUI dialog to launch, for the girlies who like buttons

🎯 Parameters 🎯

• coordinates=lon1,lat1,lon2,lat2 — required, no skipping this one. the starting and ending coordinates, that's the whole point bestie
• line_color=name — the line color. either a standard color name or an R:G:B triplet. default: black
• text_color=name — the text color. either a standard color name or an R:G:B triplet (yes it's a whole vibe, no default listed here 💅)
• units=string — Units. (yes, the original says "Units" twice, iconic.) Options: meters, kilometers, feet, miles. Default: meters

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🌸 DESCRIPTION 🌸

d.geodesic displays a geodesic line in the active frame on the user's graphics monitor. that's also known as the great circle line, and it traces the shortest distance between two user-specified points on the curved surface of a longitude/latitude data set. so like, not a straight line on a flat map — a real curve on a real sphere, slay 🌈

the two coordinate locations you name must fall within the boundaries of your current geographic region. if they don't, that's a you problem, bestie 🫶

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💅 OPTIONS 💅

by default, black line color and red text color will be used. cute, classic, no notes ✨

by indicating the starting and ending coordinates of the geodesic, the line and its length (by default in meters) are displayed to the graphical output. so you get the pretty line and the receipts 🔥

if the text color is set to none, the great circle distance is not displayed. so like, if you want the line but not the number, that's your move. no cap.

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⭐ EXAMPLE ⭐

a geodesic line is shown over the political map of the world (demolocation dataset):

g.region vector=country_boundaries -p
d.mon wx0
d.vect country_boundaries type=area
# show additionally a 20 degree grid
d.grid 20
d.geodesic coordinates=55:58W,33:18S,26:43E,60:37N \
  line_color=yellow text_color=red units=kilometers

Geodesic line (great circle line)

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🧚 NOTES 🧚

this program works only with longitude/latitude coordinate system. like, only. don't try it elsewhere, it's not built different 🙈

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👑 SEE ALSO 👑

d.rhumbline, d.grid, m.measure

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💜 AUTHOR 💜

Michael Shapiro, U.S. Army Construction Engineering Research Laboratory

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💖 SOURCE CODE 💖

Available at: d.geodesic source code (history)

Accessed: Saturday Jan 17 05:40:34 2026

Main index | Display index | Topics index | Keywords index | Graphical index | Full index

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and that's the whole page, bestie!! 🎀 this was GRASS GIS 8.4.2, page d.geodesic(1), accessed on that Saturday Jan 17 05:40:34 2026 moment, © 2003-2025 GRASS Development Team, straight out of the GRASS GIS 8.4.2 Reference Manual. go draw some great circles, you ate 💅✨🦋