r.transect(1)

💖 r.transect(1) — GRASS GIS User's Manual 💖

okay bestie, welcome to the GRASS GIS manual page for r.transect(1), and lemme tell you, this one is so chill. 🦋

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✨ NAME ✨

r.transect — outputs raster map layer values lying along user defined transect line(s).

like. it literally just reads a raster along a line you drew in your head. iconic behavior. 👑

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🏷️ KEYWORDS 🏷️

raster, profile, transect

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🌸 SYNOPSIS 🌸

r.transect
r.transect --help
r.transect [-g] map=name
line=east,north,azimuth,distance[,east,north,azimuth,distance,...]
[null_value=string]   [--help]  [--verbose]  [--quiet]  [--ui]

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🎀 Flags:

• -g — outputs easting and northing in the first two columns of the four column output. so you get coordinates and values, four columns deep, periodt.
• --help — prints the usage summary. your emergency 411.
• --verbose — verbose module output. it will talk. a lot. main character energy.
• --quiet — quiet module output. it will not talk. shhh.
• --ui — force launching GUI dialog. for when you want the pretty buttons instead of the terminal grind.

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🧚 Parameters:

• map=name [required] — the raster map to be queried. you gotta tell it what to look at, no cap.
• line=east,north,azimuth,distance[,east,north,azimuth,distance,...] [required] — the transect definition. yes you can stack a bunch of them, separated by commas, and it will eat them all.
• null_value=string — string representing NULL value. Default: *

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💅 DESCRIPTION 💅

okay so r.transect outputs, in ASCII, the values in a raster map which lie along one or more user-defined transect lines. the transects are described by their starting coordinates, azimuth, and distance. that's it. that's the whole job. lowkey perfect.

the line parameter is a definition of (each) transect line, specified by the geographic coordinates of its starting point (easting, northing), the angle and direction of its travel (azimuth), and its distance. so like, point, angle, how far. a lil road trip through your raster. 🚗

the azimuth is an angle, in degrees, measured to the east of north. the distance is in map units (meters for a metered database, like UTM).

the null parameter can optionally be set to change the character string representing null values. so if * isn't your vibe, swap it out. 🙈

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📝 NOTES 📝

this program is a front-end to the r.profile program. it simply converts the azimuth and distance to an ending coordinate and then runs r.profile. so it's giving delegation, and honestly? respect. it knows its strengths.

🚨 lore drop: there once were width= and result=raw|median|average options which are not currently implemented. so don't come for them, they are ghosts. 💀

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👀 SEE ALSO 👀

• r.profile
• wxGUI profile tool

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👑 AUTHOR 👑

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

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🫶 SOURCE CODE 🫶

available at: r.transect source code (history)

accessed: Saturday Jan 17 05:41:03 2026

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© 2003-2025 GRASS Development Team, GRASS GIS 8.4.2 Reference Manual

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and that's the whole page bestie!! 💖✨🎀🦋🌸 this was GRASS 8.4.2, and the page was accessed on Saturday Jan 17 05:41:03 2026, straight out of the GRASS GIS 8.4.2 Reference Manual by the GRASS Development Team. slay, go profile something. 💅