r.circle(1)

✨ r.circle ✨

okay bestie, this is straight outta the GRASS GIS User's Manual — page r.circle(1) — and it's genuinely so fun, let's go 💖

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🎯 NAME 🎯

• r.circle — creates a raster map containing concentric rings around a given point. like, ripples in a pond but make it spatial data 🫶

KEYWORDS 🏷️

raster, buffer, geometry, circle

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🌸 SYNOPSIS 🌸

r.circle
r.circle --help
r.circle [-b] output=name coordinates=east,north  [min=float]
[max=float]   [multiplier=float]   [--overwrite]  [--help]  [--verbose]
[--quiet]  [--ui]

🚩 Flags

• -b — generate a binary raster map (solid one-value vibes only, no gradient 💅)
• --overwrite — allow output files to overwrite existing files (yes, it will eat your old file, consent granted)
• --help — print usage summary
• --verbose — verbose module output
• --quiet — quiet module output (shhh 🤫)
• --ui — force launching GUI dialog

🎀 Parameters

• output=name [required] — name for the output raster map, name it something cute
• coordinates=east,north [required] — the coordinate of the center (east,north), i.e. where the main character point lives 👑
• min=float — minimum radius for the ring/circle map (in meters)
• max=float — maximum radius for the ring/circle map (in meters)
• multiplier=float — data value multiplier

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💜 DESCRIPTION 💜

So r.circle creates an output raster map centered on the x,y values you specify with the coordinate parameter, and it goes all the way out to the edge of the current region. The output cell values increase linearly from the specified center — like a little glow-up the further you get from the middle ✨

The min and max parameters control the inner and outer output raster map radii, respectively. inner circle and outer circle, bestie, two rings of the same slay 🌈

The mult parameter can be used to multiply the output raster cells by a common factor. Note that this parameter does not affect the output raster position or size — only the z-values are changed with this parameter. so it's purely a values thing, not a geometry thing, no cap.

Binary-output raster maps (solid circles of one value, iconic) can be created with the -b flag. Raster maps so created can be used to create binary filters for use in i.ifft (inverse Fourier transformations; apply filter with r.mask). 🦋

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🌟 EXAMPLES 🌟

example one — gradient circle, current map center, radius 300m 🌸

Generate a raster circle at current map center with a radius of 300m and outwardly increasing raster values:

EASTCENTER=`g.region -c |  awk ’ /center easting:/ { print $3 }’`
NORTHCENTER=`g.region -c | awk ’ /center northing:/ { print $3 }’`
r.circle output=circle coordinate=${EASTCENTER},${NORTHCENTER} max=300

example two — binary ring, inner 500m, outer 1000m 💅

Generate a binary raster ring around current map center with an inner radius of 500m and an outer radius of 1000m:

EASTCENTER=`g.region -c |  awk ’ /center easting:/ { print $3 }’`
NORTHCENTER=`g.region -c | awk ’ /center northing:/ { print $3 }’`
r.circle -b output=circle coordinate=${EASTCENTER},${NORTHCENTER} min=500 max=1000

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👀 SEE ALSO 👀

g.region, g.remove, g.rename, i.fft, i.ifft, r.mask

go read those next, iykyk 🧚

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🫶 AUTHORS 🫶

• Bill Brown, U.S. Army Construction Engineering Research Laboratory
• Additional flag/min/max parameter by Markus Neteler, University of Hannover

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💻 SOURCE CODE 💻

Available at: r.circle source code (history)

Accessed: Saturday Jan 17 05:40:43 2026

Main index | Raster index | Topics index | Keywords index | Graphical index | Full index

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okay that's the whole page, you ate that. go make some circles. periodt. 💖✨

and a lil sign-off bestie — this whole thing is © 2003-2025 GRASS Development Team, from the GRASS GIS 8.4.2 Reference Manual, and you were reading r.circle(1) with me, GRASS 8.4.2 edition, accessed Saturday Jan 17 05:40:43 2026. mwah 🎀🦋💜