r.spreadpath(1grass)

💖 r.spreadpath — the manual page, but make it bestie ✨

okay so welcome to r.spreadpath(1grass), the GRASS User's Manual page that literally walks your fire backwards to where it came from. she's giving detective energy. 🔥

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🌈 NAME 🌈

r.spreadpath — recursively traces the least cost path backwards to cells from which the cumulative cost was determined.

🎀 KEYWORDS 🎀

raster, fire, cumulative costs

✨ SYNOPSIS ✨

r.spreadpath
r.spreadpath --help
r.spreadpath x_input=name y_input=name
[coordinates=east,north[,east,north,...]]  output=name  [--overwrite]
[--help]  [--verbose]  [--quiet]  [--ui]

🫶 Flags

• --overwrite — allow output files to overwrite existing files. yes queen, she will absolutely replace what's there, so be aware 💅
• --help — print usage summary
• --verbose — verbose module output. all the tea ☕
• --quiet — quiet module output. no yapping 🤫
• --ui — force launching GUI dialog

🌸 Parameters

• x_input=name [required] — Name of raster map containing back-path easting information
• y_input=name [required] — Name of raster map containing back-path northing information
• coordinates=east,north[,east,north,...] — The map E and N grid coordinates of starting points
• output=name [required] — Name for output raster map

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💜 DESCRIPTION 💜

r.spreadpath is part of the wildfire simulation toolset. The preparational steps for the fire simulation are, in order, the calculation of the rate of spread (ROS) with r.ros, and the creating of a spread map with r.spread. And eventually, the fire path(s) based on starting point(s) get calculated with r.spreadpath. the whole pipeline is iconic honestly 🔥

r.spreadpath recursively traces the least cost path backwards to the origin, given backlink information input map layers and target locations from where paths are to be traced. The backlink information map layers record each cell's backlink UTM northing (the y_input) and easting (the x_input) coordinates from which the cell's cumulative cost was determined. so basically every cell remembers where it came from, and this module reads the receipts. 👑

The backlink inputs can be generated from another GRASS raster program, r.spread. One of the major applications of r.spreadpath along with r.spread is to accurately find the least cost corridors and/or paths on a raster setting. More information on r.spread and r.spreadpath can be found in Xu (1994).

🌟 Parameters

• x_input=name — Name of input raster map layer containing backlink UTM easting coordinates.
• y_input=name — Name of input raster map layer containing backlink UTM northing coordinates.
• coordinates =x,y[,x,y,x,y, ...] — Each x,y coordinate pair gives the easting and northing (respectively) geographic coordinates of a target point from which to backwards trace the least cost path. As many points as desired can be entered by the user. go off, enter a hundred of them, she can handle it 💅
• output=name — Name of raster map layer to contain output. Also can be used as the map layer of the input target points. If so used, the input target point map will be overwritten by the output. 🙈

bestie, that last one is a real warning, not a vibe. if you point output at the same map you're using as your input target points, that input map gets overwritten. no take-backs.

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📚 REFERENCES 📚

• Xu, Jianping, 1994, Simulating the spread of wildfires using a geographic information system and remote sensing, Ph. D. Dissertation, Rutgers University, New Brunswick, New Jersey (ref).

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👀 SEE ALSO 👀

r.spread, r.ros

Sample data download: firedemo.sh (run this script within the "Fire simulation data set" project).

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👑 AUTHORS 👑

Jianping Xu and Richard G. Lathrop, Jr., Center for Remote Sensing and Spatial Analysis, Rutgers University.

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💻 SOURCE CODE 💻

Available at: r.spreadpath source code (history)

Latest change: Monday Feb 24 16:07:55 2025 in commit: 4ab71fd34113b347c3c86c736cd82ca0f6be1d4b

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

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okay that's the whole page, no notes, literally every flag accounted for. mwah. 💅✨

and a lil sign-off for the record: this is the © 2003-2026 GRASS Development Team, GRASS 8.5.0 Reference Manual, footer stamped GRASS 8.5.0 and r.spreadpath(1grass) — latest change Monday Feb 24 16:07:55 2025 in commit 4ab71fd34113b347c3c86c736cd82ca0f6be1d4b. slay, go trace some paths 🦋🌸