r.object.geometry - GRASS manual
Author: GRASS Development Team
Description: r.object.geometry: Calculates geometry parameters for raster objects.
Keywords: raster, statistics, reclass, clumps

## NAME

r.object.geometry - Calculates geometry parameters for raster objects.

## KEYWORDS

raster, statistics, reclass, clumps

## SYNOPSIS

r.object.geometry
r.object.geometry --help
r.object.geometry [-m] input=name [output=name] [separator=character] format=name [--overwrite] [--help] [--verbose] [--quiet] [--ui]

### Flags:

-m
  Use meters as units instead of cells
--overwrite
  Allow output files to overwrite existing files
--help
  Print usage summary
--verbose
  Verbose module output
--quiet
  Quiet module output
--ui
  Force launching GUI dialog

### Parameters:

input=name [required]
  Name of input raster map
output=name
  Name for output file
separator=character
  Field separator
  Special characters: pipe, comma, space, tab, newline
  Default: pipe
format=name [required]
  Output format
  Options: plain, json
  Default: plain
  plain: Plain text output
  json: JSON (JavaScript Object Notation)

## DESCRIPTION

r.object.geometry calculates form statistics of raster objects in the input map and writes it to the output text file (or standard output if no output filename or '-' is given), with fields separated by the chosen separator. Objects are defined as clumps of adjacent cells with the same category value (e.g. output of r.clump or i.segment).

By default, values are in pixels. If values in meters is desired, the user can set the -m flag. If the current working region is in lat-long or has non-square pixels, using meters is recommended.

Statistics currently calculated are exactly the same as in v.to.db (except for compact_square and mean coordinates):

- area
- perimeter
- compact_square (compactness compared to a square: `compact_square = 4 * sqrt(area) / perimeter`)
- compact_circle (compactness compared to a circle: `compact_circle = perimeter / ( 2 * sqrt(PI * area) )`)
- fractal dimension ( `fd = 2 * ( log(perimeter) / log(area + 0.001) )` )
- mean x coordinate of object (in map units)
- mean y coordinate of object (in map units)

## EXAMPLE

    g.region raster=soilsID
    r.object.geometry input=soilsID output=soils_geom.txt

The format=json option can be used to change the output format to JSON:

    r.object.geometry input=zipcodes format=json

    [
        {
            "category": 1,
            "area": 106,
            "perimeter": 62,
            "compact_circle": 1.6987670351864215,
            "compact_square": 0.66423420264432265,
            "fd": 1.7699924681225903,
            "mean_x": 631382.07547169807,
            "mean_y": 222764.15094339623
        },
        {
            "category": 2,
            "area": 57,
            "perimeter": 36,
            "compact_circle": 1.3451172460704992,
            "compact_square": 0.83887049280786108,
            "fd": 1.772672742164326,
            "mean_x": 643460.52631578944,
            "mean_y": 217232.45614035087
        },
        {
            "category": 3,
            "area": 10,
            "perimeter": 16,
            "compact_circle": 1.4272992929222168,
            "compact_square": 0.79056941504209488,
            "fd": 2.4081353865496951,
            "mean_x": 631300,
            "mean_y": 215450
        },
        {
            "category": 4,
            "area": 63,
            "perimeter": 60,
            "compact_circle": 2.1324361862292305,
            "compact_square": 0.52915026221291817,
            "fd": 1.9764401337147652,
            "mean_x": 642345.23809523811,
            "mean_y": 226599.20634920636
        },
        {
            "category": 5,
            "area": 491,
            "perimeter": 156,
            "compact_circle": 1.9859985189304281,
            "compact_square": 0.56816717451693177,
            "fd": 1.6299200778082998,
            "mean_x": 637912.93279022397,
            "mean_y": 220636.96537678209
        },
        {
            "category": 6,
            "area": 83,
            "perimeter": 60,
            "compact_circle": 1.8578355639603314,
            "compact_square": 0.60736223860961991,
            "fd": 1.8531256328449071,
            "mean_x": 635846.38554216863,
            "mean_y": 227219.8795180723
        }
    ]

## SEE ALSO

i.segment, r.clump, v.to.db

## AUTHORS

Moritz Lennert
Markus Metz (diagonal clump tracing)

## SOURCE CODE

Available at: r.object.geometry source code (history)

Latest change: Thursday Nov 06 22:27:54 2025 in commit: 298b38614712934179355ea767403d6bfea8f5f9

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