---
name: "r.contour"
section: "1grass"
platform: "linux"
package: "grass-doc"
version: "8.4.1-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/r.contour"
---

# r.contour(1grass)

Produces a vector map of specified contours from a raster map.

## NAME

**r.contour**  - Produces a vector map of specified contours from a raster map.

## KEYWORDS

raster, surface, contours, vector

## SYNOPSIS

**r.contour**\
 **r.contour --help**\
 **r.contour** \[-**t**\] **input**=*name* **output**=*name*  \[**step**=*float*\]   \[**levels**=*float*\[,*float*,...\]\]   \[**minlevel**=*float*\]   \[**maxlevel**=*float*\]   \[**cut**=*integer*\]   \[--**overwrite**\]  \[--**help**\]  \[--**verbose**\]  \[--**quiet**\]  \[--**ui**\]

### Flags:

- **-t**

  Do not create attribute table

- **--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* **\[required\]**

  Name for output vector map

- **step**=*float*

  Increment between contour levels

- **levels**=*float\[,float*,...\]

  List of contour levels

- **minlevel**=*float*

  Minimum contour level

- **maxlevel**=*float*

  Maximum contour level

- **cut**=*integer*

  Minimum number of points for a contour line (0 -\> no limit)\
   Default: *2*

## DESCRIPTION

*r.contour* produces a vector map of specified contours from input raster map. Contours can be produced using a comma-separated list of values in **levels**, or at some regular increment using the **step** parameter, using **minlevel** and **maxlevel** as minimum and maximum contour values, respectively. If no **minlevel** or **maxlevel** is specified, the minimum and maximum cell values in the **input** raster map will be used.

## NOTES

*r.contour* will either step through incremental contours or produce contours from a list of levels, not both. If both a list of levels and a step are specified, the list will be produced and the step will be ignored.

Zero is treated as a valid data value by *r.contour*.

If a contour level exactly matches a category value in the raster map, the contour line may backtrack on itself, causing illegal arcs to be produced in the output vector map.

The optional **cut** parameter allows the user to specify a minimum number of raster cells eligilble to be included in a contour line written to the **output** vector map. It acts like a filter, omitting spurs, single points, etc., making the output more generalized.

## EXAMPLES

In the Spearfish dataset, produce a vector contour map from input raster *elevation.dem* with contour levels from 1000m to 2000m, 100m contour step, and a minimum of 200 input raster points contributing to the contour line:\

```
r.contour input=elevation.dem output=elevation_dem_contours \
          minlevel=1000 maxlevel=2000 step=100 cut=200
```

For an example of using levels with *r.contour* this example uses the elevation map from the North Carolina database:\

```
g.region raster=elevation
r.contour in=elevation out=contours levels=60,90,120,150 --o
d.mon wx0
d.rast elevation_shade
d.vect contours color=red
```

*Contour lines shown on shaded terrain map*

For an example of using steps with *r.contour* this example uses the LiDAR data derived elevation map from the North Carolina database:\

```
g.region raster=elev_lid792_1m -p
r.contour input=elev_lid792_1m output=elev_lid792_1m_contours \
          minlevel=100 maxlevel=150 step=10
```

## AUTHORS

Terry Baker, U.S. Army Construction Engineering Research Laboratory\
 3/2001: cut parameter and fixes by Andrea Aime (aaime@libero.it)

## SOURCE CODE

Available at: r.contour source code (history)

Accessed: Monday Feb 24 17:50:35 2025

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