---
name: "r.shaded.relief"
section: "1grass"
platform: "linux"
package: "grass-doc"
version: "6.4.4-1"
release: "Debian 8 (Jessie)"
platforms: ["linux"]
url: "https://new.carta.tech/r.shaded.relief"
---

# r.shaded.relief(1grass)

Creates shaded relief map from an elevation map (DEM).

## NAME

**r.shaded.relief**  - Creates shaded relief map from an elevation map (DEM).

## KEYWORDS

raster, elevation

## SYNOPSIS

**r.shaded.relief**\
 **r.shaded.relief help**\
 **r.shaded.relief map**=*string*  \[**shadedmap**=*string*\]   \[**altitude**=*float*\]   \[**azimuth**=*float*\]   \[**zmult**=*float*\]   \[**scale**=*float*\]   \[**units**=*string*\]   \[--**overwrite**\]  \[--**verbose**\]  \[--**quiet**\]

### Flags:

- **--overwrite**

  Allow output files to overwrite existing files

- **--verbose**

  Verbose module output

- **--quiet**

  Quiet module output

### Parameters:

- **map**=*string*

  Input elevation map

- **shadedmap**=*string*

  Output shaded relief map name

- **altitude**=*float*

  Altitude of the sun in degrees above the horizon\
   Options: *0-90*\
   Default: *30*

- **azimuth**=*float*

  Azimuth of the sun in degrees to the east of north\
   Options: *0-360*\
   Default: *270*

- **zmult**=*float*

  Factor for exaggerating relief\
   Default: *1*

- **scale**=*float*

  Scale factor for converting horizontal units to elevation units\
   Default: *1*

- **units**=*string*

  Set scaling factor (applies to lat./long. locations only, none: scale=1)\
   Options: *none,meters,feet*\
   Default: *none*

## DESCRIPTION

*r.shaded.relief* creates a raster shaded relief map based on current resolution settings and on sun altitude, azimuth, and z-exaggeration values entered by the user. If no output shademap name is given, the new shaded relief map is named *.shade*. The map is assigned a grey-scale color table.

The parameters controlling the shading are:

- **1**

  A raster map layer to provide elevation values for the shaded  relief map.  Typically, this would be a map layer of elevation;  however, any raster map layer can be named.

- **2**

  The **altitude** of the sun in degrees above the horizon (a value between 0 and 90 degrees).

- **3**

  The **azimuth** of the sun in degrees to the east of north (a value between 0 and 360 degrees; clockwise from north).

- **4**

  The scaling parameter, which compensates for a different  horizontal **scale** than vertical scale. If **scale** is a  number, then the ewres and nsres are multiplied by that scale to  calculate the shading. (Default=1.0 for equivalent horizontal and  vertical scales.)

- **5**

  For the special case when a latitude-longitude projection is used with an elevation map measured in meters (e.g., SRTM, ETOPO2 etc.) or feet, the  **units** can be set to automatically set the horizontal scale to the the number of  meters (scale=111120) or feet (scale=370400) in a degree of latitude. The script scales latitude and longitude equally, so it's only approximately right, but for shading  it is close enough. It makes the difference between a usable and unusable shade. The **units** parameter overrides the **scale** parameter.

- **6**

  The **zmult** exaggeration factor that changes the apparent relief for the shaded relief map.  This can be any positive (or negative) floating point value. (Default=1.0)

Specifically, *r.shaded.relief* executes a *r.mapcalc* statement. Refer to the manual entry for *r.mapcalc* for an explanation of the filtering syntax shown in the above expression. See, for example, the section on "The Neighborhood Modifier".

*r.shaded.relief* assigns a grey-scale color table to the new  shaded relief map.

## NOTES

To visually improve the result of shade maps from low resolution elevation models, use *r.resamp.interp* with bilinear or bicubic method to resample the DEM at higher resolution. *r.shaded.relief* is then run on the resampled DEM.

## EXAMPLES

In this example, the aspect map in the North Carolina sample dataset location is used to hillshade the elevation map:\
 `g.region rast=elevation -p`\
 `r.shaded.relief map=elevation shadedmap=elevation.shaded`\

In Latitude-Longitude locations (or other non-metric locations), the *scale* factor has to be used:\
 `# Latitude-Longitude example`\
 `r.shaded.relief map=srtm shadedmap=srtm.shaded scale=111120`\

## SEE ALSO

"*r.mapcalc: An Algebra for GIS and Image Processing*", by Michael Shapiro and Jim Westervelt, U.S. Army Construction Engineering Research Laboratory (March/1991) (PDF).

*d.his,* *g.region,* *r.blend,* *r.colors,* *r.mapcalc,* *r.resamp.interp*

## AUTHOR

Jim Westervelt, U.S. Army Construction Engineering  Research Laboratory

*Last changed: $Date: 2014-05-10 23:07:57 +0200 (Sat, 10 May 2014) $*

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