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Please see https://github.com/lutraconsulting/serval/blob/master/Serval/docs/user_manual.md

Serval wiki

Serval is a QGIS plugin for manipulating raster cell values.

Warning: Any changes are immediately written to disk. Make a copy of your precious raster.

How to use

1. Select a raster in the layers panel.
2. Pick the plugin maptool (if Serval dock widget is not visible, turn it on in View > Toolbars)
3. Choose the plugin mode:

• probing,
• drawing,
• erasing (applying a NoData value)

Probing mode

When a raster cell is clicked bands values are shown in spin box(es). Change them and hit Enter. Done.

Drawing mode

Set bands values in spin boxes and click raster cells that should get the values. For 3 bands rasters, a color can be chosen from native QGIS color picker.

Erasing mode

This tool applies a NoData value to raster cells. Plugin tries to read the source NoData and then user defined additional NoData value (see raster properties dialog 'Transparency'). One of these values must be defined for erasing.

Projections

Serval can work with the OTF reprojections. Nevertheless, it is advised that the raster and project CRS are the same for performance reasons.

NoData values

The plugin tries to get NoData value defined for the first band. If NoData is not defined, user can either:

• set a new NoData value to the raster source
• define user additional NoData value in raster properties dialog.

Undo/Redo

There is a history of changes for each raster layer. Un/Redoing is always done for active layer.

Known issues

When upgrading, QGIS needs to be restarted.

License

Serval is a free/libre software and is licensed under the GNU General Public License.