View source for QGIS Export Raster to asc

=Introduction=
A large number of different file formats are used for storing raster or DEM data.  In this page we will use QGIS to convert a format not recognised by TUFLOW into a format used by TUFLOW.  In this example a .dem file format is used. However, a large number of formats are supported in the GDAL raster formats, a list is provided here: [http://www.gdal.org/formats_list.html GDAL Raster Formats].
=Method=
<ol>
<li>Open the file you wish to convert by selecting '''Layer >> Add Raster Layer'''</li>
[[File:Qgis convert raster01.jpg]]
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<li>Open the raster translator by selecting '''Raster >> Conversions >>Translate'''</li>
[[File:Qgis convert raster02.jpg]]
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<li>Set the input layer and in the '''Output file''' press the '''Select Button'''</li>
<li>In the save dialogue, drop the file type down and select Arc/Info ASCII Grid (*.asc *.ASC).  Set a filename and path including the .asc extension. Press '''Save''' to close the dialogue.</li>
[[File:Qgis convert raster03.jpg]]
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<li>Press ok to perform the translation.</li>
[[File:Qgis convert raster04.jpg]]
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<li>The file is now ready for input in TUFLOW, the .tgc command is Read GRID Zpts == <dem.asc></li>


'''NOTE''', QGIS can default to the Golden Surfer type of ascii grid. This grid format does not have square cell sizes and is not currently supported by TUFLOW.
<br>There is more information on this issue in [http://gis.stackexchange.com/questions/118325/qgis-ascii-grid-output-problem| this stack exchange post.]
To correct this issue, add '-co force_cellsize=true' to the text box underneath the 'load into canvas when finished' button. Add the text after the word 'gdal_translate'
Caution, check your results as this may distort your grid