How to rasterize a river vector file and merge it to another raster layer?

Question

I got a river vector file.
I want to rasterize it so that the river is 2 pixels wide.
How do I achieve that in QGIS 3.2.3?

When I try to use vector to raster, I get this and no file is created:

Algorithm 'Rasterize (vector to raster)' starting…
Input parameters:
{ 'BURN' : 0, 'DATA_TYPE' : 5, 'EXTENT' : '413885.10813709395,678750.4296324956,6754403.012272906,6909638.055526119 [EPSG:32635]', 'FIELD' : None, 'HEIGHT' : 0, 'INIT' : 0, 'INPUT' : 'C:\Users\vvaris\Desktop\Uoma\Uoma10.shp', 'INVERT' : False, 'NODATA' : 0, 'OPTIONS' : '', 'OUTPUT' : 'C:/Users/vvaris/Desktop/asd.tif', 'UNITS' : 0, 'WIDTH' : 0 }

GDAL command:

gdal_rasterize -l Uoma10 -burn 0.0 -ts 0.0 0.0 -a_nodata 0.0 -te 413885.10813709395 6754403.012272906 678750.4296324956 6909638.055526119 -ot Float32 -of GTiff C:UsersvvarisDesktopUomaUoma10.shp C:/Users/vvaris/Desktop/asd.tif

GDAL command output:

ERROR 1: Wrong value for -outsize parameter.

Usage:

gdal_rasterize [-b band]* [-i] [-at]

{[-burn value]* | [-a attribute_name] | [-3d]} [-add]

[-l layername]* [-where expression] [-sql select_statement]

[-dialect dialect] [-of format] [-a_srs srs_def]

[-co "NAME=VALUE"]* [-a_nodata value] [-init value]*

[-te xmin ymin xmax ymax] [-tr xres yres] [-tap] [-ts width height]

[-ot {Byte/Int16/UInt16/UInt32/Int32/Float32/Float64/

CInt16/CInt32/CFloat32/CFloat64}] [-q]

<src_datasource> <dst_filename>

Execution completed in 0.13 seconds

Results:

{'OUTPUT': <QgsProcessingOutputLayerDefinition {'sink':C:/Users/vvaris/Desktop/asd.tif, 'createOptions': {'fileEncoding': 'System'}}>}

Loading resulting layers
Algorithm 'Rasterize (vector to raster)' finished

qgis

radouxju · Answer

If your vector is a line, you cannot ask for a width of 2 pixels. I suggest you to make a buffer around the line to give it the necessary width, then only rasterize your output. Don't forget to specify the output raster resolution (e.g. -tr 10 10 for 10 m pixel) and don't use the -ts option.
note that converting to float is probably not necessary, but you don't mention the type of values in the field used for the conversion.

Roberto Zeeland · Answer

You need to know the width of the river. 
Once you know that, just use Convert vector to raster and select a cell size half the width of the river.

How to rasterize a river vector file and merge it to another raster layer?

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