Compressing raster using PyQGIS?

Question

I have the following code which batch saves rasters in qgis using the python terminal:

myDir = 'd:/output/'
layers = iface.legendInterface().layers()
pipe = QgsRasterPipe()
for layer in layers:
    extent = layer.extent()
    width, height = layer.width(), layer.height()
    renderer = layer.renderer()
    provider=layer.dataProvider()
    crs = layer.crs().toWkt() 
    pipe.set(provider.clone())
    pipe.set(renderer.clone())
    file_writer = QgsRasterFileWriter(myDir + layer.name() + ".tif")
    file_writer.writeRaster(pipe,
                            width,
                            height,
                            extent,
                            layer.crs())

The tifs that are saved are uncompressed, does anyone know how to turn on compression like LZW?

Answer 1

You could try adding the following two lines:

opts = ["COMPRESS=LZW"]     # <== ADD THIS ONE (1)
...
file_writer = QgsRasterFileWriter(myDir + layer.name() + ".tif")
...
file_writer.setCreateOptions(opts)           # <== ADD THIS ONE (2)
...
file_writer.writeRaster(pipe,
                        width,
                        height,
                        extent,
                        layer.crs())

Review of the qgsrasterfilewriter code shows we can pass any of the GDAL raster file creation/manipulation options to the QgsRasterDataProvider class via the setCreateOptions function which accepts a string list (QStringList) of options.