Merging many rasters with Python script within QGIS using GDAL?

Question

I have many rasters that im trying to combine in order to produce contours. They are in the .bil format so I understand that i need to translate them using gdal first but none of my attempts have worked.

I have tried to used gdal_translate and gdal_merge with no success.

import os 
import sys
import gdal 
chdir C:\Users\jeswa\Desktop\GAL
SDKShell.bat
chdir C:\Users\jeswa\Desktop\TESTY
dir /s/b *.bil >listbil.txt
gdalbuildvrt -input_file_list listbil.txt testscript.vrt
#error does not like N34025raster but passes 44 and 45
gdal_translate -of GTiff C:\Users\jeswa\Desktop\TESTY\testscript.vrt C:/Users/jeswa/Desktop/TESTY/VIRTUALTIFF.tif
#no such thing as gdal_translate apparently

• Michael Stimson: What error messages are you getting? What is the value of your %PATH% after SDKShell? I use a very similar process to this and it works well; you could try CD c:\your\path\to\GDAL\bin so you can (hopefully) find translate.
• Jesse Warren: i’ve decided to skip the translate and produce contours from my vrt, is this acceptable?
• Michael Stimson: It should be but be aware that VRT is a slower raster format than a single image file, if you can translate to GeoTIFF with no compression your contours will run much faster.
• alphabetasoup: Why are you doing Python imports in your shell script? Is that some error of formatting in your question?
• Jesse Warren: i’m not really sure how to work through QGIS python, which is a requirement, and i only really have experience with arcpy

Answer 1

QGIS can read BIL files. And you can merge the individual files using Processing Algorithms via Python without using GDAL directly.

• Load individual files in QGIS (bulk drag/drop)
• Open Python Console
• Call the processing algorithm gdal:merge via processing.run()

A very similar example is at http://www.qgistutorials.com/en/docs/3/processing_algorithms_pyqgis.html