Using gdal in python to produce tiff files from csv files

Question

I have many csv files with this format:

Latitude,Longitude,Concentration
53.833399,-122.825257,0.021957
53.837893,-122.825238,0.022642
....

My goal is to produce GeoTiff files based on the information within these files (one tiff file per csv file), preferably using python. This was done several years ago on the project I am working on, however how they did it before has been lost. All I know is that they most likely used GDAL.

I have attempted to do this by researching how to use GDAL, but this has not got me anywhere, as there are limited resources and I have no knowledge of how to use this.

Can someone help me with this?

Answer 1

Here is a little code I adapted for your case. You need to have the GDAL directory with all the *.exe in added to your path for it to work (in most cases it's C:\Program Files (x86)\GDAL).

It uses the gdal_grid.exe util (see doc here: http://www.gdal.org/gdal_grid.html)

You can modify as you wish the gdal_cmd variable to suits your needs.

import subprocess
import os

# your directory with all your csv files in it
dir_with_csvs = r"C:\my_csv_files"

# make it the active directory
os.chdir(dir_with_csvs)

# function to get the csv filenames in the directory
def find_csv_filenames(path_to_dir, suffix=".csv"):
    filenames = os.listdir(path_to_dir)
    return [ filename for filename in filenames if filename.endswith(suffix) ]

# get the filenames
csvfiles = find_csv_filenames(dir_with_csvs)

# loop through each CSV file
# for each CSV file, make an associated VRT file to be used with gdal_grid command
# and then run the gdal_grid util in a subprocess instance
for fn in csvfiles:
    vrt_fn = fn.replace(".csv", ".vrt")
    lyr_name = fn.replace('.csv', '')
    out_tif = fn.replace('.csv', '.tiff')
    with open(vrt_fn, 'w') as fn_vrt:
        fn_vrt.write('<OGRVRTDataSource>\n')
        fn_vrt.write('\t<OGRVRTLayer name="%s">\n' % lyr_name)
        fn_vrt.write('\t\t<SrcDataSource>%s</SrcDataSource>\n' % fn)
        fn_vrt.write('\t\t<GeometryType>wkbPoint</GeometryType>\n')
        fn_vrt.write('\t\t<GeometryField encoding="PointFromColumns" x="Longitude" y="Latitude" z="Concentration"/>\n')
        fn_vrt.write('\t</OGRVRTLayer>\n')
        fn_vrt.write('</OGRVRTDataSource>\n')

    gdal_cmd = 'gdal_grid -a invdist:power=2.0:smoothing=1.0 -zfield "Concentration" -of GTiff -ot Float64 -l %s %s %s' % (lyr_name, vrt_fn, out_tif)

    subprocess.call(gdal_cmd, shell=True)