overview.py

# SPDX-License-Identifier: MIT
# Copyright 2020 Even Rouault

import time

from osgeo import gdal


def doit(compress, threads):

    gdal.SetConfigOption("GDAL_NUM_THREADS", str(threads))

    filename = "/vsimem/test.tif"
    ds = gdal.GetDriverByName("GTiff").Create(
        filename, 20000, 20000, 3, options=["COMPRESS=" + compress, "TILED=YES"]
    )
    ds.GetRasterBand(1).Fill(50)
    ds.GetRasterBand(3).Fill(100)
    ds.GetRasterBand(3).Fill(200)
    ds = None

    ds = gdal.Open(filename, gdal.GA_Update)
    start = time.time()
    ds.BuildOverviews("CUBIC", [2, 4, 8])
    end = time.time()
    print("COMPRESS=%s, NUM_THREADS=%d: %.2f" % (compress, threads, end - start))

    gdal.SetConfigOption("GDAL_NUM_THREADS", None)


doit("NONE", 0)
doit("NONE", 2)
doit("NONE", 4)
doit("NONE", 8)

doit("ZSTD", 0)
doit("ZSTD", 2)
doit("ZSTD", 4)
doit("ZSTD", 8)