I have checked. Yes, in using S2 COG with images in tiff format gdal makes 5 requests for getting 100x100px images and speed significantly higher in comparison with jp2. Unfortunately the size of tiff-file in this case is twice higher than corresponding jp2.
On Mon, Nov 2, 2020 at 6:28 PM Patrick Young < patrick.mckendree.yo...@gmail.com> wrote: > You can check how a S2 COG compares at > > https://registry.opendata.aws/sentinel-2-l2a-cogs/ > > You should hopefully see a lot less network requests when accessing a sub > block directly. > > P > > > On Mon, Nov 2, 2020 at 7:58 AM Alexander Verbitsky <habibu...@gmail.com> > wrote: > >> Hi All, I am trying to implement remote reading small blocks of images, >> but find slow performance. >> >> For example i am trying to read 100x100 block from `sentinel-2` image, >> with using following code: >> >> filename = ( >> '/vsigs/gcp-public-data-sentinel-2/tiles/31/U/FS/' >> 'S2A_MSIL1C_20201024T104121_N0209_R008_T31UFS_20201024T125115.SAFE/' >> >> 'GRANULE/L1C_T31UFS_A027890_20201024T104121/IMG_DATA/T31UFS_20201024T104121_B08.jp2' >> ) >> ds = gdal.OpenEx(filename, gdal.OF_RASTER) >> band = ds.GetRasterBand(1) >> img = band.ReadAsArray(1000, 1000, 100, 100) >> >> In result I am getting more low performance in comparison if I just >> download the whole image in memory and then read the necessary block. AS I >> understand it happens due to a lot of small requests (is about 100) that >> are made during reading a small part of the image. Is it a fundamental >> feature of JP2OpenJPEG and this format not suitable for doing things like >> that? Should I take another format like GeoTiff and store my own data in >> it? Thank, for your reply. >> >> >> _______________________________________________ >> gdal-dev mailing list >> gdal-dev@lists.osgeo.org >> https://lists.osgeo.org/mailman/listinfo/gdal-dev > >
_______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/gdal-dev
