Thank you very much "Even Rouault" for making me understood. On Fri, Apr 3, 2015 at 8:13 PM, Even Rouault <[email protected]> wrote:
> Le vendredi 03 avril 2015 12:46:48, Yuta Sato a écrit : > > Dear Even Rouault: > > > > Thank you very much. > > What about setting these parameters "used with .ReadAsArray()", though I > > did not know their meanings? > > buf_xsize=None, buf_ysize=None, buf_obj=None > > (Please keep the list CC'ed) > > buf_xsize and buf_ysize are the equivalents of nBufXSize and nBufYSize in > GDALRasterBand::RasterIO() > http://gdal.org/classGDALRasterBand.html#a75d4af97b3436a4e79d9759eedf89af4 > i.e. to do downsampling or upsampling of original data. > > buf_obj can be used to "recycle" an existing numpy array of the appropriate > size instead of allocating a new one. > > > > > > > On Fri, Apr 3, 2015 at 7:43 PM, Even Rouault <[email protected] > > > > > > wrote: > > > Le vendredi 03 avril 2015 12:22:00, Yuta Sato a écrit : > > > > Dear Respected GDAL Developers and Users: > > > > > > > > What parameters should I set beforehand in order to accelerate the > > > > > > reading > > > > > > > of a GeoTiff file? > > > > > > > > I am using as follows: > > > > > > > > data = > src_dataset.GetRasterBand(1).ReadAsArray(xoff,yoff,xsize,ysize) > > > > > > > > Does setting the following parameters accelerate? > > > > > > > > GDAL_CACHEMAX, GDAL_SWATH_SIZE > > > > > > > > I'm using gdal python. > > > > > > Yuta, > > > > > > Increasing GDAL_CACHEMAX might accelerate in case of repeated reads on > > > windows > > > that are identical or overlapping already read windows. Or if the way > you > > > read > > > the raster doesn't follow its block shape : for example if the raster > is > > > organized by lines/strips and you read by square blocks, or the reverse > > > situation. > > > > > > GDAL_SWATH_SIZE is only used by CreateCopy(). > > > > > > Even > > > > > > -- > > > Spatialys - Geospatial professional services > > > http://www.spatialys.com > > -- > Spatialys - Geospatial professional services > http://www.spatialys.com >
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