Hi there,
I am running a Python script that goes through a relatively large number of
single band raster files (320) and aggregates it in a big-geotiff (around 7Gb)
and I am facing three basic problems *poor performance*,
*wrong results*" and *lost of metadata*.
I need that geotiff to be interleaved by pixel since the goal is to query for
historical values in a given location and return then in the best response time
possible.
So I am using this create options:
--
driver_tif = gdal.GetDriverByName("GTIFF")
output_dst = driver_tif.Create( output_tif, x_size, y_size, serie_count,
data_type,
[ 'TILED=NO', 'INTERLEAVE=PIXEL' ])
--
I also need to add custom metadata entries to the dataset and to the
individuals bands so that we know their data stamps.
That is how I loop to all the files and copy then to the output big-geotiff
file:
--
gdal.SetCacheMax(500)
count = 1
for i in list_tsf:
input_dst = gdal.Open( f )
input_band = input_dst.GetRasterBand( 1 )
output_band = output_dst.GetRasterBand( count )
output_band.WriteRaster( 0, 0, x_size, y_size, input_band.ReadRaster(
0, 0, x_size, y_size ) )
output_band.FlushCache()
count = count + 1
--
*Performance*: The process takes more than 6 hours.
(Wrong Results*: All the pixels are zero (0)
If I just change the script on 'INTERLEAVE=PIXEL' to 'INTERLEAVE=BAND' the
whole process takes around 30 minutes.
I can then use gdal_translate to convert from GTIFF to GTIFF with -co
'INTERLEAVE=PIXEL'. That takes another 30 minutes.
*Lost Metadata*: That looks like a solution except that I will then loose all
my custom metadata entries.
Does anybody have any idea to improve that process.
Thanks is advance,
Ivan
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