[gdal-dev] Tiled GeoTiff that reduce the amount of reads in XYZ maps

[Guy Doulberg]

it is 1/3 because the original was not compressed,

anyhow I am still getting too many requests when fetching a tile, maybe my
read code is not doing what I think it is doing



On Sun, Jun 17, 2018 at 4:51 PM, Guy Doulberg <guyd at satellogic.com> wrote:

> Thanks Even
>
> I tried both ways and in both I am still getting a lot of requests, I am
> exepcting only few, one for the headers and one for the tile:
>
>
> The resolution I used is driven from https://wiki.openstreetmap.
> org/wiki/Zoom_levels
>
> and the bounds I calculated using mercantile
>
> so an example of what I ran is:
>
> gdal_translate source.tif target.tif -co TILED=YES -co
> COPY_SRC_OVERVIEWS=YES -co COMPRESS=LZW -tr 0.596 0.596   -projwin
> 675091.8338146766 4706074.957461731 684875.7734351791 4696291.017841227
>
> One more thing, the raster I got is 1/3 of the size of the original raster
>
> On Sun, Jun 17, 2018 at 12:00 PM, Even Rouault <even.rouault at spatialys.com
> > wrote:
>
>> On dimanche 17 juin 2018 10:19:34 CEST Guy Doulberg wrote:
>> > Hi all,
>> >
>> > I am trying to use cloud optimized geotiff(cog) to reduce the block
>> fetched
>> > when accessing a raster.
>> >
>> > The use case I am trying to build, is a TileServer that serves tile in
>> > openlayer map.
>> > The rasters are to be stored on a remote location, in my case azure blob
>> > storage.
>> >
>> > We were able to do that, and you can see the code here:
>> > https://github.com/satellogic/telluric/blob/master/telluric/
>> > georaster.py#L1497
>> >
>> > The problem is, when running in verbose mode I can see that there are
>> many
>> > requests to the blob storage,
>> >
>> > I am responsible of creating the raster, is there a way in your opinion
>> I
>> > can create the raster aligned to the XYZ tiling system so when I try to
>> > fetch a tile from the raster I will be able to do that with a single or
>> > close to that call?
>>
>> If your raster source is not already in WebMercator projection, you could
>> use
>> gdalwarp with the appropriate -te and -tr to align on the boundaries of
>> XYZ
>> tiling scheme at a given zoom level.
>>
>> If your raster is already in WebMercator, gdal_translate -projwin -tr
>> would do
>>
>> If you don't want to compute the bounds, you could use gdal_translate to
>> MBTiles that will use gdalwarp internally to reproject and align on XYZ
>> tiling
>> scheme automatically, followed by gdal_translate to TIFF with -oo
>> USE_BOUNDS=NO so that the extent used aligns on tile boundaries.
>>
>> Even
>>
>> --
>> Spatialys - Geospatial professional services
>> http://www.spatialys.com
>>
>
>
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