[gdal-dev] Do RasterIO of VRT format using arbitrary overviews of origin files

Previous Topic Next Topic
 
classic Classic list List threaded Threaded
2 messages Options
Reply | Threaded
Open this post in threaded view
|

[gdal-dev] Do RasterIO of VRT format using arbitrary overviews of origin files

Zi Chui
Hello,

I have some jpeg2000 files, and i know this format support arbitrary overviews,
GdalRasterBand::RasterIO will automatically use it in downsampling mode.

But i noticed that the vrt file generated by those jp2 files do not has arbitrary overviews (GdalRasterBand::HasArbitraryOverviews return FALSE). 

So here goes my question, dose GdalRasterBand::RasterIO of VRT format still using arbitrary overviews of origin files? 

It will be very helpful if anyone can answer my question.


_______________________________________________
gdal-dev mailing list
[hidden email]
https://lists.osgeo.org/mailman/listinfo/gdal-dev
Reply | Threaded
Open this post in threaded view
|

Re: Do RasterIO of VRT format using arbitrary overviews of origin files

Even Rouault-2

On vendredi 2 février 2018 11:28:08 CET Zi Chui wrote:

> Hello,

>

> I have some jpeg2000 files, and i know this format support arbitrary

> overviews,

> GdalRasterBand::RasterIO will automatically use it in downsampling mode.

>

> But i noticed that the vrt file generated by those jp2 files do not

> has arbitrary

> overviews (GdalRasterBand::HasArbitraryOverviews return FALSE).

>

> So here goes my question, dose GdalRasterBand::RasterIO of VRT format still

> using arbitrary overviews of origin files?

 

Yes, even if the VRT driver doesn't expose all capabilities of underlying sources, it is able to do efficient dowsampling if the sources support it.

 

Even

 

--

Spatialys - Geospatial professional services

http://www.spatialys.com


_______________________________________________
gdal-dev mailing list
[hidden email]
https://lists.osgeo.org/mailman/listinfo/gdal-dev