[gdal-dev] Fwd: GeoPKG Zoom Level Calculation

[Roarke Gaskill]

Very cool, thank you for the explanation and the doc update.



On Thu, Sep 14, 2017 at 6:42 AM, Even Rouault <even.rouault at spatialys.com>
wrote:

> On jeudi 14 septembre 2017 06:26:40 CEST Roarke Gaskill wrote:
>
> > Even,
>
> >
>
> > Thanks for your reply. I get it now. :)
>
> >
>
> > I am new to gdal in general. For context, why does CreateCopy() choose
> the
>
> > nearest zoom level and not SetGeoTransform()?
>
>
>
> Most drivers don't handle directly this concept of predefined tiling
> schemes, and if you want to apply one, you need to use gdalwarp and setting
> correctly the extent, resolution, etc... The CreateCopy() implementation in
> the GPKG driver, when tiling scheme is specified, does that automatically
> for you.
>
>
>
> But if you do SetGeoTransform() manually and then use the RasterIO() API,
> no resampling can occur at that level of the driver (like any other
> drivers), so you have to specify a resolution that respect the constraints
> of the tiling scheme.
>
>
>
> > As a new user, it seems to
>
> > me the ZOOM_LEVEL_STRATEGY should apply to both the SetGeoTransform() and
>
> > CreateCopy().
>
>
>
> I've just added a precision in the doc to mention that ZOOM_LEVEL_STRATEGY
> only applies to CreateCopy()
>
>
>
> Even
>
>
>
> --
>
> Spatialys - Geospatial professional services
>
> http://www.spatialys.com
>



-- 
*Roarke **Gaskill  *|Senior Software Engineer
*e:* roarke.gaskill at weather.com
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