Re: [Geotools-devel] Proposed Oracle Georaster Mosaic Module

[Andrea A. <and...@ge...>]

On Wed, Feb 2, 2011 at 5:33 PM,  <chr...@nv...> wrote:
> ??? I do not understand at all.
> Within the new extended border, I need the pixels from the neighbor tiles.
>
> Normally, if I have a big image,
> I create the pyramids and finally create the tiles for all levels.
>
> If I create the the tiles first and the pyramids for each tile individually,
> it is possible that the tiles are different.

That may be a bug in the tile creation process?

If the tile creation itself is using bilinear/bicubic interpolation
the proper way to
do compute a tile at level N is not to take just 4 tiles at level N - 1, but
also all the neighbouring tiles in order to include the necessary border
for the interpolation to work, crop so that only the required extra border
is taken into account, rescale with interpolation, crop again to remove the
eventual extra pixels that get in the result as an effect of having considered
the extra border.
If a tile happens to sit at the overall mosaic limits add a copy border extender
to care for that case.

The javax.media.jai.Interpolation class do provide information about how big
the border should be in each direction (see the get*Padding methods)

Cheers
Andrea


-- 
Ing. Andrea Aime
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