[gdal-dev] OpenJPEG

[Aaron Boxer]

Hi Jukka,


On Tue, Dec 22, 2015 at 4:34 AM, Jukka Rahkonen <
jukka.rahkonen at maanmittauslaitos.fi> wrote:

> Aaron Boxer <boxerab <at> gmail.com> writes:
>
>
> > This feature would be quite involved: one would have to gather all of the
> layers for
> >
> > all of the code blocks in all of the precincts overlapping that
> sub-tile,plus the immediately surrounding precincts, run the inverse
> entropy
> coder to get the wavelet coefficients, and then do an inverse wavelet
> transform,with this incomplete set of coefficients.
> >
>
> I do not claim that I understand GIS but I have a feeling that precincts
> are
> designed for a fast ROI access. From
> http://www2.engr.arizona.edu/~bilgin/publications/SPIE2004_2.pdf
>
> "A precinct is a collection of code-blocks representing some finite spatial
> extent at some resolution."
>

> Probably gathering the surrounding precincts is unnecessary. Author of
> Kakadu seems to dislike tiles and it is no wonder that with Kakadu
> precincts
> perform well even with archived documents
> http://www.digitizationguidelines.gov/still-image/documents/Martin.pdf.
>

Thanks. Yes, I think precincts are key. But, the way the wavelet transform
works,
there need to be a number of locations on the boundary of the precinct to
correctly
transform. I suppose bordering code blocks would be enough, the entire
precinct on
the border is not necessary.

Cheers,
Aaron
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