[GRASS-user] Viewing ecw files
rez at touchofmadness.com
Thu Feb 15 17:14:36 EST 2007
On Thu, 2007-02-15 at 20:55 +0100, Maciej Sieczka wrote:
> nicholas.g.lawrence at mainroads.qld.gov.au wrote:
> >> It would be really nice if GRASS had a wavelet based scheme for imagery,
> >> but that would require significant development and many of us don't have
> >> the spare time available. At the moment, Hamish's suggestion is about
> >> the best that can be done. GRASS cannot handle such large datasets with
> >> efficiency.
> >> ECW is a wonderful format. It is hard to beat the compression and speed
> >> of scale change.
> > Isn't Ogg Theora working on wavelet compression for imagery?
> Do you mean Tarkin? That's wavelet compression for video. Is it usable
> for still images too?
No, it's not appropriate for GIS. Wavelets can be highly tunable to the
application at hand. We want more of what wavelets have to offer than
I did notice that there is an add-on r.wavelet module, but I have not
used it. The backend library seems to be license-free and GPL, IIRC.
Wavelets for GRASS as an imagery format is "pie in the sky". :-\ There
are too many other issues that need attention at the moment.
I'd be interested in what Glynn's opinion is. It may be more trouble
that its worth (we'd need someone dedicated to implementing and
supporting it). However, I do see it becoming increasingly popular at
municipalities who regularly deal with very large imagery sets (10G-1T
sizes) and not being able to support a comparable format is a major
Beyond getting Glynn's input, it's probably a waste of time discussing
it further unless someone stands up and offers their expertise and time
to implement it as an optional format (it is not appropriate for
non-contiguous rasters). Even so, I'd still recommend that person work
on other pressing issues before adding a new imagery format.
Brad Douglas <rez touchofmadness com> KB8UYR/6
Address: 37.493,-121.924 / WGS84 National Map Corps #TNMC-3785
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