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Re: [udig-devel] JGrass goes UDig IRC document
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Ciao guys,
I have read the document myself and I have a few
remarks/thoughts/corrections myself:
-----> http://udig.refractions.net/confluence/display/JGRASS/raster (GRASS
raster format section)
I would rephrase the solutions proposed by uDig (who's this guy? :-) )
PROBLEM:
Consuming JGrass Binary format.
SOLUTION 1
If you have read/write software you don't necessarily need to create a
geotools reader/writer you just need to create an adapter from your model to
GridCoverage and pass that to the GridCoverageRenderer.
SOLUTION 2
Write a fully-fledged plugin for GeoTools Coverage package
THOUGHTS
The StreamingRenderer uses Coverage Plugins' Readers to create coverages
when feeding the GridCoverageRender. It does so by providing an envelope and
the requested viewport size to the reader which selects the best availaible
resolution depending on the view's resolution and on the capabilities of the
underlying format in terms of overviews and/or decimation on reading, as
well as tiling.
If we go directly to the GridCoverageRenderer no "external" optimization is
performed and the provided data is processed. This means no overviews and no
decimation.
In this special case (JGrass binary format) we could do subsetting and
decimation on the fly at the reader level as well as intelligent tiling.
JGRass binary format has stripes like striped geotiff so in the end what
you could do is loading only the stripes you need and of each stripe only
the needed part possibly with a bit of multithreading (undelrying
JAI-ImageIO framework comes with that by almost by default)
If we develop a plugin there also are various tricks that we can use to
speed things up
External overviews - we add (it's easy) support for external overviews
like in gdal - this requires to preprocess the raster
Internal pyramid - (not as easy) use an in-memory pyramid, Simboss coded
2 for geotif but never tested enough to release it can be very fast but
it is still unstable
Of course this approach has a cost in term of time which is not negligible,
hence I would recommed it except in the case of qorking under very
sstringent deadlines.
If you wrap your architecture behind a GridCoverage2D you might loose some
performance gain ( in some cases, with big dataset you would get awful
performances)
and you might waste a lot of time trying to actually mimic the
GridCoverage2D. IMHO the latter solution could be much faster but could also
generate some (quite some? ) problems
later on. It would great to investigate this path a bit deeper, especially
if this integration needs to be done very quickly.
----->http://udig.refractions.net/confluence/display/JGRASS/datamodel
PROBLEM:
Integrating an existing 3D data model like VisAD in uDig.
SOLUTION 1
Sorry, no time yet to think about an integration.
Cheers,
Simone.
----- Original Message -----
From: Jesse Eichar
To: andrea.antonello@xxxxxxxxx ; User-friendly Desktop Internet GIS
Sent: Monday, February 05, 2007 6:52 PM
Subject: Re: [udig-devel] JGrass goes UDig IRC document
I'm looking over the web page right now. So far this is what I've found
that is not correct:
http://udig.refractions.net/confluence/display/JGRASS/glossary:
- The information about projections seems to backwards you have uDig listed
as using proj.
- the Model/Application->Operation row is not very clear. I think I
understand it but others probably won't
http://udig.refractions.net/confluence/display/JGRASS/licensing
- As we discussed on another email. It looks like we can ship uDig with
Grass it is more the SDK that is impacted by the licensing issues.
http://udig.refractions.net/confluence/display/JGRASS/raster
- Looks like you got most of the points on topic, well done.
- With regards to filter, it did not seem like a good solution since it will
be obsolete once the SelectionService comes along.
http://udig.refractions.net/confluence/display/JGRASS/mainengine
Looks good.
http://udig.refractions.net/confluence/display/JGRASS/datamodel
- I don't know VISAD but since uDig is designed to integrate multiple
technologies it seems likely that you could use VISAD for your 3D processing
http://udig.refractions.net/confluence/display/JGRASS/grasscompatibility
- Also good.
For the main page, How do you want me to answer your questions?
Jesse
On 3-Feb-07, at 3:12 AM, Andrea Antonello wrote:
I finished to set up the first draft of what was discussed in the IRC
meeting. Could the main involved persons please review that quickly and
check if we understood each other? (Jesse, Jody, Simone)
http://udig.refractions.net/confluence/display/JGRASS/Home
Please let me know your thoughts,
I will then have to find a starting point.
Andrea
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User-friendly Desktop Internet GIS (uDig)
http://udig.refractions.net
http://lists.refractions.net/mailman/listinfo/udig-devel
_______________________________________________
User-friendly Desktop Internet GIS (uDig)
http://udig.refractions.net
http://lists.refractions.net/mailman/listinfo/udig-devel
