working with custom tilecache

[jai-interest-2]

Hi folks,

I've been working on a custom tile cache class that swaps tiles between memory and disk storage.

At the risk of displaying my ignorance, how do I force JAI operations to use my custom cache ?

I have a little test program that creates an image using the "constant" operation and I am trying to have it use my custom cache...

        DiskBasedTileCache cache = new DiskBasedTileCache(cacheParams);

        ImageLayout layout = new ImageLayout();
        layout.setTileWidth(TILE_WIDTH);
        layout.setTileHeight(TILE_WIDTH);

        Map<RenderingHints.Key, Object> imgParams = new HashMap<RenderingHints.Key, Object>();
        imgParams.put(JAI.KEY_IMAGE_LAYOUT, layout);
        imgParams.put(JAI.KEY_TILE_CACHE, cache);

        RenderingHints hints = new RenderingHints(imgParams);

        ParameterBlockJAI pb = new ParameterBlockJAI("constant");
        pb.setParameter("width", (float)IMAGE_WIDTH);
        pb.setParameter("height", (float)IMAGE_HEIGHT);
        pb.setParameter("bandValues", new Double[]{0d, 1d, 2d});

        RenderedOp op = JAI.create("constant", pb, hints);

        // force computation
        Raster tile = op.getTile(1, 1);

The image is produced correctly but my cache is not used. I must be missing something obvious and I'd be very grateful for any tips.

cheers
Michael

P.S. This new cache, if it ever works, will be available as part of the jai-tools project: http://code.google.com/p/jai-tools/
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[Bob Deen]

The tile cache saves the *inputs* to an operation, not the outputs.
"constant" has no inputs, so the cache does not get used.  If you put
another op in the chain after "constant", it should get used.

You can also set the global tile cache (used for all ops) via the JAI
object, but I don't recall the specific call offhand.

-Bob

jai-interest@... wrote:

> Hi folks,
>
> I've been working on a custom tile cache class that swaps tiles between memory and disk storage.
>
> At the risk of displaying my ignorance, how do I force JAI operations to use my custom cache ?
>
> I have a little test program that creates an image using the "constant" operation and I am trying to have it use my custom cache...
>
>         DiskBasedTileCache cache = new DiskBasedTileCache(cacheParams);
>
>         ImageLayout layout = new ImageLayout();
>         layout.setTileWidth(TILE_WIDTH);
>         layout.setTileHeight(TILE_WIDTH);
>
>         Map<RenderingHints.Key, Object> imgParams = new HashMap<RenderingHints.Key, Object>();
>         imgParams.put(JAI.KEY_IMAGE_LAYOUT, layout);
>         imgParams.put(JAI.KEY_TILE_CACHE, cache);
>
>         RenderingHints hints = new RenderingHints(imgParams);
>
>         ParameterBlockJAI pb = new ParameterBlockJAI("constant");
>         pb.setParameter("width", (float)IMAGE_WIDTH);
>         pb.setParameter("height", (float)IMAGE_HEIGHT);
>         pb.setParameter("bandValues", new Double[]{0d, 1d, 2d});
>
>         RenderedOp op = JAI.create("constant", pb, hints);
>
>         // force computation
>         Raster tile = op.getTile(1, 1);
>
> The image is produced correctly but my cache is not used. I must be missing something obvious and I'd be very grateful for any tips.
>
> cheers
> Michael
>
> P.S. This new cache, if it ever works, will be available as part of the jai-tools project: http://code.google.com/p/jai-tools/
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>
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>
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[jai-interest-2]

Oh I see - thanks very much Bob !

<slaps forehead>

I have a use case where I am converting vector data to raster. Data are written to the output image by drawing into it with Graphics2D methods.  In such a case is there any commonly used approach to handle a very large output image as tiles ?

The only thing that occurs to me straight off is to sub-class TiledImage.

cheers
Michael
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[jai-interest-2]

trying to work out how to flag correct reply - don't see any buttons or links on replies with either safari or firefox
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[jai-interest-2]

Oh I see - thanks very much Bob !

<slaps forehead>

I have a use case where I am converting vector data to raster. Data are written to the output image by drawing into it with Graphics2D methods.  In such a case is there any commonly used approach to handle a very large output image as tiles ?

The only thing that occurs to me straight off is to sub-class TiledImage.

cheers
Michael
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[Simone.Giannecchini]

Ciao Michael,
please, read below....
-------------------------------------------------------
Ing. Simone Giannecchini
GeoSolutions S.A.S.
Owner - Software Engineer
Via Carignoni 51
55041  Camaiore (LU)
Italy

phone: [phone]
fax:      [phone]
mob:    [phone]


http://www.geo-solutions.it
http://geo-solutions.blogspot.com/
http://simboss.blogspot.com/
http://www.linkedin.com/in/simonegiannecchini

-------------------------------------------------------



On Thu, Jul 9, 2009 at 6:45 AM, <jai-interest@...> wrote:
> Oh I see - thanks very much Bob !
>
> <slaps forehead>
>
> I have a use case where I am converting vector data to raster. Data are written to the output image by drawing into it with Graphics2D methods.  In such a case is there any commonly used approach to handle a very large output image as tiles ?
>
> The only thing that occurs to me straight off is to sub-class TiledImage.

That's the same thing I would do. TiledImage and TiledImageGraphics
should give what you need. Specifically, if you wrap you tilecache as
a WritableRenderedImage using TiledImage as a guideline you should be
able to adapt quite easily a TiledImageGraphics (its a JAI class)
which would allow you to perform Java2D operations on very large
images, not bound memory bound.


Ciao,
Simone.

>
> cheers
> Michael
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[jai-interest-2]

> Specifically, if you wrap you tilecache as
> a WritableRenderedImage using TiledImage as a
> guideline you should be
> able to adapt quite easily a TiledImageGraphics (its
> a JAI class)
> which would allow you to perform Java2D operations on
> very large
> images, not bound memory bound.
>

Excellent - thanks very much Simone !

Also, based on Bob's advice (above) I added another node to the chain in my demo program (see first post) so that I now have:

"constant" operation -> op1 -> "multiplyconst" operation -> op2

My custom cache is now being used (hurray) and the tiles have the data for the final OpImage in the chain, op2. From Bob's post I'd got the idea that outputs weren't cached. I obviously need to study how JAI chains work in more detail.

Thanks again
Michael
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[Bob Deen]

Some operators modify the source tiles in-place, after taking ownership
of them, of course.  It's quite possible that's what multiplyconst does,
as that's far more efficient than copying everything.  I don't recall
the details
of this process, but that's probably what's happening.  You keep picking
special-case ops!!  ;-)

-Bob

jai-interest@... wrote:

>> Specifically, if you wrap you tilecache as
>> a WritableRenderedImage using TiledImage as a
>> guideline you should be
>> able to adapt quite easily a TiledImageGraphics (its
>> a JAI class)
>> which would allow you to perform Java2D operations on
>> very large
>> images, not bound memory bound.
>>
>
> Excellent - thanks very much Simone !
>
> Also, based on Bob's advice (above) I added another node to the chain in my demo program (see first post) so that I now have:
>
> "constant" operation -> op1 -> "multiplyconst" operation -> op2
>
> My custom cache is now being used (hurray) and the tiles have the data for the final OpImage in the chain, op2. From Bob's post I'd got the idea that outputs weren't cached. I obviously need to study how JAI chains work in more detail.
>
> Thanks again
> Michael
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[jai-interest-2]

> You keep picking special-case ops!!  ;-)
>

I seem to, but at least it's forcing me to think more :-)

A first attempt at a disk and memory backed tile cache is described here...
http://code.google.com/p/jai-tools/wiki/UtilsTileCache

You can browse or download the source code from the site.  There are also some unit tests and a small demo program for the tile cache.

I'm sure there will be bugs to fix and much room for improvement in design and performance so I'd appreciate any comments from folks here.

cheers
Michael
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[jai-interest-2]

Hi folks,

I've just improved (I hope) the operation of the disk and memory backed tile cache class that forms part of the jai-tools project. A brief description is here:
http://code.google.com/p/jai-tools/wiki/UtilsTileCache

You can browse the source code at that site and/or download it with subversion.

Any comments, bug reports etc much appreciated.

cheers
Michael
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