Hi again,
see my response bellow:
El día 5 de octubre de 2009 22:24, Simone Giannecchini
<[email protected]> escribió:
> Ciao Cesar,
[SNIP]
> This is probably the worst way to work with a PlanarImage. I dag once
> those bindings and I told Victor that he was loading everything into
> memory doing that. Actually not only that, that code cobbles the
> original raster into a single untiled raster in memory, performing a
> full copy! Rather inefficient I would say :-)
[SNIP]
> the goal is to use iterators to do the processing, or anyway to do it
> tile by tile in order to avoid copies and/or loading everything into
> memory.
>
> Simone.
Thanks a lot for the links and suggestions. I've read this
documentation, and if I've correctly understood there are two
different possible approaches:
- Using iterators
- Using tiles
I've tried both of them, but I've also found an error in the process.
As I'm a JAI and GeoTools beginner, I'm not sure if there is a problem
in the driver or I misunderstood documentation.
I paste relevant code bellow:
----------------- ITERATOR APPROACH -----
ArcGridFormat agf = new ArcGridFormat();
GridCoverageReader reader = agf.getReader(file);
GridCoverage2D gc = (GridCoverage2D) reader.read(null);
PlanarImage img = (PlanarImage) gc.geophysics(true).getRenderedImage();
RectIter iter = RectIterFactory.create(img, null);
iter.startBands();
while (!iter.finishedBands()) {
iter.startLines();
while (!iter.finishedLines()) {
iter.startPixels();
while (!iter.finishedPixels()) {
int value = iter.getSample();
if (value!=9999 && value!=-9999) {
System.out.println(value);
}
iter.nextPixel();
}
iter.nextLine();
}
iter.nextBand();
}
-----------------
After some time running, I get the following exception:
java.lang.IllegalArgumentException: pos < flushedPos!
at
it.geosolutions.imageio.stream.input.FileImageInputStreamExtImpl.seek(FileImageInputStreamExtImpl.java:285)
at
it.geosolutions.imageio.plugins.arcgrid.raster.AsciiGridRaster.readRaster(AsciiGridRaster.java:578)
at
it.geosolutions.imageio.plugins.arcgrid.AsciiGridsImageReader.readRaster(AsciiGridsImageReader.java:659)
at
it.geosolutions.imageio.plugins.arcgrid.AsciiGridsImageReader.read(AsciiGridsImageReader.java:520)
at
com.sun.media.jai.imageioimpl.ImageReadOpImage.computeTile(ImageReadOpImage.java:697)
at
com.sun.media.jai.util.SunTileScheduler.scheduleTile(SunTileScheduler.java:904)
at javax.media.jai.OpImage.getTile(OpImage.java:1129)
at javax.media.jai.RenderedOp.getTile(RenderedOp.java:2257)
at etclusi.tests.gt.TestArcGrid2.main(TestArcGrid2.java:48)
I have also tried with tiles, but I get the same error.
I assume in this code that the tiles are automatically managed by the
PlanarImage and are not kept in memory (except the tiles that I ask
for and I keep referencing), but I'm not sure if this assumption is
correct...
---------------------- TILES APPROACH --------------------
ArcGridFormat agf = new ArcGridFormat();
GridCoverageReader reader = agf.getReader(file);
GridCoverage2D gc = (GridCoverage2D) reader.read(null);
PlanarImage img = (PlanarImage) gc.geophysics(true).getRenderedImage();
for (int j=img.getMinTileY(), maxTileY = img.getMaxTileY();
j<=maxTileY ; j++) {
for (int i=img.getMinTileX(), maxTileX = img.getMaxTileX();
i<=maxTileX; i++) {
Raster tile = img.getTile(i, j);
for (int y=tile.getMinY(), maxY = tile.getHeight()+y;
y<maxY; y++) {
for (int x=tile.getMinX(), maxX =
tile.getWidth()+x; x<maxX; x++) {
int value = tile.getSample(x, y, 0); //
assume band 0
System.out.println("x: "+x+",
y: "+y+", value: "+ value);
}
}
}
}
-------------------------------
Again, after a while:
java.lang.IllegalArgumentException: pos < flushedPos!
at
it.geosolutions.imageio.stream.input.FileImageInputStreamExtImpl.seek(FileImageInputStreamExtImpl.java:285)
at
it.geosolutions.imageio.plugins.arcgrid.raster.AsciiGridRaster.readRaster(AsciiGridRaster.java:578)
at
it.geosolutions.imageio.plugins.arcgrid.AsciiGridsImageReader.readRaster(AsciiGridsImageReader.java:659)
at
it.geosolutions.imageio.plugins.arcgrid.AsciiGridsImageReader.read(AsciiGridsImageReader.java:520)
at
com.sun.media.jai.imageioimpl.ImageReadOpImage.computeTile(ImageReadOpImage.java:697)
at
com.sun.media.jai.util.SunTileScheduler.scheduleTile(SunTileScheduler.java:904)
at javax.media.jai.OpImage.getTile(OpImage.java:1129)
at javax.media.jai.RenderedOp.getTile(RenderedOp.java:2257)
at etclusi.tests.gt.TestArcGrid2.main(TestArcGrid2.java:70)
So I don't know if there is an error in my code, or it is a problem
with the driver.
By the way, I've also seen all these methods "getDataBlock"
(deprecated), "evaluate"... in the GridCoverage interface, and I
wonder which is the preferred/intended way to access the pixel values
in GeoTools.
Best regards,
César Martínez Izquierdo
--
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César Martínez Izquierdo
GIS developer
- - - - - - - - - - - - - - - - - - - -
ETC-LUSI: http://etc-lusi.eionet.europa.eu/
Universitat Autònoma de Barcelona (SPAIN)
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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