Hello Pieter,
If you just want to get all pixel values you are probably better off
working directly with the backing image and using a JAI iterator to
sample it. That way you are not incurring the overhead of
geo-referencing conversions that you don't need.
RenderedImage image = myCoverage.getRenderedImage();
RectIter iter = RectIterFactory.create(image, null); // creates
iterator for whole image
do {
do {
double value = iter.getSampleDouble(); // getting value from
default band 0
// do something with value
...
} while (!iter.nextPixelDone());
iter.startPixels();
} while (!iter.nextLineDone());
Michael
On 22 June 2011 19:29, pieterjlouw <[email protected]> wrote:
> Yep, GridGeometry does the trick!
>
> The following code goes with that previous code I adopted from Michael
> (above) and noticed it is very slow when I try to return values for each
> pixel in the 3601x3601 AsterDEM. The fact that this same GeoTiff can be
> rendered and displayed in a couple of seconds in examples like ImageLab.java
> on GeoTools tells me that my code is inefficient.
>
> Does anyone have suggestions on streamlining the code so that it doesn't
> take ~47 minutes for decoding the entire DEM...? (The AsterDEM contains 3601
> x 3601 pixels...)
>
> ====================================
> Conversion Code:
> ----------------------------------------------
>
> System.out.println("Start: " + DateTime());
>
> for (int i=gridBounds.getLow(0); i<gridBounds.getHigh(0) + 1; i++) {
> for (int j=gridBounds.getLow(1); j<gridBounds.getHigh(1) + 1;
> j++) {
>
> dp = cov.getGridGeometry().gridToWorld(new
> GridCoordinates2D(i, j));
> cov.evaluate(dp, values);
>
> lon = dp.getCoordinate()[0];
> lat = dp.getCoordinate()[1];
> double ht = values[0];
>
> if (i == 100 && j == 0) System.out.println("line 100: " +
> DateTime());
> if (i == 500 && j == 0) System.out.println("line 500: " +
> DateTime());
> if (i == 1000 && j == 0) System.out.println("line 1000: " +
> DateTime());
> }
> }
> System.out.println("Finish: " + DateTime());
>
> ==================================================
> Run Output:
> ----------------------------------------------------------------
>
> Building tutorial 0.0.1-SNAPSHOT
> ------------------------------------------------------------------------
> [resources:resources]
> Using 'UTF-8' encoding to copy filtered resources.
> skip non existing resourceDirectory C:\Pieter\Development\GeoTools
> AsterDEM\AsterDEM\src\main\resources
>
> [compiler:compile]
> Nothing to compile - all classes are up to date
>
> [exec:exec]
> grid bounds: GeneralGridEnvelope[0..3600, 0..3600]
> world bounds: Envelope2D[(20.999861111111112, -11.00013888888889),
> (22.000138888888888, -9.99986111111111)]
> num bands: 1
> value at DirectPosition2D[21.5, -10.5] is 1105.0
>
>
> Start: 22-06-2011 10:59:24
> line 100: 22-06-2011 11:00:44
> line 500: 22-06-2011 11:05:56
> line 1000: 22-06-2011 11:12:26
>
> ============================================================
>
> --
> View this message in context:
> http://osgeo-org.1803224.n2.nabble.com/Reading-ASTER-DEM-Data-tp3728702p6503540.html
> Sent from the geotools-gt2-users mailing list archive at Nabble.com.
>
> ------------------------------------------------------------------------------
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------------------------------------------------------------------------------
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Installation's a snap, and flexible recovery options mean your data is safe,
secure and there when you need it. Data protection magic?
Nope - It's vRanger. Get your free trial download today.
http://p.sf.net/sfu/quest-sfdev2dev
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