El 13/03/13 10:14, Andrea Aime escribió:
On Wed, Mar 13, 2013 at 9:47 AM, PabloDR <pablo.labor...@gmail.com
<mailto:pablo.labor...@gmail.com>> wrote:
I've done something similar to get noData, min and max values:
private static SortedSet<Double> removeNoDataFromArray(double[]
data, Double NoData){
SortedSet<Double> set = CollectionFactory.sortedSet();
Double[] array = ArrayUtils.toObject(data);
set.addAll(Arrays.asList(array));
while (set.remove(NoData));
return set;
}
private static double[] getDataFromCoverage(GridCoverage2D
coverage){
Raster raster = coverage.getRenderedImage().getData();
double data[] = new
double[raster.getHeight()*raster.getWidth()];
data = raster.getPixels(raster.getMinX(), raster.getMinY(),
raster.getWidth(), raster.getHeight(), data);
return data;
}
public static double getMaxValue(GridCoverage2D coverage){
Double NoData = getNoDataValue(coverage);
double data[] = getDataFromCoverage(coverage);
SortedSet<Double> set = removeNoDataFromArray(data, NoData);
return set.last();
}
public static double getMinValue(GridCoverage2D coverage){
Double NoData = getNoDataValue(coverage);
double data[] = getDataFromCoverage(coverage);
SortedSet<Double> set = removeNoDataFromArray(data, NoData);
return set.first();
}
public static Double getNoDataValue(GridCoverage2D coverage){
Double NoData = (Double)coverage.getProperty("GC_NODATA");
return NoData;
}
I can see them being added either to a utility class or to
GridCoverage2D itself,
but implemented this way they cannot be added to GeoTools:
- they have no support for multiband coverages
- they read all the coverage in memory, which is a no-go, some readers
easily
handle coverages of hundreds of gigabytes in size... this has to be
implemented
either as a JAI operation (a NODATA aware Extrema), or using tile
oriented
access to the RenderedImage inside the coverage, so that only a
chunk of the data at a time is
loaded in memory
I mean, geotools base library should implement the methods getMax,
getMin and getNoDataValue, but not the methods I wrote, because, in
fact, these methods are incomplete and runs well only in a few ways.
Thanks Andrea.
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