In reply to my own query, I ended up doing this to get the max value.
import org.jaitools.numeric.SampleStats;
import java.awt.image.Raster;
import org.apache.commons.lang3.ArrayUtils;
.
.
.
Raster raster = coverage.getRenderedImage().getData();
double[] data = new double[raster.getHeight()*raster.getWidth()];
raster.getSamples(raster.getMinX(),
raster.getMinY(),
raster.getWidth(),
raster.getHeight(), 0, data);
System.out.println(SampleStats.max(ArrayUtils.toObject(data),
true));
It works, but still wondering if there is a neater way.
- Lauchlin
-----
"The thing's hollow—it goes on forever—and—oh my God—*it's full of stars!*"
On 15 February 2013 15:06, Lauchlin Wilkinson <[email protected]> wrote:
> Hi,
>
> I'm using geotools 8.1 (with a maven project), and am trying to get the
> Minimum and Maximum values for a the single band that is contained in a
> file.
>
> The code I am using is:
>
> File file = new File("/home/xxx/grid.asc");
> AbstractGridFormat format = GridFormatFinder.findFormat(file);
> reader = format.getReader(file);
>
> GridCoverage2D coverage = reader.read(null);
>
> System.out.println("Num Dimensions: " +
> coverage.getNumSampleDimensions());
>
> System.out.println("Min value: " +
> coverage.getSampleDimension(0).getMinimumValue());
> System.out.println("Max value: " +
> coverage.getSampleDimension(0).getMaximumValue());
>
> I know the max value is 1739, the min value is 1 and the NODATA value is
> -99999 by inspecting the grid in SAGA but the above code outputs:
>
> Num Dimensions: 1
> Min value: -99999.0
> Max value: -99999.0
>
> I have also tried using:
>
> NumberRange range = coverage.getSampleDimension(0).getRange();
>
> System.out.println(coverage.getSampleDimension(0).getSampleDimensionType().identifier());
> System.out.println("Min value: " + range.getMinimum());
> System.out.println("Max value: " + range.getMaximum());
>
> But this also outputs the incorrect values:
>
> CV_64BIT_REAL
> Min value: -99999.0
> Max value: -99999.0
>
> When displaying the map with a ColorMap it does show correctly so the
> above output is confusing. Am I using the correct methods or is there
> another way I could easily obtain the min/max without scanning the whole
> file? Is this just a limitation of ascii file format?
>
> Any help would be greatly appreciated. I hope I have provided enough
> detail.
>
> Thanks,
>
> Lauchlin
>
>
>
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