src.gov.nasa.worldwind.util.ElevationsUtil Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of worldwindx Show documentation
Show all versions of worldwindx Show documentation
World Wind is a collection of components that interactively display 3D geographic information within Java applications or applets.
/*
* Copyright (C) 2012 United States Government as represented by the Administrator of the
* National Aeronautics and Space Administration.
* All Rights Reserved.
*/
package gov.nasa.worldwind.util;
import gov.nasa.worldwind.avlist.*;
import gov.nasa.worldwind.data.ByteBufferRaster;
/**
* @author Lado Garakanidze
* @version $Id: ElevationsUtil.java 1171 2013-02-11 21:45:02Z dcollins $
*/
public class ElevationsUtil
{
public static final double DTED_DEFAULT_MISSING_SIGNAL = -32767d;
public static final double SRTM_DEFAULT_MISSING_SIGNAL = -32768d;
public static final double DEM_DEFAULT_MISSING_SIGNAL = -9999d;
protected static final double[] knownMissingSignals = {
DTED_DEFAULT_MISSING_SIGNAL, SRTM_DEFAULT_MISSING_SIGNAL, DEM_DEFAULT_MISSING_SIGNAL
};
/**
* Checks if the value is one of the well-known "nodata" value used in digital elevation model files
* to specify missing areas / voids.
*
* @param value a value to check
* @return TRUE, if the value is one of the well known "nodata" values
*
*/
public static boolean isKnownMissingSignal(Double value)
{
if( null != value )
{
for(double signal : knownMissingSignals )
{
if( value == signal )
return true;
}
}
return false;
}
/**
* Rectify elevation raster. For best performance each elevation raster must have correct parameters and values set.
* The rectify() operation validates that correct Elevation min and max values are set or calculated.
* All values that beyond min/max and voids, must be marked with "Missing Signal" (aka "nodata" value).
*
* @param raster A DataRaster to rectify
* @throws IllegalArgumentException if raster is null
*/
public static void rectify(ByteBufferRaster raster) throws IllegalArgumentException
{
if( null == raster )
{
String msg = Logging.getMessage("nullValue.RasterIsNull");
Logging.logger().finest(msg);
throw new IllegalArgumentException(msg);
}
int width = raster.getWidth();
int height = raster.getHeight();
if( width == 0 || height == 0 )
{
// nothing to do
return;
}
double[] minmax= raster.getExtremes();
if( null == minmax )
{
// nothing to do
return;
}
Double minValue = minmax[0];
Double maxValue = minmax[1];
Double missingDataSignal = AVListImpl.getDoubleValue(raster, AVKey.MISSING_DATA_SIGNAL, null);
// check if the minimum value is one of the well known NODATA values
if (ElevationsUtil.isKnownMissingSignal(minValue)
|| (missingDataSignal != null && missingDataSignal.equals(minValue))
)
{
missingDataSignal = minValue;
raster.setTransparentValue(missingDataSignal);
minmax = raster.getExtremes();
if (null != minmax)
{
minValue = minmax[0];
maxValue = minmax[1];
}
}
BufferWrapper bufferWrapper = raster.getBuffer();
// Allocate a buffer to hold one row of scalar values.
double[] array = new double[width];
boolean needsConversion = false;
double conversionValue = 1d;
if( raster.hasKey(AVKey.ELEVATION_UNIT) )
{
String unit = raster.getStringValue(AVKey.ELEVATION_UNIT);
if( AVKey.UNIT_METER.equalsIgnoreCase(unit) )
{
needsConversion = false;
}
else if( AVKey.UNIT_FOOT.equalsIgnoreCase(unit) )
{
needsConversion = true;
conversionValue = WWMath.convertFeetToMeters(1);
minValue = WWMath.convertFeetToMeters(minValue);
maxValue = WWMath.convertFeetToMeters(maxValue);
raster.setValue(AVKey.ELEVATION_UNIT, AVKey.UNIT_METER);
}
else
{
needsConversion = false;
String msg = Logging.getMessage("generic.UnrecognizedElevationUnit", unit);
Logging.logger().warning(msg);
}
}
boolean rasterHasVoids = false;
for (int j = 0; j < height; j++)
{
bufferWrapper.getDouble( j * width, array, 0, width );
boolean commitChanges = false;
for (int i = 0; i < width; i++)
{
double value = array[i];
if( null != missingDataSignal && value == missingDataSignal )
{
rasterHasVoids = true;
}
else
{
if( needsConversion )
{
value *= conversionValue;
commitChanges = true;
array[i] = value;
}
if( value < minValue || value > maxValue )
{
rasterHasVoids = true;
if( null != missingDataSignal)
{
array[i] = missingDataSignal;
commitChanges = true;
}
}
}
}
if( commitChanges )
bufferWrapper.putDouble( j * width, array, 0, width );
}
if( rasterHasVoids )
{
if( missingDataSignal != null )
raster.setValue(AVKey.MISSING_DATA_SIGNAL, missingDataSignal );
}
else
{
raster.removeKey(AVKey.MISSING_DATA_SIGNAL);
}
raster.setValue(AVKey.ELEVATION_MIN, minValue);
raster.setValue(AVKey.ELEVATION_MAX, maxValue);
}
}