org.gcube.dataanalysis.geo.vti.vesselsprocessing

Class VTIBathymetry

java.lang.Object

org.gcube.dataanalysis.geo.vti.vesselsprocessing.VTIBathymetry

public class VTIBathymetry
extends Object

Class for obtaining altimetry and bathymetry values from a netCDF file. Requires the netCDF libraries (see here: http://www.unidata.ucar.edu/software/netcdf-java/documentation.htm) You should use the class in the following way:

   VTIBathymetry bath = new VTIBathymetry("/path/to/bath.nc");   // e.g. gebco_08.nc
   bath.open();                                                  // file must be explicitly opened, this takes a short time, avoid opening it several times
   short value1 = bath.getZ(142.2, 11.35);                       // e.g. Mariana Trench
   short value2 = bath.getZ(0, 0);
   // ...
   bath.close();                                                 // file should be closed when not needed any longer
 

Author:

Frank Loeschau, Terradue Srl.

Field Summary

Fields

Modifier and Type	Field and Description
int	GRID_COLS
int	GRID_ROWS

Constructor Summary

Constructors

Constructor and Description
VTIBathymetry(String filename) Creates an instance of VTIBathymetry with the specified file.

Method Summary

Modifier and Type	Method and Description
void	close() Closes the netCDF file.
short	getZ(double x, double y) Returns the altimetric/bathymetric value of the given geographical coordinates.
short	getZ(Point2D.Double point) Returns the altimetric/bathymetric value of the given geographical coordinates.
short[]	getZ(Point2D.Double[] points) Returns the altimetric/bathymetric values of the given array of geographical coordinates.
static void	main(String[] args) The class can also be used as command-line tool.
void	open() Opens the netCDF file and loads the data array.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

GRID_COLS

public final int GRID_COLS

See Also:

Constant Field Values

GRID_ROWS

public final int GRID_ROWS

See Also:

Constant Field Values

Constructor Detail

VTIBathymetry

public VTIBathymetry(String filename)

Creates an instance of VTIBathymetry with the specified file.

Parameters:

filename - the netCDF filename containing the altimetry/bathymetry data

Method Detail

main

public static void main(String[] args)

The class can also be used as command-line tool. The syntax is:

java org.d4science2.vtivre.VTIBathymetry get x1,y1 [x2,y2 [...]] filename

If only one pair of coordinates is specified, debug information about the calculation is written.

Parameters:

args - the command-line arguments

open

public void open()
          throws IOException

Opens the netCDF file and loads the data array. This operation is somewhat slow and requires the creation of a big object in memory. Ideally, this method is called only once, before the altrimetry/bathymetry values are needed.

Throws:

IOException

close

public void close()
           throws IOException

Closes the netCDF file.

Throws:

IOException

getZ

public short getZ(Point2D.Double point)
           throws IOException

Returns the altimetric/bathymetric value of the given geographical coordinates. The value derives from the corresponding cell in the coordinate grid (120 x 120 cells per degree). If a coordinate is close to the cell border (< 0.1 * arc cell size), the result value is averaged with the value from the adjacent cell.

Parameters:

point - the geographical coordinates (x = longitude value (-180 to 180), y = latitude value (-90 to 90))

Returns:

the altimetric/bathymetric value for the coordinate (in meters)

Throws:

IOException - if the netCDF variable z could not been read

getZ

public short[] getZ(Point2D.Double[] points)
             throws IOException

Returns the altimetric/bathymetric values of the given array of geographical coordinates. The value derives from the corresponding cell in the coordinate grid (120 x 120 cells per degree). If a coordinate is close to the cell border (< 0.1 * arc cell size), the result value is averaged with the value from the adjacent cell.

Parameters:

points - array of geographical coordinates (x = longitude value (-180 to 180), y = latitude value (-90 to 90))

Returns:

an array of the same shape as points, containing the altimetric/bathymetric value for the coordinate (in meters)

Throws:

IOException - if the netCDF variable z could not been read

getZ

public short getZ(double x,
                  double y)
           throws NullPointerException,
                  IOException

Returns the altimetric/bathymetric value of the given geographical coordinates. The value derives from the corresponding cell in the coordinate grid (120 x 120 cells per degree). If a coordinate is close to the cell border (< 0.1 * arc cell size), the result value is averaged with the value from the adjacent cell.

Parameters:

x - longitude coordinate (-180 to 180)

y - latitude coordinate (-90 to 90)

Returns:

the altimetric/bathymetric value for the coordinate (in meters)

Throws:

NullPointerException - if the netCDF file has not been opened or the variable z (containing the altimetry/bathymetry values) is not found

IOException - if the netCDF variable z could not been read