org.ka2ddo.yaac.srtm

Class SRTMTile

java.lang.Object

org.ka2ddo.yaac.srtm.SRTMTile

public class SRTMTile
extends java.lang.Object

This class defines the in-memory cache entry for one SRTM binary tile (1 arc-second or 3 arc-second variations).

Author:

Andrew Pavlin, KA2DDO

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String[]	DEM_SRC_CODES Mappings of NASADEM source code byte values to names of data sources as defined here.
short	maxGradient The maximum change in elevation between any two adjacent cells, in meters.
short	maxZ The highest elevation in this tile, in meters.
int	minLat The integer latitude (in whole degrees) of the southwest corner of the tile.
int	minLon The integer longitude (in whole degrees) of the southwest corner of the tile.
short	minZ The lowest elevation in this tile, in meters.
static short	NO_CELL Reserved value indicating the elevation at the specified grid point is unknown.
short	numCellsPerAxis The number of grid cells + 1 in this tile.
byte[]	sources If an associated .num file is provided with the .hgt file, this contains the code numbers identifying all unique sources of the elevation data in this tile.
short[][]	zCells The two-dimensional grid of regularly spaced elevation values (separated by 1 degree / (numCellsPerAxis - 1)), The first index is along the latitude axis, with index 0 at the southernmost latitude, and the second index is along the longitude axis, with index 0 at the westernmost longitude.

Constructor Summary

Constructors

Constructor and Description
SRTMTile()

Method Summary

Modifier and Type	Method and Description
int	getSize() Report the amount of memory consumed by this tile.
void	loadGzip(java.io.File srtmFile, int lat, int lon) Read a tile file into this in-memory data structure
void	loadZip(java.io.File srtmFile, int lat, int lon) Read a zipped tile file into this in-memory data structure
void	setCoord(SRTMTileId id) Set the lower-left corner coordinates of this tile.
java.lang.String	toString() Returns a string representation of the object.

Methods inherited from class java.lang.Object

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

Field Detail

minLat

public int minLat

The integer latitude (in whole degrees) of the southwest corner of the tile.

minLon

public int minLon

The integer longitude (in whole degrees) of the southwest corner of the tile.

numCellsPerAxis

public short numCellsPerAxis

The number of grid cells + 1 in this tile. For 3-arc-second tiles, this will be 1201.

maxGradient

public short maxGradient

The maximum change in elevation between any two adjacent cells, in meters.

minZ

public short minZ

The lowest elevation in this tile, in meters.

maxZ

public short maxZ

The highest elevation in this tile, in meters.

zCells

public short[][] zCells

The two-dimensional grid of regularly spaced elevation values (separated by 1 degree / (numCellsPerAxis - 1)), The first index is along the latitude axis, with index 0 at the southernmost latitude, and the second index is along the longitude axis, with index 0 at the westernmost longitude.

sources

public byte[] sources

If an associated .num file is provided with the .hgt file, this contains the code numbers identifying all unique sources of the elevation data in this tile.

DEM_SRC_CODES

public static final java.lang.String[] DEM_SRC_CODES

Mappings of NASADEM source code byte values to names of data sources as defined here.

NO_CELL

public static final short NO_CELL

Reserved value indicating the elevation at the specified grid point is unknown.

See Also:

Constant Field Values

Constructor Detail

SRTMTile

public SRTMTile()

Method Detail

toString

public java.lang.String toString()

Returns a string representation of the object.

Overrides:

toString in class java.lang.Object

Returns:

a string representation of the object.

setCoord

public void setCoord(SRTMTileId id)

Set the lower-left corner coordinates of this tile.

Parameters:

id - SRTMTileId to obtain coordinates from

loadZip

public void loadZip(java.io.File srtmFile,
                    int lat,
                    int lon)
             throws java.io.IOException

Read a zipped tile file into this in-memory data structure

Parameters:

srtmFile - File object describing the file to read

lat - latitude in whole degrees North for the tile

lon - longitude in whole degrees East for the tile

Throws:

java.io.IOException - if the file could not be successfully read for any reason

loadGzip

public void loadGzip(java.io.File srtmFile,
                     int lat,
                     int lon)
              throws java.io.IOException

Read a tile file into this in-memory data structure

Parameters:

srtmFile - File object describing the file to read

lat - latitude in whole degrees North for the tile

lon - longitude in whole degrees East for the tile

Throws:

java.io.IOException - if the file could not be successfully read for any reason

getSize

public int getSize()

Report the amount of memory consumed by this tile. Can be used to dynamically size the cache of SRTMTiles to prevent heap overload. This estimate is based on the behavior of 32-bit JVM memory management.

Returns:

estimated heap consumption of this SRTMTile and its sub-objects in bytes