com.bbn.openmap.layer.dted
Class DTEDFrameCache

java.lang.Object
  com.bbn.openmap.util.cacheHandler.CacheHandler
      com.bbn.openmap.layer.dted.DTEDFrameCache

All Implemented Interfaces:

PropertyConsumer

public class DTEDFrameCache
extends CacheHandler
implements PropertyConsumer

The DTEDFrameCache is an object that retrieves DTED paths, frames or elevation values, given a latitude, longitude and dted level. It maintains a collection of the frames it has already used for quicker access later. The size of the cache is user-determined, and the cache also relies on user provided paths to the dted directory, which is the top level directory in a dted file structure. The paths are provided in a String array, so you can have data in different places on a system, including a CDROM drive.

Field Summary

protected java.lang.String[]	dtedDirPaths An array of strings representing data directory paths.
static java.lang.String	DTEDFrameCacheSizeProperty
static java.lang.String	DTEDPathsProperty
static int	MAX_DTED_LEVEL The maximum DTED level to check for data, given a lat/lon and a path to a dted data directory.
static int	NO_DATA The elevation value returned if there is no data at a lat/lon.
protected int	numXSubframes Number of subframes used by each frame.
protected int	numYSubframes Number of subframes used by each frame.
protected java.lang.String	propertyPrefix

Fields inherited from class com.bbn.openmap.util.cacheHandler.CacheHandler

DEFAULT_MAX_CACHE_SIZE, logger, logicalClock, objs

Fields inherited from interface com.bbn.openmap.PropertyConsumer

EditorProperty, initPropertiesProperty, LabelEditorProperty, ScopedEditorProperty

Constructor Summary

DTEDFrameCache()

DTEDFrameCache(java.lang.String[] dtedPaths, int max_size)
Create the cache with paths to search for frames, and the maximum number of frames to keep on hand.

Method Summary

java.lang.String	findFileName(double lat, double lon, int level) A utility to find the path to a dted file, given a lat, lon and a dted level.
protected java.lang.String	findFileName(java.lang.String[] searchPaths, java.lang.String partialFile) Method to check the searchPaths for a file.
DTEDSubframedFrame	get(double lat, double lon, int level) Return The Dted Frame, Given A Lat, Lon And Dted Level.
int	getElevation(float lat, float lon) Return the elevation of a lat/lon point, in meters.
short[][]	getElevations(EqualArc proj, int dtedLevel) Return the two-dimensional matrix of elevation posts (heights) representing coverage of a given geographical rectangle.
short[][]	getElevations(float ullat, float ullon, float lrlat, float lrlon, int dtedLevel) Return the two-dimensional matrix of elevation posts (heights) representing coverage of a given geographical rectangle.
protected short[][]	getElevations(float ullat, float ullon, float lrlat, float lrlon, int dtedLevel, DTEDSubframedFrame refFrame) Return the two-dimensional matrix of elevation posts (heights) representing coverage of a given geographical rectangle.
java.util.Properties	getProperties(java.util.Properties props) PropertyConsumer method.
java.util.Properties	getPropertyInfo(java.util.Properties props) PropertyConsumer method.
java.lang.String	getPropertyPrefix() PropertyConsumer method.
CacheObject	load(java.lang.Object key) Load a dted frame into the cache, based on the path of the frame as a key.
static void	main(java.lang.String[] args)
void	resizeCache(int max_size) This version of resizeCache is for screen size changes, where the number of frames kept on hand in the cache must change, but the images themselves don't have to because the pixel/posting spacing hasn't changed in the projection.
void	resizeCache(int max_size, int num_x_subframes, int num_y_subframes) This version of resizeCache is for projection changes, where the post/pixel spacing of the images has changed, and the images need to be rebuilt.
void	setDtedDirPaths(java.lang.String[] paths) Set the data paths.
void	setProperties(java.util.Properties props) PropertyConsumer method.
void	setProperties(java.lang.String prefix, java.util.Properties props) PropertyConsumer method.
void	setPropertyPrefix(java.lang.String prefix) PropertyConsumer method.

Methods inherited from class com.bbn.openmap.util.cacheHandler.CacheHandler

clear, get, getCacheSize, listIterator, replaceLeastUsed, resetCache, resetCache, searchCache

Methods inherited from class java.lang.Object

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

Field Detail

NO_DATA

public static final int NO_DATA

The elevation value returned if there is no data at a lat/lon.

See Also:

Constant Field Values

MAX_DTED_LEVEL

public static final int MAX_DTED_LEVEL

The maximum DTED level to check for data, given a lat/lon and a path to a dted data directory.

See Also:

Constant Field Values

dtedDirPaths

protected java.lang.String[] dtedDirPaths

An array of strings representing data directory paths.

numXSubframes

protected int numXSubframes

Number of subframes used by each frame. Calculated by the DTEDCacheHandler when it is given a projection.

numYSubframes

protected int numYSubframes

Number of subframes used by each frame. Calculated by the DTEDCacheHandler when it is given a projection.

DTEDPathsProperty

public static final java.lang.String DTEDPathsProperty

See Also:

Constant Field Values

DTEDFrameCacheSizeProperty

public static final java.lang.String DTEDFrameCacheSizeProperty

See Also:

Constant Field Values

propertyPrefix

protected java.lang.String propertyPrefix

Constructor Detail

DTEDFrameCache

public DTEDFrameCache()

DTEDFrameCache

public DTEDFrameCache(java.lang.String[] dtedPaths,
                      int max_size)

Create the cache with paths to search for frames, and the maximum number of frames to keep on hand. Assumes the paths given are for level 0 and 1 data.

Parameters:

dtedPaths - path to the level 0 and level 1 dted directories

max_size - max number of frames to keep in the cache..

Method Detail

setDtedDirPaths

public void setDtedDirPaths(java.lang.String[] paths)

Set the data paths.

Parameters:

paths - paths to the dted level 0 and 1 directories.

findFileName

public java.lang.String findFileName(double lat,
                                     double lon,
                                     int level)

A utility to find the path to a dted file, given a lat, lon and a dted level. Assumes that paths have been given to the cache. Lat/lons in decimal degrees.

Parameters:

lat - latitude of point

lon - longitude of point

level - the dted level wanted (0, 1, 2, 3)

Returns:

complete path to file with lat/lon.

findFileName

protected java.lang.String findFileName(java.lang.String[] searchPaths,
                                        java.lang.String partialFile)

Method to check the searchPaths for a file.

Parameters:

searchPaths - an array of dted root directories

partialFile - the relative pathname of a dted frame file from the dted root.

Returns:

the name of the file, or null if not found.

get

public DTEDSubframedFrame get(double lat,
                              double lon,
                              int level)

Return The Dted Frame, Given A Lat, Lon And Dted Level.

Parameters:

lat - latitude of point

lon - longitude of point

level - the dted level wanted (0, 1, 2)

Returns:

Dted frame.

load

public CacheObject load(java.lang.Object key)

Load a dted frame into the cache, based on the path of the frame as a key.

Specified by:

load in class CacheHandler

Parameters:

key - complete path to the frame, as a string.

Returns:

DTED frame, hidden in a CacheObject.

resizeCache

public void resizeCache(int max_size,
                        int num_x_subframes,
                        int num_y_subframes)

This version of resizeCache is for projection changes, where the post/pixel spacing of the images has changed, and the images need to be rebuilt. The cache size will change based on scale, because more frames are needed for smaller scales. If the number of subframes in either direction is zero, then the resize becomes non-destructive, which means that the frames will not delete their subframes. If the scale of the map changes, then the frame subframe sizes need to be recalculated, and a destructive resizing is necessary.

Parameters:

max_size - the maximum number of frames in the cache.

num_x_subframes - the number of horizontal subframes in each frame.

num_y_subframes - the number of vertical subframes in each frame.

resizeCache

public void resizeCache(int max_size)

This version of resizeCache is for screen size changes, where the number of frames kept on hand in the cache must change, but the images themselves don't have to because the pixel/posting spacing hasn't changed in the projection. The frames already in the cache are re-added to the new cache, if the cache size is increasing. If the cache size is shrinking, then as many as will fit are added to the new cache.

Parameters:

max_size - the new size of the cache.

getElevation

public int getElevation(float lat,
                        float lon)

Return the elevation of a lat/lon point, in meters.

Parameters:

lat - in decimal degrees.

lon - in decimal degrees.

Returns:

elevation in meters.

getElevations

public short[][] getElevations(EqualArc proj,
                               int dtedLevel)

Return the two-dimensional matrix of elevation posts (heights) representing coverage of a given geographical rectangle. The matrix represents coverage in an Equal Arc projection, and that's why the rectangle is defined by the projection parameters.

Parameters:

proj - the projection describing the wanted area

dtedLevel - the DTED level (0, 1, 2) to be used, which describes the geographicsal spacing between the posts.

Returns:

array of elevations, in meters. Spacing depends on the DTED level.

getElevations

public short[][] getElevations(float ullat,
                               float ullon,
                               float lrlat,
                               float lrlon,
                               int dtedLevel)

Return the two-dimensional matrix of elevation posts (heights) representing coverage of a given geographical rectangle. The matrix represents coverage in an Equal Arc projection. Doesn't handle projections which cross the dateline - You must handle that yourself by making two inquiries.

Parameters:

ullat - upper latitude, in decimal degrees

ullon - left longitude, in decimal degrees

lrlat - lower latitude, in decimal degrees

lrlon - right longitude, in decimal degrees

dtedLevel - the DTED level (0, 1, 2) to be used, which describes the geographicsal spacing between the posts.

getElevations

protected short[][] getElevations(float ullat,
                                  float ullon,
                                  float lrlat,
                                  float lrlon,
                                  int dtedLevel,
                                  DTEDSubframedFrame refFrame)

Return the two-dimensional matrix of elevation posts (heights) representing coverage of a given geographical rectangle. The matrix represents coverage in an Equal Arc projection. Doesn't handle projections which cross the dateline - You must handle that yourself by making two inquiries.

This method is slightly different that the one above, because it includes a input variable DTEDFrame. There is an inherent problem in the algorithm if some of the DTED frames are missing. It's too difficult to calculate the size of the return array if you don't know that any frames are available. So, you should always use the method above, which calls this method with a null refFrame. If some of the DTED frames are missing, then this method is called recursively, with a frame to use for calculating post spacings at the right time.

Parameters:

ullat - upper latitude, in decimal degrees

ullon - left longitude, in decimal degrees

lrlat - lower latitude, in decimal degrees

lrlon - right longitude, in decimal degrees

dtedLevel - the DTED level (0, 1, 2) to be used, which describes the geographicsal spacing between the posts.

refFrame - DTEDFrame used to calculate measurements.

Returns:

array of elevations, in meters. Spacing depends on the DTED level.

setPropertyPrefix

public void setPropertyPrefix(java.lang.String prefix)

PropertyConsumer method.

Specified by:

setPropertyPrefix in interface PropertyConsumer

Parameters:

prefix - the prefix String.

getPropertyPrefix

public java.lang.String getPropertyPrefix()

PropertyConsumer method.

Specified by:

getPropertyPrefix in interface PropertyConsumer

Returns:

the prefix string

setProperties

public void setProperties(java.util.Properties props)

PropertyConsumer method.

Specified by:

setProperties in interface PropertyConsumer

Parameters:

props - a properties object that the PropertyConsumer can use to retrieve expected properties it can use for configuration.

setProperties

public void setProperties(java.lang.String prefix,
                          java.util.Properties props)

PropertyConsumer method.

Specified by:

setProperties in interface PropertyConsumer

Parameters:

prefix - a String used by the PropertyConsumer to prepend to each property value it wants to look up - setList.getProperty(prefix.propertyKey). If the prefix had already been set, then the prefix passed in should replace that previous value.

props - a Properties object that the PropertyConsumer can use to retrieve expected properties it can use for configuration.

getProperties

public java.util.Properties getProperties(java.util.Properties props)

PropertyConsumer method.

Specified by:

getProperties in interface PropertyConsumer

Parameters:

props - a Properties object to load the PropertyConsumer properties into. If getList equals null, then a new Properties object should be created.

Returns:

Properties object containing PropertyConsumer property values. If getList was not null, this should equal getList. Otherwise, it should be the Properties object created by the PropertyConsumer.

getPropertyInfo

public java.util.Properties getPropertyInfo(java.util.Properties props)

PropertyConsumer method.

Specified by:

getPropertyInfo in interface PropertyConsumer

Parameters:

props - a Properties object to load the PropertyConsumer properties into. If getList equals null, then a new Properties object should be created.

Returns:

Properties object containing PropertyConsumer property values. If getList was not null, this should equal getList. Otherwise, it should be the Properties object created by the PropertyConsumer.

main

public static void main(java.lang.String[] args)