edu.d.umn.fileformats
Class DDFFileAbstract

java.lang.Object
  edu.d.umn.fileformats.ElevationFile
      edu.d.umn.fileformats.DDFFileAbstract

Direct Known Subclasses:

DDFFile, GZDDFFile

public abstract class DDFFileAbstract
extends ElevationFile

Provides basic methods to allow for tarballed DDF files or untarred DDF files.

Field Summary

protected java.lang.String	fileID
protected int	lengthOfFirstDirectoryElement
protected int	lengthOfLastDirectoryElement
protected int	lengthOfNextDirectoryElement
protected int	numDirectoryElements
protected int	startingPointOfDDA

Fields inherited from class edu.d.umn.fileformats.ElevationFile

elevations, fileName, filePath, groundCoordinates, maxElevation, minElevation, nColumns, nRows, quadrangleName, resolution

Constructor Summary

DDFFileAbstract()
Creates a new instance of DDFFileAbstract

Method Summary

protected int	processElevations(java.io.InputStream reader)
protected int	processGroundCoordinates(java.io.InputStream reader) Searches through the iden file of the ddf records to get the north and west latitude and longitude.
protected int	processLeader(java.io.InputStream reader) Parses the contents of a data record leader.
protected int	processMinMaxElevation(java.io.InputStream reader) Searches through the ddom file of the ddf records to get the minimum and maximum elevation.
protected int	processRowColMax(java.io.InputStream reader) Searches the ldef file to find the number of rows and columns to expect for the elevation data.

Methods inherited from class edu.d.umn.fileformats.ElevationFile

getResolution

Methods inherited from class java.lang.Object

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

Field Detail

numDirectoryElements

protected int numDirectoryElements

lengthOfFirstDirectoryElement

protected int lengthOfFirstDirectoryElement

lengthOfNextDirectoryElement

protected int lengthOfNextDirectoryElement

lengthOfLastDirectoryElement

protected int lengthOfLastDirectoryElement

startingPointOfDDA

protected int startingPointOfDDA

fileID

protected java.lang.String fileID

Constructor Detail

DDFFileAbstract

public DDFFileAbstract()

Creates a new instance of DDFFileAbstract

Method Detail

processLeader

protected int processLeader(java.io.InputStream reader)
                     throws java.io.IOException,
                            java.net.MalformedURLException

Parses the contents of a data record leader. This may or may not be the record leader for the file. Needed values are stored in the class variables, and the rest is discarded. This should position the reader at the first directory entry itself, which will usually be 0000;&ModuleName.

Parameters:

reader - The InputStream to work with.

Returns:

the number of bytes read.

Throws:

java.io.IOException

java.net.MalformedURLException

processGroundCoordinates

protected int processGroundCoordinates(java.io.InputStream reader)
                                throws java.io.IOException

Searches through the iden file of the ddf records to get the north and west latitude and longitude. Values are stored such that 46 degrees, 45 minutes and 0 seconds becomes 467,500.0 Since the USGS SDTS DEMs are 7.5 minute DEMs, the south and east coordinates are found by subtracting 1250 from the west and north coordinates

Returns:

The number of bytes read.

Throws:

java.io.IOException

processMinMaxElevation

protected int processMinMaxElevation(java.io.InputStream reader)
                              throws java.io.IOException

Searches through the ddom file of the ddf records to get the minimum and maximum elevation. Takes advantage of the fact that the values are immediately preceded by the keywords MIN or MAX, so we just look for those and then parse the set of integers that follows.

Returns:

The number of bytes read.

Throws:

java.io.IOException

processElevations

protected int processElevations(java.io.InputStream reader)
                         throws java.io.IOException

Throws:

java.io.IOException

processRowColMax

protected int processRowColMax(java.io.InputStream reader)
                        throws java.io.IOException

Searches the ldef file to find the number of rows and columns to expect for the elevation data. Assumes that the number of columns comes directly after the number of rows.

Returns:

The number of bytes read.

Throws:

java.io.IOException