ossimDtedRecord Class Reference

#include <ossimDtedRecord.h>

Inheritance diagram for ossimDtedRecord:

Public Types
enum	{   DATA_LENGTH = 12, DATA_BLOCK_COUNT = 2, DATA_LON_COUNT = 4, DATA_LAT_COUNT = 6,   DATA_ELEV_START = 8, DATA_BYTES_PER_POINT = 2 }

Public Member Functions
	ossimDtedRecord (std::istream &in, ossim_int32 offest, ossim_int32 num_points)
	~ossimDtedRecord ()
ossimString	recognitionSentinel () const
ossim_int32	dataBlockCount () const
ossim_int32	lonCount () const
ossim_int32	latCount () const
ossim_uint32	checkSum () const
ossim_uint32	computedCheckSum () const
ossim_int32	numPoints () const
ossim_int32	getPoint (ossim_int32 i) const
ossim_uint16	getPointData (ossim_int32 i) const
ossim_int32 *	points () const
ossim_uint16 *	pointsData () const
ossim_int32	startOffset () const
ossim_int32	stopOffset () const
void	parse (std::istream &in)
Public Member Functions inherited from ossimErrorStatusInterface
	ossimErrorStatusInterface ()
virtual	~ossimErrorStatusInterface ()
virtual ossimErrorCode	getErrorStatus () const
virtual ossimString	getErrorStatusString () const
virtual void	setErrorStatus (ossimErrorCode error_status) const
virtual void	setErrorStatus () const
virtual void	clearErrorStatus () const
bool	hasError () const
virtual std::ostream &	print (std::ostream &out) const
	Outputs theErrorStatus as an ossimErrorCode and an ossimString. More...

Private Member Functions
	ossimDtedRecord (const ossimDtedRecord &source)
bool	validateCheckSum (std::istream &in)

Private Attributes
ossim_int32	theFile
ossimString	theRecSen
ossim_int32	theDataBlockCount
ossim_int32	theLonCount
ossim_int32	theLatCount
ossim_uint32	theCheckSum
ossim_int32 *	thePoints
ossim_uint16 *	thePointsData
ossim_uint32	theComputedCheckSum
ossim_int32	theNumPoints
ossim_int32	theStartOffset
ossim_int32	theStopOffset

Friends
OSSIM_DLL std::ostream &	operator<< (std::ostream &os, const ossimDtedRecord &rec)

Additional Inherited Members
Protected Attributes inherited from ossimErrorStatusInterface
ossimErrorCode	theErrorStatus

Detailed Description

Definition at line 31 of file ossimDtedRecord.h.

Member Enumeration Documentation

anonymous enum

anonymous enum

Enumerator
DATA_LENGTH
DATA_BLOCK_COUNT
DATA_LON_COUNT
DATA_LAT_COUNT
DATA_ELEV_START
DATA_BYTES_PER_POINT

Definition at line 55 of file ossimDtedRecord.h.

   {
      DATA_LENGTH = 12,
      DATA_BLOCK_COUNT = 2,
      DATA_LON_COUNT = 4,
      DATA_LAT_COUNT = 6,
      DATA_ELEV_START = 8,
      DATA_BYTES_PER_POINT = 2,
   };

Constructor & Destructor Documentation

ossimDtedRecord() [1/2]

ossimDtedRecord::ossimDtedRecord	(	std::istream &	in,
		ossim_int32	offest,
		ossim_int32	num_points
	)

Definition at line 50 of file ossimDtedRecord.cpp.

   :
      theRecSen("170"),
      theDataBlockCount(0),
      theLonCount(0),
      theLatCount(0),
      theCheckSum(0),
      thePoints(new ossim_int32[num_points]),
      thePointsData(new ossim_uint16[num_points]),
      theComputedCheckSum(0),
      theNumPoints(num_points),
      theStartOffset(offset),
      theStopOffset(offset + RECORD_HDR_LENGTH + (num_points*BYTES_PER_POINT))
{
   // Verify we are at a cell record by checking the Recognition Sentinel.
   ossim_uint8 buf[1];
   in.seekg(theStartOffset, std::ios::beg);
   in.read((char*)buf, 1);
 
#if 0
   printf("\nBuf: %02X", (int)buf[0]);  // Display in HEX
#endif
   
   if(buf[0] != DATA_RECOGNITION_SENTINEL)
   {
      theErrorStatus = ossimErrorCodes::OSSIM_ERROR;
      ossimNotify(ossimNotifyLevel_FATAL) << "FATAL ossimDtedRecord::ossimDtedRecord: reading DTED's data record at: " << theStartOffset
                                          << std::endl;
      return;
   }

   // Valid data record, so let's process on.
   parse(in);

   //***
   // Note:  The validateCheckSum method works; however, our in-house
   //        dted has bad stored check sums even though the post are good.
   //        So this in temporarily shut off.
   //***
   // Verify Check Sum for uncorrupted elevation data.
   if(validateCheckSum(in) == false)
   {
      //***
      // Note:  The validateCheckSum method works; however, our in-house
      //        dted has bad stored check sums even though the posts are good.
      //        So this in temporarily shut off.
      //***
      theErrorStatus = ossimErrorCodes::OSSIM_ERROR;
      ossimNotify(ossimNotifyLevel_FATAL)
         << "FATAL ossimDtedRecord::ossimDtedRecord:"
         << "\nInvalid checksum in data record at: "
         << theStartOffset
         << "\nParsed Check Sum = " << theCheckSum
         << "\nComputed Check Sum = " << theComputedCheckSum
         << "\nDTED Elevation File is considered corrupted."
         << std::endl;
      return;
   }
}

~ossimDtedRecord()

ossimDtedRecord::~ossimDtedRecord

(

)

Definition at line 112 of file ossimDtedRecord.cpp.

References thePoints, and thePointsData.

{
   if (thePoints)
   {
      delete [] thePoints;
      thePoints = NULL;
   }
   if (thePointsData)
   {
      delete [] thePointsData;
      thePointsData = NULL;
   }
}

ossimDtedRecord() [2/2]

ossimDtedRecord::ossimDtedRecord ( const ossimDtedRecord &  source )

private

Member Function Documentation

checkSum()

ossim_uint32 ossimDtedRecord::checkSum

(

)

const

Definition at line 226 of file ossimDtedRecord.cpp.

References theCheckSum.

{
   return theCheckSum;
}

computedCheckSum()

ossim_uint32 ossimDtedRecord::computedCheckSum

(

)

const

Definition at line 231 of file ossimDtedRecord.cpp.

References theComputedCheckSum.

{
   return theComputedCheckSum;
}

dataBlockCount()

ossim_int32 ossimDtedRecord::dataBlockCount

(

)

const

Definition at line 211 of file ossimDtedRecord.cpp.

References theDataBlockCount.

{
   return theDataBlockCount;
}

getPoint()

ossim_int32 ossimDtedRecord::getPoint

(

ossim_int32

i

)

const

Definition at line 241 of file ossimDtedRecord.cpp.

References thePoints.

{
   return thePoints[i];
}

getPointData()

ossim_uint16 ossimDtedRecord::getPointData

(

ossim_int32

i

)

const

Definition at line 246 of file ossimDtedRecord.cpp.

References thePointsData.

{
   return thePointsData[i];
}

latCount()

ossim_int32 ossimDtedRecord::latCount

(

)

const

Definition at line 221 of file ossimDtedRecord.cpp.

References theLatCount.

{
   return theLatCount;
}

lonCount()

ossim_int32 ossimDtedRecord::lonCount

(

)

const

Definition at line 216 of file ossimDtedRecord.cpp.

References theLonCount.

{
   return theLonCount;
}

numPoints()

ossim_int32 ossimDtedRecord::numPoints

(

)

const

Definition at line 236 of file ossimDtedRecord.cpp.

References theNumPoints.

{
   return theNumPoints;
}

parse()

void ossimDtedRecord::parse

(

std::istream &

in

)

Definition at line 129 of file ossimDtedRecord.cpp.

References ossim::byteOrder(), OSSIM_LITTLE_ENDIAN, theStartOffset, and true.

{
   // DTED is stored in big endian byte order so swap the bytes if needed.
   bool swap_bytes = ossim::byteOrder() == OSSIM_LITTLE_ENDIAN ? true : false;
   
   ossim_sint16 s;
   
   // parse data block count
   in.seekg(theStartOffset + BLOCK_COUNT_OFFSET, std::ios::beg);
   in.read((char*)&s, 2);
   theDataBlockCount =
      (swap_bytes ? ( ( (s & 0x00ff) << 8) | ( (s & 0xff00) >> 8) ) : s);
   
   // parse lon count
   in.seekg(theStartOffset + LON_INDEX_OFFSET, std::ios::beg);
   in.read((char*)&s, 2);
   theLonCount =
      (swap_bytes ? ( ( (s & 0x00ff) << 8) | ( (s & 0xff00) >> 8) ) : s);
   
   // parse lat count
   in.seekg(theStartOffset + LAT_INDEX_OFFSET, std::ios::beg);
   in.read((char*)&s, 2);
   theLatCount =
      (swap_bytes ? ( ( (s & 0x00ff) << 8) | ( (s & 0xff00) >> 8) ) : s);
   
   // Parse all elevation points.
   in.seekg(theStartOffset + ELEV_DATA_OFFSET, std::ios::beg);
   for(int i = 0; i < theNumPoints; ++i)
   {
      in.read((char*)&s, 2);
      s = (swap_bytes ? ( ( (s & 0x00ff) << 8) | ( (s & 0xff00) >> 8) ) : s);
      if (s & DATA_SIGN_MASK)
      {
         s = (s & DATA_VALUE_MASK) * -1;
      }
      thePoints[i] = static_cast<ossim_int32>(s);
      thePointsData[i] = s;
   }
}

points()

ossim_int32 * ossimDtedRecord::points

(

)

const

Definition at line 251 of file ossimDtedRecord.cpp.

References thePoints.

{
   return thePoints;
}

pointsData()

ossim_uint16 * ossimDtedRecord::pointsData

(

)

const

Definition at line 256 of file ossimDtedRecord.cpp.

References thePointsData.

{
   return thePointsData;
}

recognitionSentinel()

ossimString ossimDtedRecord::recognitionSentinel

(

)

const

Definition at line 206 of file ossimDtedRecord.cpp.

References theRecSen.

{
   return theRecSen;
}

startOffset()

ossim_int32 ossimDtedRecord::startOffset

(

)

const

Definition at line 261 of file ossimDtedRecord.cpp.

References theStartOffset.

{
   return theStartOffset;
}

stopOffset()

ossim_int32 ossimDtedRecord::stopOffset

(

)

const

Definition at line 266 of file ossimDtedRecord.cpp.

References theStopOffset.

{
   return theStopOffset;
}

validateCheckSum()

bool ossimDtedRecord::validateCheckSum ( std::istream &  in )

private

Compute the check sum for the Data Record and compare against the parsed check sum from the data record. This must be correct to be a valid data record. If not, there is a chance of a corrupted elevation cell.

Returns

true if check sum validates, false if not.

Definition at line 172 of file ossimDtedRecord.cpp.

References ossim::byteOrder(), OSSIM_LITTLE_ENDIAN, theComputedCheckSum, theNumPoints, theStartOffset, and true.

{
   // DTED is stored in big endian byte order so swap the bytes if needed.
   bool swap_bytes = ossim::byteOrder() == OSSIM_LITTLE_ENDIAN ? true : false;
   
   // Compute the check sum.
   in.seekg(theStartOffset, std::ios::beg);
   theComputedCheckSum = 0;
   ossim_int32 bytesToRead = (theNumPoints * 2) + ELEV_DATA_OFFSET;
   int i = 0;
   
   for(i = 0; i < bytesToRead; i++)
   {
      ossim_uint8 c;
      in.read((char*)&c, 1);
      theComputedCheckSum += static_cast<ossim_uint32>(c);
   }   

   // Read the stored check sum and swap the byte if needed.
   in.read((char*)&theCheckSum, 4); 
   if (swap_bytes)
   {
      ossimEndian swapper;
      swapper.swap(theCheckSum);
   }
   
   // Compare computed and parsed checksums.
   if(theCheckSum != theComputedCheckSum)
   {
      return false;
   }
   return true;
}

Friends And Related Function Documentation

operator<<

OSSIM_DLL std::ostream& operator<< ( std::ostream &  os, const ossimDtedRecord &  rec  )

friend

Definition at line 274 of file ossimDtedRecord.cpp.

{
   os << "\nDTED Record:"
      << "\n-------------------------------"
      << "\n Recognition Sentinel: " << rec.theRecSen
      << "\nData Block Count:      " << rec.theDataBlockCount
      << "\nLon Count:             " << rec.theLonCount
      << "\nLat Count:             " << rec.theLatCount
      << "\nNum Points:            " << rec.theNumPoints
      << "\nParsed Check Sum:      " << rec.theCheckSum
      << "\nComputed Check Sum     " << rec.theComputedCheckSum
      << "\nStart Offset:          " << rec.theStartOffset
      << "\nStop Offset:           " << rec.theStopOffset
      << std::endl;
   int i = 0;

   for(i = 0; i < rec.theNumPoints; i++)
   {
      os << "\nPoint[" << i << "]: " << rec.thePoints[i];
   }

   os << std::endl;

   return os;
}

Member Data Documentation

theCheckSum

ossim_uint32 ossimDtedRecord::theCheckSum

private

Algebraic addition of contents of block. The checksum is computed algebraically using integer arithmetic by summing all header and elevation bytes contained int the record as 8-bit values. Each byte is considered an unsigned, 8-bit value for checksum calculation.

Definition at line 125 of file ossimDtedRecord.h.

Referenced by checkSum(), and operator<<().

theComputedCheckSum

ossim_uint32 ossimDtedRecord::theComputedCheckSum

private

Our computed check sum. This should match the checksum at the end of the Data Record.

Definition at line 143 of file ossimDtedRecord.h.

Referenced by computedCheckSum(), operator<<(), and validateCheckSum().

theDataBlockCount

ossim_int32 ossimDtedRecord::theDataBlockCount

private

Sequential count of the block within the file.

Definition at line 102 of file ossimDtedRecord.h.

Referenced by dataBlockCount(), and operator<<().

theFile

ossim_int32 ossimDtedRecord::theFile

private

Definition at line 92 of file ossimDtedRecord.h.

theLatCount

ossim_int32 ossimDtedRecord::theLatCount

private

Count of the parallel. True latitude = latitude count x data interval + origin (Offset from the SW corner latitude)

Definition at line 116 of file ossimDtedRecord.h.

Referenced by latCount(), and operator<<().

theLonCount

ossim_int32 ossimDtedRecord::theLonCount

private

Count of the meridian. True longitude = longitude count x data interval + origin (Offset from the SW corner longitude)

Definition at line 109 of file ossimDtedRecord.h.

Referenced by lonCount(), and operator<<().

theNumPoints

ossim_int32 ossimDtedRecord::theNumPoints

private

The number of points in a longitudinal line.

Definition at line 148 of file ossimDtedRecord.h.

Referenced by numPoints(), operator<<(), and validateCheckSum().

thePoints

ossim_int32* ossimDtedRecord::thePoints

private

All the elevation points in a Data Record as ints. (ie. all the latitudal points in a longitudinal line)

Definition at line 131 of file ossimDtedRecord.h.

Referenced by getPoint(), operator<<(), points(), and ~ossimDtedRecord().

thePointsData

ossim_uint16* ossimDtedRecord::thePointsData

private

All the elevation points in a Data Record as unsigned shorts. (ie. all the latitudal points in a longitudinal line)

Definition at line 137 of file ossimDtedRecord.h.

Referenced by getPointData(), pointsData(), and ~ossimDtedRecord().

theRecSen

ossimString ossimDtedRecord::theRecSen

private

252 (8 bit)

Definition at line 97 of file ossimDtedRecord.h.

Referenced by operator<<(), and recognitionSentinel().

theStartOffset

ossim_int32 ossimDtedRecord::theStartOffset

private

Definition at line 150 of file ossimDtedRecord.h.

Referenced by operator<<(), parse(), startOffset(), and validateCheckSum().

theStopOffset

ossim_int32 ossimDtedRecord::theStopOffset

private

Definition at line 151 of file ossimDtedRecord.h.

Referenced by operator<<(), and stopOffset().

---

The documentation for this class was generated from the following files:

• ossimDtedRecord.h
• ossimDtedRecord.cpp