ossimDemGrid Class Reference

#include <ossimDemGrid.h>

Public Member Functions
	ossimDemGrid (ossim_float32 missingDataValue=-32768.0)
	~ossimDemGrid ()
long	read (ossim::istream &dem, bool incrementalRead=false)
ossimDemHeader const &	getHeader () const
long	getWidth () const
long	getHeight () const
ossim_float32	getElevation (long x, long y) const
ossim_float32	getMissingDataValue () const
void	getGroundCoords (long x, long y, double &ground_x, double &ground_y)

Private Member Functions
void	setElevation (long x, long y, ossim_float32 val)
long	fillGeographic (ossim::istream &dem, bool incrementalRead)
long	fillUTM (ossim::istream &dem, bool incrementalRead)

Private Attributes
ossim_float32	_missDataVal
ossimDemHeader	_header
long	_width
long	_height
ossim_float32 *	_grid
bool	_firstTime
long	_curProfile
std::vector< ossimDemProfile >	_profiles
double	_northwest_x
double	_northwest_y

Detailed Description

class ossimDemGrid This class uses the DEM library to read a DEM and construct a rectangular grid of signed 16 bit point values.

Definition at line 27 of file ossimDemGrid.h.

Constructor & Destructor Documentation

ossimDemGrid()

ossimDemGrid::ossimDemGrid

(

ossim_float32

missingDataValue = -32768.0

)

Missing or void data is replaced with missingDataValue.

Definition at line 20 of file ossimDemGrid.cpp.

   : _missDataVal(missingDataValue),
     _width(0),
     _height(0),
     _grid(0),
     _firstTime(true),
     _curProfile(0)
{        
}

~ossimDemGrid()

ossimDemGrid::~ossimDemGrid

(

)

Definition at line 30 of file ossimDemGrid.cpp.

References _grid.

{
   if(_grid)
   {
      delete [] _grid;
      _grid =0;
   }
}

Member Function Documentation

fillGeographic()

long ossimDemGrid::fillGeographic ( ossim::istream &  dem, bool  incrementalRead  )

private

Definition at line 94 of file ossimDemGrid.cpp.

References _curProfile, _firstTime, _grid, _header, _height, _northwest_x, _northwest_y, _profiles, _width, ossimDemHeader::getProfileColumns(), ossimDemHeader::getSpatialResY(), ossimDemPoint::getX(), ossimDemPoint::getY(), and setElevation().

Referenced by read().

{
   if (_firstTime) {
      _curProfile = 0;
      _width = _header.getProfileColumns();
   }

   while (_curProfile < _width)
   {
      _profiles.push_back(ossimDemProfile());
      dem >> _profiles.back();
      _curProfile++;
      if (incrementalRead)
         return _width - _curProfile + 1;
   }

   // Assume all profiles have as many elevations as the first.
   _height = _profiles[0].getNumberOfElevations();
   if(_grid)
   {
      delete [] _grid;
      _grid =0;
   }
   _grid = new ossim_float32[_width * _height];

   ossimDemPoint sw_corner = _profiles[0].getProfileLocation();
   _northwest_x = sw_corner.getX();
   _northwest_y = sw_corner.getY() 
                  + ((_profiles[0].getNumberOfElevations() - 1) * _header.getSpatialResY());


   unsigned int i,j;
   for (i = 0; (int)i < _width; i++)
   {
      ossimDemElevationVector const& elev = _profiles[i].getElevations();
      for (j = 0; j < elev.size(); j++)
      {
         setElevation(i, _height - j - 1, elev[j]);
      }
   }

   _profiles.erase(_profiles.begin(), _profiles.end());

   return 0;
}

fillUTM()

long ossimDemGrid::fillUTM ( ossim::istream &  dem, bool  incrementalRead  )

private

Definition at line 141 of file ossimDemGrid.cpp.

References _curProfile, _firstTime, _grid, _header, _height, _missDataVal, _northwest_x, _northwest_y, _profiles, _width, ossimDemHeader::getProfileColumns(), ossimDemHeader::getSpatialResY(), ossimDemPoint::getX(), ossimDemPoint::getY(), ossimNotify(), ossimNotifyLevel_FATAL, setElevation(), x, and y.

Referenced by read().

{
   // 7.5 UTM DEMs are small enough we can get away with doing this stupid...

   unsigned int i;
   unsigned int x,y;

   if (_firstTime)
   {
      _curProfile = 0;
      _width = _header.getProfileColumns();
   }


   while (_curProfile < _width)
   {
      _profiles.push_back(ossimDemProfile());
      dem >> _profiles.back();
      _curProfile++;
      if (incrementalRead)
         return _width - _curProfile + 1;
   }

   double dy = _header.getSpatialResY();

   // Determine min and max Y values.
   // Some DEMs can have profiles which do not have any
   // elevations, and erroneous (x,y) values. I suspect
   // these are probably illegal DEMs, but we'll try to
   // do the right thing anyway.
   ossimDemPoint curpoint;
   i = 0;
   while ((_profiles[i].getNumberOfElevations() == 0) &&
          (i < _profiles.size()))
      i++;
   if (i < _profiles.size())
      curpoint = _profiles[i].getProfileLocation();
   else
   {
      // XXX This isn't the best way to handle this...
      ossimNotify(ossimNotifyLevel_FATAL) << "FATAL ossimDemGrid::fillUTM: Yikes! All profiles have zero elevations!\n";
      return(1);
   }
 
   double miny, maxy;
   miny = curpoint.getY();
   maxy = miny;
   double profymin, profymax;  // Min and max y values for current profile.
   for (i = 0; i < _profiles.size(); i++)
   {
      if (_profiles[i].getNumberOfElevations() > 0)
      {
         curpoint = _profiles[i].getProfileLocation();
         profymin = curpoint.getY();
         profymax = profymin + ((_profiles[i].getNumberOfElevations() - 1) * dy);

         if (profymin < miny)
            miny = profymin;
         if (profymax > maxy)
            maxy = profymax;
      }
   }

   // We now have minimum and maximum y values over all profiles in the DEM.
   // Allocate a rectangular array large enough to hold them.

   _height = static_cast<long>(((maxy - miny) / dy) + 1);
   if(_grid)
   {
      delete [] _grid;
      _grid =0;
   }
   _grid = new ossim_float32[_width * _height];

   // Fill grid with the "missing data" value.
   for (i = 0; (int)i < _width * _height; i++)
      _grid[i] = _missDataVal;

   ossimDemPoint sw_corner = _profiles[0].getProfileLocation();
   _northwest_x = sw_corner.getX();
   _northwest_y = maxy;


   // Now, insert the elevations in the profiles in the appropriate place in the grid.

   long startpos;
   for (x = 0; (int)x < _width; x++)
   {
      ossimDemElevationVector const& elev = _profiles[x].getElevations();
      curpoint = _profiles[x].getProfileLocation();
      startpos = static_cast<long>((curpoint.getY() - miny) / dy);
      for (y = 0; y < elev.size(); y++)
      {
         setElevation(x, _height - startpos - y - 1, elev[y]);
      }
   }

   _profiles.erase(_profiles.begin(), _profiles.end());

   return 0;
}

getElevation()

ossim_float32 ossimDemGrid::getElevation	(	long	x,
		long	y
	)		const

Returns the elevation value at (x,y). (0,0) is in the upper left corner, x is positive to the right, y is positive down.

Definition at line 78 of file ossimDemGrid.cpp.

References _grid, _height, _missDataVal, _width, x, and y.

Referenced by ossimUsgsDemTileSource::fillBuffer().

{
   if (_grid == 0)
      return _missDataVal;

   if ((x < 0) || (y < 0) || (x >= _width) || (y >= _height))
      return _missDataVal;

   return _grid[(y * _width) + x];
}

getGroundCoords()

void ossimDemGrid::getGroundCoords	(	long	x,
		long	y,
		double &	ground_x,
		double &	ground_y
	)

(x,y) are the coordinates of a elevation value in the dem. (ground_x, ground_y) are the coordinates of that value in the units of the horizontal projection system used by the dem.

Definition at line 244 of file ossimDemGrid.cpp.

References _header, _northwest_x, _northwest_y, ossimDemHeader::getSpatialResX(), ossimDemHeader::getSpatialResY(), x, and y.

{
   ground_x = _northwest_x + (x * _header.getSpatialResX());
   ground_y = _northwest_y - (y * _header.getSpatialResY());
}

getHeader()

ossimDemHeader const & ossimDemGrid::getHeader

(

)

const

Definition at line 61 of file ossimDemGrid.cpp.

References _header.

Referenced by ossimUsgsDemTileSource::fillBuffer(), and ossimUsgsDemTileSource::getInternalImageGeometry().

{
   return _header;
}

getHeight()

long ossimDemGrid::getHeight

(

)

const

Returns the number of rows in the grid.

Definition at line 73 of file ossimDemGrid.cpp.

References _height.

Referenced by ossimUsgsDemTileSource::getNumberOfLines().

{
   return _height;
}

getMissingDataValue()

ossim_float32 ossimDemGrid::getMissingDataValue

(

)

const

Returns the value used to indicate missing data.

Definition at line 89 of file ossimDemGrid.cpp.

References _missDataVal.

{
   return _missDataVal;
}

getWidth()

long ossimDemGrid::getWidth

(

)

const

Returns the number of columns in the grid.

Definition at line 67 of file ossimDemGrid.cpp.

References _width.

Referenced by ossimUsgsDemTileSource::getNumberOfSamples().

{
   return _width;
}

read()

long ossimDemGrid::read	(	ossim::istream &	dem,
		bool	incrementalRead = false
	)

Convertes a DEM to a rectangular grid.

If incrementalRead is false, the entire DEM will be converted with just one call to read. 0 (zero) is returned if successful, -1 if error.

If incrementalRead is true, multiple calls to read are required, and the return value is as follows: >0 – Number of calls remaining until conversion is complete. ==0 – Conversion was successful. No more calls to read required. -1 – Error during conversion.

Definition at line 40 of file ossimDemGrid.cpp.

References _firstTime, _header, fillGeographic(), fillUTM(), and ossimDemHeader::getGroundRefSysCode().

{
   if (_firstTime)
   {
      dem >> _header;
   }

   long retval;
   if (_header.getGroundRefSysCode() == 0)  // Geographic
      retval = fillGeographic(dem,incrementalRead);
   else
      retval = fillUTM(dem,incrementalRead);   // This may not work if it's 
                                               // really in State Plane.

   if (_firstTime)
      _firstTime = false;

   return retval;
}

setElevation()

void ossimDemGrid::setElevation ( long  x, long  y, ossim_float32  val  )

inlineprivate

Definition at line 101 of file ossimDemGrid.h.

References _grid, _width, x, and y.

Referenced by fillGeographic(), and fillUTM().

{
   if (_grid == 0)
      return;

   _grid[(_width * y) + x] = val;
}

Member Data Documentation

_curProfile

long ossimDemGrid::_curProfile

private

Definition at line 92 of file ossimDemGrid.h.

Referenced by fillGeographic(), and fillUTM().

_firstTime

bool ossimDemGrid::_firstTime

private

Definition at line 91 of file ossimDemGrid.h.

Referenced by fillGeographic(), fillUTM(), and read().

_grid

ossim_float32* ossimDemGrid::_grid

private

Definition at line 90 of file ossimDemGrid.h.

Referenced by fillGeographic(), fillUTM(), getElevation(), setElevation(), and ~ossimDemGrid().

_header

ossimDemHeader ossimDemGrid::_header

private

Definition at line 87 of file ossimDemGrid.h.

Referenced by fillGeographic(), fillUTM(), getGroundCoords(), getHeader(), and read().

_height

long ossimDemGrid::_height

private

Definition at line 89 of file ossimDemGrid.h.

Referenced by fillGeographic(), fillUTM(), getElevation(), and getHeight().

_missDataVal

ossim_float32 ossimDemGrid::_missDataVal

private

Definition at line 86 of file ossimDemGrid.h.

Referenced by fillUTM(), getElevation(), and getMissingDataValue().

_northwest_x

double ossimDemGrid::_northwest_x

private

Definition at line 94 of file ossimDemGrid.h.

Referenced by fillGeographic(), fillUTM(), and getGroundCoords().

_northwest_y

double ossimDemGrid::_northwest_y

private

Definition at line 94 of file ossimDemGrid.h.

Referenced by fillGeographic(), fillUTM(), and getGroundCoords().

_profiles

std::vector<ossimDemProfile> ossimDemGrid::_profiles

private

Definition at line 93 of file ossimDemGrid.h.

Referenced by fillGeographic(), and fillUTM().

_width

long ossimDemGrid::_width

private

Definition at line 88 of file ossimDemGrid.h.

Referenced by fillGeographic(), fillUTM(), getElevation(), getWidth(), and setElevation().

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

• ossimDemGrid.h
• ossimDemGrid.cpp