Inheritance diagram for vtElevationGrid:

Public Member Functions
	vtElevationGrid ()

	vtElevationGrid (const vtElevationGrid &rhs)

	vtElevationGrid (const DRECT &area, const IPoint2 &size, bool bFloat, const vtCRS &proj)

virtual	~vtElevationGrid ()

vtElevationGrid &	operator= (const vtElevationGrid &rhs)

bool	CopyFrom (const vtElevationGrid &rhs)

bool	CopyHeaderFrom (const vtElevationGrid &rhs)

bool	CopyDataFrom (const vtElevationGrid &rhs)

bool	Create (const DRECT &area, const IPoint2 &size, bool bFloat, const vtCRS &proj, vtElevError *err=NULL)

void	FreeData ()

void	Clear ()

void	Invalidate ()

bool	ConvertProjection (vtElevationGrid pOld, const vtCRS &NewProj, float bUpgradeToFloat, bool progress_callback(int)=NULL, vtElevError err=NULL)

bool	ReprojectExtents (const vtCRS &proj_new)

void	Scale (float fScale, bool bDirect, bool bRecomputeExtents=true)

void	VertOffset (float fAmount)

void	ComputeHeightExtents ()

void	Offset (const DPoint2 &delta)

int	ReplaceValue (float value1, float value2)

bool	FillGaps (DRECT *area=NULL, bool progress_callback(int)=NULL)

bool	FillGapsSmooth (DRECT *area=NULL, bool progress_callback(int)=NULL)

int	FillGapsByRegionGrowing (int radius_start=2, int radius_stop=5, bool progress_callback(int)=NULL)

int	FillGapsByRegionGrowing (int radius, bool progress_callback(int)=NULL)

bool	LoadFromFile (const char szFileName, bool progress_callback(int)=NULL, vtElevError err=NULL)

bool	LoadFrom3TX (const char *szFileName, bool progress_callback(int)=NULL)

bool	LoadFromASC (const char *szFileName, bool progress_callback(int)=NULL)

bool	LoadFromDEM (const char szFileName, bool progress_callback(int)=NULL, vtElevError err=NULL)

bool	LoadFromTerragen (const char *szFileName, bool progress_callback(int)=NULL)

bool	LoadFromDTED (const char *szFileName, bool progress_callback(int)=NULL)

bool	LoadFromGTOPO30 (const char *szFileName, bool progress_callback(int)=NULL)

bool	LoadFromGLOBE (const char *szFileName, bool progress_callback(int)=NULL)

bool	LoadFromGRD (const char *szFileName, bool progress_callback(int)=NULL)

bool	LoadFromDSAA (const char *szFileName, bool progress_callback(int)=NULL)

bool	LoadFromPGM (const char *szFileName, bool progress_callback(int)=NULL)

bool	LoadFromRAW (const char *szFileName, int width, int height, int bytes_per_element, float vertical_units, bool bBigEndian, bool progress_callback(int))

bool	LoadFromMicroDEM (const char *szFileName, bool progress_callback(int)=NULL)

bool	LoadFromXYZ (const char *szFileName, bool progress_callback(int)=NULL)

bool	LoadFromXYZ (FILE fp, const char format, bool progress_callback(int)=NULL)

bool	LoadFromHGT (const char *szFileName, bool progress_callback(int)=NULL)

bool	LoadFromBT (const char szFileName, bool progress_callback(int)=NULL, vtElevError err=NULL)

bool	LoadBTHeader (const char szFileName, vtElevError err=NULL)

bool	LoadBTData (const char szFileName, bool progress_callback(int)=NULL, vtElevError err=NULL)

bool	LoadWithGDAL (const char szFileName, bool progress_callback(int)=NULL, vtElevError err=NULL)

bool	LoadFromNTF5 (const char *szFileName, bool progress_callback(int)=NULL)

bool	SaveTo3TX (const char *szFileName, bool progress_callback(int)=NULL) const

bool	SaveToGeoTIFF (const char *szFileName) const

bool	SaveToTerragen (const char *szFileName) const

bool	SaveToBT (const char *szFileName, bool progress_callback(int)=NULL, bool bGZip=false)

bool	SaveToSTM (const char *szFileName, bool progress_callback(int)=NULL)

bool	SaveToPlanet (const char *szDirName, bool progress_callback(int)=NULL)

bool	SaveToASC (const char *szFileName, bool progress_callback(int)=NULL) const

bool	SaveToVRML (const char *szFileName, bool progress_callback(int)=NULL) const

bool	SaveToXYZ (const char *szFileName, bool progress_callback(int)=NULL) const

bool	SaveToRAWINF (const char *szFileName, bool progress_callback(int)=NULL) const

bool	SaveToRAW_Unity (const char *szFileName, bool progress_callback(int)=NULL) const

bool	SaveToPNG16 (const char *fname)

void	SetFValue (int i, int j, float value)

void	SetValue (int i, int j, short value)

short	GetShortValue (int i, int j) const

float	GetFValue (int i, int j) const

float	GetFValueSafe (int i, int j) const

float	GetClosestValue (const DPoint2 &p) const

float	GetFilteredValue (const DPoint2 &p) const

const char *	GetDEMName ()

DRECT	GetAreaExtents () const

bool	IsFloatMode () const

void	FillWithSingleValue (float fValue)

void	GetEarthPoint (int i, int j, DPoint2 &p) const

void	GetEarthLocation (int i, int j, DPoint3 &loc) const

vtCRS &	GetCRS ()

const vtCRS &	GetProjection () const

void	SetProjection (const vtCRS &proj)

bool	GetCorners (DLine2 &line, bool bGeo) const

void	SetCorners (const DLine2 &line)

short *	GetData ()

float *	GetFloatData ()

const short *	GetData () const

const float *	GetFloatData () const

void	SetScale (float sc)

float	GetScale () const

bool	HasData () const

int	MemoryNeededToLoad () const

int	MemoryUsed () const

bool	FindAltitudeOnEarth (const DPoint2 &p, float &fAltitude, bool bTrue=false) const

virtual float	GetElevation (int iX, int iZ, bool bTrue=false) const

virtual void	GetWorldLocation (int i, int j, FPoint3 &loc, bool bTrue=false) const

void	SetupLocalCS (float fVerticalExag=1.0f)

float	GetWorldValue (int i, int j, bool bTrue=false) const

bool	FindAltitudeAtPoint (const FPoint3 &p3, float &fAltitude, bool bTrue=false, int iCultureFlags=0, FPoint3 *vNormal=NULL) const

Public Member Functions inherited from vtHeightFieldGrid3d
void	Initialize (const LinearUnits units, const DRECT &earthextents, float fMinHeight, float fMaxHeight, int cols, int rows)

virtual void	SetEarthExtents (const DRECT &ext)

bool	CastRayToSurface (const FPoint3 &point, const FPoint3 &dir, FPoint3 &result) const

bool	LineOfSight (const FPoint3 &point1, const FPoint3 &point2) const

const DPoint2 &	GetSpacing () const

const FPoint2 &	GetWorldSpacing () const

void	GetDimensions (int &nColumns, int &nRows) const

const IPoint2 &	GetDimensions () const

int	NumColumns () const

int	NumRows () const

void	EarthToGrid (const DPoint2 &epos, IPoint2 &ipos)

void	WorldToGrid (const FPoint3 &pos, IPoint2 &ipos)

float	GetInterpolatedElevation (double findex_x, double findex_y, bool bTrue=false) const

int	FindNumUnknown ()

bool	ColorDibFromElevation (vtBitmapBase pBM, ColorMap cmap, int iGranularity, const RGBAi &nodata, bool progress_callback(int)=NULL) const

bool	ColorDibFromTable (vtBitmapBase pBM, const ColorMap color_map, const RGBAi &nodata, bool progress_callback(int)=NULL) const

void	ShadeDibFromElevation (vtBitmapBase *pBM, const FPoint3 &light_dir, float fLightFactor, float fAmbient=0.1f, float fGamma=1.0f, bool bTrue=false, bool progress_callback(int)=NULL) const

void	ShadeQuick (vtBitmapBase *pBM, float light_factor, bool bTrue=false, bool progress_callback(int)=NULL)

void	ShadowCastDib (vtBitmapBase *pBM, const FPoint3 &ight_dir, float fLightFactor, float fAmbient, bool progress_callback(int)=NULL) const

Public Member Functions inherited from vtHeightField3d
void	Initialize (const LinearUnits units, const DRECT &earthextents, float fMinHeight, float fMaxHeight)

int	PointIsAboveTerrain (const FPoint3 &p) const

bool	ConvertEarthToSurfacePoint (const DPoint2 &epos, FPoint3 &p3, int iCultureFlags=0, bool bTrue=false) const

bool	ContainsWorldPoint (float x, float z) const

void	GetCenter (FPoint3 &center) const

void	SetCulture (CultureExtension *ext)

float	LineOnSurface (const DLine2 &line, float fSpacing, float fOffset, bool bInterp, bool bCurve, bool bTrue, FLine3 &output)

Public Member Functions inherited from vtHeightField
void	Initialize (const DRECT &extents, float fMinHeight, float fMaxHeight)

bool	ContainsEarthPoint (const DPoint2 &p, bool bInclusive=false) const

DRECT &	GetEarthExtents ()

const DRECT &	GetEarthExtents () const

void	GetHeightExtents (float &fMinHeight, float &fMaxHeight) const

Protected Member Functions
void	SetupMembers ()

void	ComputeExtentsFromCorners ()

void	ComputeCornersFromExtents ()

bool	ParseNTF5 (GDALDataset *pDatasource, vtString &msg, bool progress_callback(int))

bool	GetXYZLine (const char buf, const char pattern, const char format, int components, double x, double y, double z)

void	SetError (vtElevError err, vtElevError::ErrorType type, const char szFormat,...)

bool	AllocateGrid (vtElevError *err=NULL)

Protected Member Functions inherited from vtHeightField3d
void	UpdateWorldExtents ()

Protected Attributes
bool	m_bFloatMode

short *	m_pData

float *	m_pFData

float	m_fVMeters

float	m_fVerticalScale

DPoint2	m_Corners [4]

vtCRS	m_proj

vtString	m_strOriginalDEMName

Protected Attributes inherited from vtHeightFieldGrid3d
IPoint2	m_iSize

FPoint2	m_fStep

DPoint2	m_dStep

Protected Attributes inherited from vtHeightField3d
float	m_fDiagonalLength

CultureExtension *	m_pCulture

Protected Attributes inherited from vtHeightField
float	m_fMinHeight

float	m_fMaxHeight

DRECT	m_EarthExtents

Additional Inherited Members
Public Attributes inherited from vtHeightField3d
FRECT	m_WorldExtents

LocalCS	m_LocalCS

Detailed Description

The vtElevationGrid class represents a generic grid of elevation data. It supports reading and writing the data from many file formats, testing the height at any given point, reprojecting the grid between coordinate systems, and many other operations.

Height elements ("heixels") can be either integer (2 bytes) or floating point (4 bytes). Heixel values are always in meters. Areas of unknown elevation are represented by the value INVALID_ELEVATION.

To load a grid from a file, first create an empty grid, then call the appropriated Load method.

Constructor & Destructor Documentation

vtElevationGrid::vtElevationGrid ( )

Constructor: Creates an empty grid.

vtElevationGrid::vtElevationGrid ( const vtElevationGrid & rhs )

Copy constructor.

vtElevationGrid::vtElevationGrid	(	const DRECT &	area,
		const IPoint2 &	size,
		bool	bFloat,
		const vtCRS &	proj
	)

Constructor: Creates a grid of given size.

Parameters

area	the coordinate extents of the grid (rectangular area)
size	Number of columns and rows in the grid
bFloat	data size: `true` to use floating-point, `false` for shorts.
proj	the geographical projection to use.

The grid will initially have no data in it (all values are INVALID_ELEVATION).

vtElevationGrid::~vtElevationGrid ( )

virtual

Destructor

Member Function Documentation

void vtElevationGrid::Clear ( )

Set all the values in the grid to zero.

void vtElevationGrid::ComputeCornersFromExtents ( )

protected

For a grid whose absolute extents are known, use those extents to imply the 4 corners coordinates.

void vtElevationGrid::ComputeExtentsFromCorners ( )

protected

For a grid whose 4 corners coordinates are known, use those corners to imply absolute extents.

void vtElevationGrid::ComputeHeightExtents ( )

Scans the grid to compute the minimum and maximum height values.

See also: GetHeightExtents

bool vtElevationGrid::ConvertProjection	(	vtElevationGrid *	pOld,
		const vtCRS &	NewProj,
		float	bUpgradeToFloat,
		bool	progress_callbackint = `NULL`,
		vtElevError *	err = `NULL`
	)

Initializes an elevation grid by converting the contents of an another grid to a new projection.

Parameters

pOld	An existing elevation grid to convert from.
NewProj	The new projection to convert to.
bUpgradeToFloat	If true, the resulting grid will always use floating-point values. Otherwise, it matches the input grid.
progress_callback	If supplied, this function will be called back with a value of 0 to 100 as the operation progresses.
err	If supplied, will be set to a description of any error that occurs.

Returns: True if successful.

bool vtElevationGrid::Create	(	const DRECT &	area,
		const IPoint2 &	size,
		bool	bFloat,
		const vtCRS &	proj,
		vtElevError *	err = `NULL`
	)

Create a grid of given size.

Parameters

area	the coordinate extents of the grid (rectangular area)
size	Number of columns and rows in the grid.
bFloat	data size: `true` to use floating-point, `false` for shorts.
proj	the geographical projection to use.
err	If supplied, will be set to a description of any error that occurs.

The grid will initially have no data in it (all values are INVALID_ELEVATION).

bool vtElevationGrid::FillGaps	(	DRECT *	area = `NULL`,
		bool	progress_callbackint = `NULL`
	)

Fill the gaps (heixels of value INVALID_ELVATION) in this grid, by interpolating from the valid values.

This method uses a simple, unoptimized algorithm to move across the grid, one column at a time, averaging the surrounding pixels to fill each gap.

Parameters

area	Optionally, restrict the operation to a given area.
progress_callback	Provide if you want a callback on progress.

Returns: true if successful, false if cancelled.

int vtElevationGrid::FillGapsByRegionGrowing	(	int	radius_start = `2`,
		int	radius_stop = `5`,
		bool	progress_callbackint = `NULL`
	)

Fill-in algorithm. Replaces no-data values by repeated region growing. Smoothly extrapolates the filled-in value via partial derivatives. Restricts the fill-in operation to concavities with a diameter of less than radius^2+1 pixels.

Returns: The number of no-data heixels that were filled. Returns -1 on error, for example if there was not enought memory to create the temporary buffers.

int vtElevationGrid::FillGapsByRegionGrowing	(	int	radius,
		bool	progress_callbackint = `NULL`
	)

Fill-in algorithm. Replaces no-data values by repeated region growing. Smoothly extrapolates the filled-in value via partial derivatives. Restricts the fill-in operation to concavities with a diameter of less than radius^2+1 pixels.

Adapted subset from original code by: Stefan Roettger.

Returns: The number of no-data heixels that were filled. Returns -1 on error, for example if there was not enought memory to create the temporary buffers.

bool vtElevationGrid::FillGapsSmooth	(	DRECT *	area = `NULL`,
		bool	progress_callbackint = `NULL`
	)

Fill the gaps (heixels of value INVALID_ELVATION) in this grid, by interpolating from the valid values.

This method attempts to be a little better than FillGaps(), by keeping an entire second grid for the interpolated results on each pass, to avoid some cases of the results getting "smeared" left to right. However, this makes it much slower on most data.

Parameters

area	Optionally, restrict the operation to a given area.
progress_callback	Provide if you want a callback on progress.

Returns: true if successful, false if cancelled.

bool vtElevationGrid::FindAltitudeAtPoint	(	const FPoint3 &	p,
		float &	fAltitude,
		bool	bTrue = `false`,
		int	iCultureFlags = `0`,
		FPoint3 *	vNormal = `NULL`
	)		const

virtual

Simple elevation test for perfectly regular grid terrain. Find altitude (y) and (optionally) surface normal, given (x,z) world coordinates.

This approach is very straightforward, so it could be significantly sped up if needed.

Parameters

p	A 3D point in world coordinates. Only the X and Z values are used.
fAltitude	If the test succeeds, this contains the result by reference.
bTrue	Pass true to the use the true elevation, false to consider the vertical exaggeration in effect.
iCultureFlags	Pass 0 to test only the heightfield itself, non-zero to test any culture objects which may be sitting on the heightfield. Values include: CE_STRUCTURES Test structures on the ground. CE_ROADS Test roads on the ground. CE_ALL Test everything on the ground.
vNormal	If you pass a pointer to a vector, it will be filled in with the upwards-pointing surface normal at the given point.

Returns: true if the point was inside the elevation grid, false if outside.

Implements vtHeightField3d.

bool vtElevationGrid::FindAltitudeOnEarth	(	const DPoint2 &	p,
		float &	fAltitude,
		bool	bTrue = `false`
	)		const

virtual

Return the elevation value at a given point in earth coordinates.

Parameters

p	A 2D point in earth coordinates.
fAltitude	If the test succeeds, this contains the result by reference.
bTrue	Pass true to the use the true elevation, false to consider the vertical exaggeration in effect.

Returns: true if the point was inside the elevation grid, false if outside.

Implements vtHeightField.

void vtElevationGrid::FreeData ( )

Free any memory being used by this class for elevation data.

DRECT vtElevationGrid::GetAreaExtents ( ) const

Returns the geographic extents of the area covered by grid.

The standard extents of an elevation grid are the min and max of its data points. However, because each point in the grid is a spot elevation that implies the elevation of the ground around itself, the area over which the elevation could be understood to describe is actually half a heixel larger in each direction. This method returns that larger area.

float vtElevationGrid::GetClosestValue ( const DPoint2 & p ) const

Get the height of the grid at a specific world coordinate (nearest neighbor)

The value of the gridpoint closest to the specified location is returned. If the location is not within the extents of the grid, INVALID_ELEVATION is returned.

Parameters

p	The point to query.

const char* vtElevationGrid::GetDEMName ( )

inline

Return the embedded name of the DEM is it has one

float vtElevationGrid::GetFilteredValue ( const DPoint2 & p ) const

Get the interpolated height of the grid at a specific world coordinate.

The value is linearly interpolated between the surrounding gridpoints. If the location is not within the extents of the grid, INVALID_ELEVATION is returned. The height field has a 0.5 pixel safety boundary to catch all samples on the edges.

Parameters

p	The point to query.

float vtElevationGrid::GetFValue	(	int	i,
		int	j
	)		const

Get an elevation value from the grid.

Parameters

i,j	Column and row location in the grid.

Returns: The value in (float) meters.

short vtElevationGrid::GetShortValue	(	int	i,
		int	j
	)		const

Get a value direct from the grid, in the special case where the grid is composed of short integers with no scaling.

Parameters

i,j	Column and row location in the grid.

Returns: The value of the grid.

void vtElevationGrid::Invalidate ( )

Set all the values in the grid to INVALID_ELEVATION.

bool vtElevationGrid::IsFloatMode ( ) const

inline

Get the data size of the grid heixels (height elements): true if floating point (4-byte), false if integer (2-byte).

bool vtElevationGrid::LoadBTHeader	(	const char *	szFileName,
		vtElevError *	err = `NULL`
	)

Loads just the header information from a BT (Binary Terrain) file.

: This can be useful if you want to check the information such as the size of the data, without reading the entire file. This method works whether it is given a normal BT file, or one which has been compressed with gzip.

Returns: true if the header was successfully parsed.

bool vtElevationGrid::LoadFrom3TX	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`
	)

Loads from a 3TX ascii grid file. Projection is Geo WGS84, extents are always 1 degree in size.

You should call SetupLocalCS() after loading if you will be doing heightfield operations on this grid.

Returns: true if the file was successfully opened and read.

bool vtElevationGrid::LoadFromASC	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`
	)

Loads from a Arc/Info compatible ASCII grid file. Projection is read from a corresponding .prj file.

You should call SetupLocalCS() after loading if you will be doing heightfield operations on this grid.

Returns: true if the file was successfully opened and read.

bool vtElevationGrid::LoadFromBT	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`,
		vtElevError *	err = `NULL`
	)

Loads from a BT (Binary Terrain) file.

: Both the current version (1.1) and older BT versions are supported. This method works whether it is given a normal BT file, or one which has been compressed with gzip.

Returns: true if the file was successfully opened and read.

bool vtElevationGrid::LoadFromDEM	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`,
		vtElevError *	err = `NULL`
	)

Loads elevation from a USGS DEM file.

Some non-standard variations of the DEM format are supported.

You should call SetupLocalCS() after loading if you will be doing heightfield operations on this grid.

Returns: true if the file was successfully opened and read.

bool vtElevationGrid::LoadFromDSAA	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`
	)

Helper function for LoadFromGRD, loads from a Surfer ascii grid file (GRD)

Projection is always geographic and elevation is floating-point.

Returns: true if the file was successfully opened and read.

bool vtElevationGrid::LoadFromDTED	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`
	)

Loads from a DTED file.

: Should support DTED0, DTED1 and DTED2 files, although it has only been tested on DTED0. Projection is assumed to be geographic and elevation is integer meters.

You should call SetupLocalCS() after loading if you will be doing heightfield operations on this grid.

Returns: true if the file was successfully opened and read.

bool vtElevationGrid::LoadFromFile	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`,
		vtElevError *	err = `NULL`
	)

Load from a file whose type is not known a priori. This will end up calling one of the Load* member functions.

You should call SetupLocalCS() after loading if you will be doing heightfield operations on this grid.

Returns: true if successful.

bool vtElevationGrid::LoadFromGLOBE	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`
	)

Loads from a NOAA GlOBE file.

In fact, there is no "GLOBE format", GLOBE files are delivered as raw data, which can be intepreted using a variety of separate header files. Using the GLOBE server "Select Your Own Area" feature results in 2 files, a header with a .hdr extension and data with a .bin extension. This method reads those file. Pass the filename of the .hdr file to this function, and it will automatically look for a corresponding .bin file in the same location.

Projection is always geographic and elevation is integer meters.

You should call SetupLocalCS() after loading if you will be doing heightfield operations on this grid.

Returns: true if the file was successfully opened and read.

bool vtElevationGrid::LoadFromGRD	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`
	)

Loads from a Surfer binary grid file (GRD)

GRD does not contain any information about CRS, so the following assumption is made: UTM zone 1.

You should call SetupLocalCS() after loading if you will be doing heightfield operations on this grid.

Returns: true if the file was successfully opened and read.

bool vtElevationGrid::LoadFromGTOPO30	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`
	)

Loads from a GTOPO30 (or SRTM30) file.

GTOPO30 files are actually composed of at least 2 files, a header with a .hdr extension and data with a .dem extension. Pass the filename of the .hdr file to this function, and it will automatically look for a corresponding .dem file in the same location.

Projection is always geographic and elevation is integer meters.

You should call SetupLocalCS() after loading if you will be doing heightfield operations on this grid.

Returns: true if the file was successfully opened and read.

bool vtElevationGrid::LoadFromHGT	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`
	)

Loads from an "HGT" file, which is the format used by the USGS SRTM FTP site for their 1-degree blocks of SRTM data. It is simply a raw block of signed 2-byte data, in WGS84 geographic coords.

The file will either be: 2,884,802 bytes (for 3 arcsec, 1201*1201) or 25,934,402 bytes (for 1 arcsec, 3601*3601)

You should call SetupLocalCS() after loading if you will be doing heightfield operations on this grid.

Returns: true if the file was successfully opened and read.

bool vtElevationGrid::LoadFromMicroDEM	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`
	)

Loads from a MicroDEM format file.

You should call SetupLocalCS() after loading if you will be doing heightfield operations on this grid.

Returns: true if the file was successfully opened and read.

bool vtElevationGrid::LoadFromNTF5	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`
	)

Loads an elevation grid from an UK Ordnance Survey NTF level 5 file using the OGR library.

Parameters

szFileName	The file name to read from.
progress_callback	If supplied, this function will be called back with a value of 0 to 100 as the operation progresses.

You should call SetupLocalCS() after loading if you will be doing heightfield operations on this grid.

Returns: True if the file was successfully opened and read.

bool vtElevationGrid::LoadFromPGM	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`
	)

Loads from a PGM (Portable Gray Map) file. Both PGM Binary and ASCII varieties are supported.

PGM does not contain any information about geographic location, so the following assumptions are made: UTM coordinates, 1-meter spacing, origin at (0,0).

You should call SetupLocalCS() after loading if you will be doing heightfield operations on this grid.

Returns: true if the file was successfully opened and read.

bool vtElevationGrid::LoadFromRAW	(	const char *	szFileName,
		int	width,
		int	height,
		int	bytes_per_element,
		float	vertical_units,
		bool	bBigEndian,
		bool	progress_callbackint
	)

Loads from a RAW file (a naked array of elevation values). The file will not contain any information about at all about data size, data type, or projection, so this information must be passed in as arguments.

Parameters

szFileName	The file name to read from.
width	The width of the expected array.
height	The height of the expected array.
bytes_per_element	The number of bytes for each elevation value. If this is 1 or 2, the data is assumed to be integer. If 4, then the data is assumed to be floating-point values.
vertical_units	Indicates what scale factor to apply to the elevation values to convert them to meters. E.g. if the file is in meters, pass 1.0, if in feet, pass 0.3048.
bBigEndian	True for Big-endian byte order, false for Little-endian (Intel byte order).
progress_callback	If supplied, this function will be called back with a value of 0 to 100 as the operation progresses.

Returns: true if the file was successfully opened and read.

bool vtElevationGrid::LoadFromTerragen	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`
	)

Loads from a Terragen Terrain file.

You should call SetupLocalCS() after loading if you will be doing heightfield operations on this grid.

Returns: true if the file was successfully opened and read.

bool vtElevationGrid::LoadFromXYZ	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`
	)

Loads from an "XYZ file", which is a simple text file containing a set of grid points in the form X,Y,Z - where X and Y are ground coordinates, and Z is elevation. The values may be separated either by commas (X, Y, Z) or by whitespace (X Y Z).

Returns: true if the file was successfully opened and read.

bool vtElevationGrid::LoadWithGDAL	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`,
		vtElevError *	err = `NULL`
	)

Loads an elevation grid using the GDAL library. The GDAL library supports a very large number of formats, including SDTS-DEM. See http://www.remotesensing.org/gdal/formats_list.html for the complete list of GDAL-supported formats.

Parameters

szFileName	The file name to read from.
progress_callback	If supplied, this function will be called back with a value of 0 to 100 as the operation progresses.
err	If supplied, will be set to a description of any error that occurs.

You should call SetupLocalCS() after loading if you will be doing heightfield operations on this grid.

Returns: True if the file was successfully opened and read.

void vtElevationGrid::Offset ( const DPoint2 & delta )

Offset the entire elevation grid horizontally.

Parameters

delta The X,Y amount to shift the location of the grid.

vtElevationGrid & vtElevationGrid::operator= ( const vtElevationGrid & rhs )

Assignment operator.

Returns: *this with new values

int vtElevationGrid::ReplaceValue	(	float	value1,
		float	value2
	)

Replace one value with another. For example, replace all heixels of value INVALID_ELEVATION with 0.0.

Parameters

value1	The heixel value to replace.
value2	The value to replace it with.

Returns: The number of heixels that were modified.

bool vtElevationGrid::ReprojectExtents ( const vtCRS & proj_new )

Reprojects an elevation grid by converting just the extents to a new projection.

This is much faster than creating a new grid and reprojecting every heixel, but it only produces correct results when the difference between the projections is only a horizontal shift. For example, this occurs when the only difference between the old and new projection is choice of Datum.

Parameters

proj_new The new projection to convert to.

Returns: True if successful.

bool vtElevationGrid::SaveToASC	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`
	)		const

Writes an Arc/Info compatible ASCII grid file. Projection is written to a corresponding .prj file.

Returns: true if the file was successfully opened and written.

bool vtElevationGrid::SaveToBT	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`,
		bool	bGZip = `false`
	)

Writes the grid to a BT (Binary Terrain) file. The current BT format version (1.3) is written.

Parameters

szFileName	The file name to write to.
progress_callback	If supplied, this function will be called back with a value of 0 to 100 as the operation progresses.
bGZip	If true, the data will be compressed with gzip. If true, you should Use a filename ending with ".gz".

bool vtElevationGrid::SaveToGeoTIFF ( const char * szFileName ) const

Write the elevation grid to a 16-bit greyscale GeoTIFF.

bool vtElevationGrid::SaveToPlanet	(	const char *	szDirName,
		bool	progress_callbackint = `NULL`
	)

Write elevation to the MSI Planet (Marconi) format.

Returns: true if the file was successfully opened and written.

bool vtElevationGrid::SaveToPNG16 ( const char * fname )

Write elevation a 16-bit greyscale PNG file.

bool vtElevationGrid::SaveToRAW_Unity	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`
	)		const

Write elevation to a .raw file, the way Unity import expects it: Scaled to 8 bits (0-255).

bool vtElevationGrid::SaveToRAWINF	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`
	)		const

Write elevation to a .raw file along with an .inf file which describes the data for the purpose of exporting to MS Flight Simulator 2004 via their MSFS SDK 'resample' utility.

Parameters

szFileName	Should end in ".raw"
progress_callback	If supplied, this function will be called back with a value of 0 to 100 as the operation progresses.

Returns: true if the file was successfully written.

bool vtElevationGrid::SaveToSTM	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`
	)

Write elevation to the STM (Simple Terrain Model) format created by Michael Garland for his 'Scape' Terrain Simplification software.

Returns: true if the file was successfully opened and written.

bool vtElevationGrid::SaveToTerragen ( const char * szFileName ) const

Writes the grid to a TerraGen Terrain file.

Parameters

szFileName The filename to write to.

bool vtElevationGrid::SaveToVRML	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`
	)		const

Write elevation to a VRML file which contains a single ElevationGrid node.

Returns: true if the file was successfully opened and written.

bool vtElevationGrid::SaveToXYZ	(	const char *	szFileName,
		bool	progress_callbackint = `NULL`
	)		const

Write elevation to a text file which contains an XYZ for each point.

Returns: true if the file was successfully opened and written.

void vtElevationGrid::Scale	(	float	fScale,
		bool	bDirect,
		bool	bRecomputeExtents = `true`
	)

Scale all the valid elevation values in the grid by a given factor.

Parameters

fScale	The desired scale, e.g. 1.0 produces no change in scale.
bDirect	If true, scale the stored height values directly. Otherwise, only the height scale (vertical meters per unit) is scaled.
bRecomputeExtents	If true, recompute the height extents. Default is true.

void vtElevationGrid::SetFValue	(	int	i,
		int	j,
		float	value
	)

Set an elevation value to the grid.

Parameters

i,j	Column and row location in the grid.
value	The value in (float) meters.

void vtElevationGrid::SetupLocalCS ( float fVerticalExag = 1.0f )

Set up the terrain's coordinate systems, including the conversion from Earth coordinates to the World coordinates of the terrain itself. You should call this method after loading or creating a vtElevationGrid, before using methods on it such as FindAltitudeOnEarth or GetSpacing.

For explanation of vtlib/vtdata world coordinates, please see http://vterrain.org/Doc/coords.html

Parameters

fVerticalExag The vertical exaggeration of the terrain, which is how many times higher it should appear than it really is. Pass 1.0 for no exaggeration.

void vtElevationGrid::SetValue	(	int	i,
		int	j,
		short	value
	)

Set an elevation value to the grid.

Parameters

i,j	Column and row location in the grid.
value	The value in (integer) meters.

void vtElevationGrid::VertOffset ( float fAmount )

Vertically offset the valid elevation values in the grid by a given amount.

Parameters

fAmount The amount to be added to every elevation value.

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