vtHeightFieldGrid3d Class Reference

Inheritance diagram for vtHeightFieldGrid3d:

[legend]List of all members.

Public Member Functions
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
DPoint2	GetSpacing () const
FPoint2	GetWorldSpacing () const
void	GetDimensions (int &nColumns, int &nRows) const
void	EarthToGrid (const DPoint2 &epos, IPoint2 &ipos)
void	WorldToGrid (const FPoint3 &pos, IPoint2 &ipos)
float	GetInterpolatedElevation (double findex_x, double findex_y) const
int	FindNumUnknown ()
virtual float	GetElevation (int iX, int iZ, bool bTrue=false) const =0
virtual void	GetWorldLocation (int i, int j, FPoint3 &loc, bool bTrue=false) const =0
bool	ColorDibFromElevation (vtBitmapBase *pBM, const ColorMap *cmap, int iGranularity, const RGBAi &nodata, bool progress_callback(int)=NULL)
bool	ColorDibFromTable (vtBitmapBase *pBM, std::vector< RGBi > &table, float fMin, float fMax, const RGBAi &nodata, bool progress_callback(int)=NULL)
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)
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)
Protected Attributes
int	m_iColumns
int	m_iRows
float	m_fXStep
float	m_fZStep
double	m_dXStep
double	m_dYStep

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Detailed Description

This class extends vtHeightField3d with the knowledge of operating on a regular grid of elevation values.

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Member Function Documentation

bool vtHeightFieldGrid3d::CastRayToSurface (  const FPoint3 &  point, const FPoint3 &  dir, FPoint3 &  result )  const [virtual]

Tests a ray against a heightfield grid. Note: This algorithm is not guaranteed to give absolutely correct results, but it is reasonably fast and efficient. It checks a series of points along the ray against the terrain. When a pair of points (segment) is found to straddle the terrain, it refines the segment in a binary fashion. Since the length of the test is proportional to a single grid element, there is a small chance that it will give results that are off by a small distance (less than 1 grid element) Returns: true if hit terrain. The resulting point of intersection is placed in the 'result' argument. Implements vtHeightField3d.

bool vtHeightFieldGrid3d::ColorDibFromElevation (  vtBitmapBase *  pBM, const ColorMap *  cmap, int  iGranularity, const RGBAi &  nodata, bool   progress_callback(int) = NULL )

Use the height data in the grid to fill a bitmap with colors. Parameters: pBM  The bitmap to be colored. cmap  The mapping of elevation values to colors. iGranularity  The smoothness of the mapping, expressed as the size of the internal mapping table. 2000 is a generally good value. nodata  The color to use for NODATA areas, where there are no elevation values. progress_callback  If supplied, this function will be called back with a value of 0 to 100 as the operation progresses. Returns: true if any invalid elevation values were encountered.

bool vtHeightFieldGrid3d::ColorDibFromTable (  vtBitmapBase *  pBM, std::vector< RGBi > &  table, float  fMin, float  fMax, const RGBAi &  nodata, bool   progress_callback(int) = NULL )

Use the height data in the grid and a colormap fill a bitmap with colors. Any undefined heixels in the source will be fill with red (255,0,0). Parameters: pBM  The bitmap to be colored. table  The table of colors. fMin,fMax  The range of valid elevation values expect in the input. nodata  The color to use for NODATA areas, where there are no elevation values. progress_callback  If supplied, this function will be called back with a value of 0 to 100 as the operation progresses. Returns: true if any invalid elevation values were encountered.

void vtHeightFieldGrid3d::EarthToGrid (  const DPoint2 &  epos, IPoint2 &  ipos )

Convert a point from earth coordinates to the integer coordinates of the grid.

int vtHeightFieldGrid3d::FindNumUnknown (   )

Count the number of unknown (invalid) heixels in this grid.

void vtHeightFieldGrid3d::GetDimensions (  int &  nColumns, int &  nRows )  const

Get the grid size of the grid. The values are placed into the arguments by reference. Parameters: nColumns  The number of columns (east-west) nRows  THe number of rows (north-south)

float vtHeightFieldGrid3d::GetInterpolatedElevation (  double  findex_x, double  findex_y )  const

Get the interpolated height of the grid at a specific grid coordinate, where the coordinates can be non-integer; the result is interpolated between the source heixels when possible (i.e. not at the edge) Parameters: findex_x  Floating point index, from 0 to width in heixels. findex_y  Floating point index, from 0 to height in heixels.

DPoint2 vtHeightFieldGrid3d::GetSpacing (   )  const

Get the grid spacing, the width of each column and row.

bool vtHeightFieldGrid3d::LineOfSight (  const FPoint3 &  point1, const FPoint3 &  point2 )  const

Returns: true if a line of sight exists between point1 and point2.

void vtHeightFieldGrid3d::SetEarthExtents (  const DRECT &  ext  )  [virtual]

Set the geographic extents of the grid. Reimplemented from vtHeightField3d.

void vtHeightFieldGrid3d::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 )

Perform simple shading of a bitmap, based on this grid's elevation values. Lighting is computing using the dot product of the surface normal with the light direction. This is often called "dot-product lighting". Parameters: pBM  The bitmap to shade. light_dir  Direction vector of the light. fLightFactor  Value from 0 (no shading) to 1 (full shading) fAmbient  Ambient light values from 0 to 1, a typical value is 0.1. fGamma  Gamma values from 0 to 1, values less than 1 boost the brightness curve. bTrue  If true, use the real elevation values, ignoring vertical exaggeration. progress_callback  If supplied, will be called with values from 0 to 100.

void vtHeightFieldGrid3d::ShadeQuick (  vtBitmapBase *  pBM, float  fLightFactor, bool  bTrue = false, bool   progress_callback(int) = NULL )

Quickly produce a shading-like effect by scanning over the bitmap once, using the east-west slope to produce lightening/darkening. The bitmap must be the same size as the elevation grid, or a power of 2 smaller.

void vtHeightFieldGrid3d::ShadowCastDib (  vtBitmapBase *  pBM, const FPoint3 &  light_dir, float  fLightFactor, float  fAmbient, bool   progress_callback(int) = NULL )

ShadowCastDib - method to create shadows over the terrain based on the angle of the sun. Parameters: pBM  An interface to the bitmap to be shaded. light_dir  The direction of the light, in world coordinates, coming down toward the terrain. For example, (-1,-1,0) is pointing down where the sun would be at 9AM on the equator. Despite this example, light_dir should be normalized to unit length. fLightFactor  Amount of shading, from 0 to 1. A value of 0 means no lighting, 1 means full lighting. fAmbient  Amount of ambient light, from 0 to 1. A typical value is 0.1. progress_callback  Optional callback for progress notification.

void vtHeightFieldGrid3d::WorldToGrid (  const FPoint3 &  pos, IPoint2 &  ipos )

Convert a point from world coordinates to the integer coordinates of the grid.

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