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ElevationGrid.h

//
// vtElevationGrid.h
//
// Copyright (c) 2001 Virtual Terrain Project.
// Free for all uses, see license.txt for details.
//

#ifndef ELEVATIONGRIDH
#define ELEVATIONGRIDH

#include <stdio.h>
#include <limits.h>         // for SHRT_MIN
#include "MathTypes.h"
#include "Projections.h"
#include "vtDIB.h"

#define INVALID_ELEVATION   SHRT_MIN

class vtElevationGrid 
{
public:
    vtElevationGrid();
    vtElevationGrid(DRECT area, int iColumns, int iRows, bool bFloat, vtProjection proj);
    ~vtElevationGrid();

    bool ConvertProjection(vtElevationGrid *pOld, vtProjection &NewProj, void progress_callback(int) = NULL);

    // Load
    bool LoadFromDEM(const char *szFileName, void progress_callback(int) = NULL);
    bool LoadFromASC(const char *szFileName, void progress_callback(int) = NULL);
    bool LoadFromTerragen(const char *szFileName, void progress_callback(int) = NULL);
    bool LoadFromCDF(const char *szFileName, void progress_callback(int) = NULL);
    bool LoadFromDTED(const char *szFileName, void progress_callback(int) = NULL);
    bool LoadFromGTOPO30(const char *szFileName, void progress_callback(int) = NULL);
    bool LoadFromGRD(const char *szFileName, void progress_callback(int) = NULL);
    bool LoadFromPGM(const char *szFileName, void progress_callback(int) = NULL);
    bool LoadFromRAW(const char *szFileName, int width, int height,
        int bytes_per_element, float vertical_units);
    bool LoadFromBT(const char *szFileName, void progress_callback(int) = NULL);
    bool LoadBTHeader(FILE *fp);

    // Use GDAL to read a file
    bool LoadWithGDAL(const char *szFileName, void progress_callback(int));

    // Save
    void SaveToTerragen(FILE *fp);
    void SaveToBT(FILE *fp);

    void ComputeHeightExtents();
    void GetHeightExtents(float &fMinHeight, float &fMaxHeight);
    void GetDimensions(int &nColumns, int &nRows);
    DPoint2 GetSpacing();

    bool ContainsPoint(float x, float y)
    {
        return (m_area.left < x && x < m_area.right &&
                m_area.bottom < y && y < m_area.top);
    }

    // Set/Get height values
    void  SetFValue(int i, int j, float value);
    void  SetValue(int i, int j, short value);
    int   GetValue(int i, int j);   // returns height value as a integer
    float GetFValue(int i, int j);  // returns height value as a float

    float GetClosestValue(double x, double y);
    float GetFilteredValue(double x, double y);

    // Accessors
    char *GetDEMName()  { return m_szOriginalDEMName; }

    DRECT &GetGridExtents() { return m_area; }

    DRECT GetAreaExtents();

    void SetGridExtents(DRECT &ext) { m_area = ext; }

    bool  IsFloatMode() { return m_bFloatMode; }

    void ColorDibFromElevation1(vtDIB *pDIB, RGBi color_ocean);

    vtProjection &GetProjection() { return m_proj; }

    void GetCorners(DLine2 &line, bool bGeo);
    void SetCorners(DLine2 &line);

protected:
    DRECT   m_area;     // bounds in the original data space
    int     m_iColumns;
    int     m_iRows;
    bool    m_bFloatMode;
    short   *m_pData;
    float   *m_pFData;

    void ComputeExtentsFromCorners();
    void ComputeCornersFromExtents();

    DPoint2     m_Corners[4];       // data corners, in the projection of this terrain

    vtProjection    m_proj;

private:
    // minimum and maximum height values for the whole grid
    float   m_fMinHeight, m_fMaxHeight;
    char    m_szOriginalDEMName[41];

    void    AllocateArray();

    // only used by DEM reader code
    double  m_fVMeters;
    double  m_fGRes;
    int     m_iDataSize;
};


//  Header structure for a GTOPO30 DEM header file
typedef struct  
{
    char            ByteOrder[30];      //  Byte order in which image pixel values are stored 
                                        //      M = Motorola byte order (MSB first)
    char            Layout[30];         //  Organization of the bands in the file
                                        //      BIL = Band interleaved by line (DEM = single band image)
    unsigned long   NumRows;            //  Number of rows in the image
    unsigned long   NumCols;            //  Number of columns in the image
    char            Bands[30];          //  Number of spectral bands in the image (1 for DEM)
    char            Bits[30];           //  Number of bits per pixel (16 for DEM)
    char            BandRowBytes[30];   //  Number of bytes per band per row 
                                        //      (twice the number of columns for 16 bit DEM)
    char            TotalRowBytes[30];  //  Total number of bytes of data per row
                                        //      (twice the number of columns for 16 bit DEM)
    char            BandGapBytes[30];   //  Number of bytes between bands in a BSQ format
                                        //      (0 for DEM)
    short           NoData;             //  Value used for no data or masking purposes
    double          ULXMap;             //  Longitude of the center of the upper left pixel in decimal degrees.     
    double          ULYMap;             //  Latitude of the center of the upper left pixel in decimal degrees.      
    double          XDim;               //  x dimension of a pixel in geographic units (decimal degrees).       
    double          YDim;               //  y dimension of a pixel in geographic units (decimal degrees).
} GTOPOHeader;

#ifndef max
#define max(a,b)            (((a) > (b)) ? (a) : (b))
#endif

#ifndef min
#define min(a,b)            (((a) < (b)) ? (a) : (b))
#endif

#endif  // ELEVATIONGRIDH

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