/****************************************************************************** * * Project: Natural Resources Canada's Geoid BYN file format * Purpose: Implementation of BYN format * Author: Ivan Lucena, ivan.lucena@outlook.com * ****************************************************************************** * Copyright (c) 2018, Ivan Lucena * Copyright (c) 2018, Even Rouault * * SPDX-License-Identifier: MIT ****************************************************************************/ #ifndef GDAL_FRMTS_RAW_BYNDATASET_H_INCLUDED #define GDAL_FRMTS_RAW_BYNDATASET_H_INCLUDED #include "cpl_port.h" #include "rawdataset.h" /****************************************************************************** Format specification ****************************************************************************** Table 1: Header description (80 bytes) # Variable Description Type Byte Sum Comments/(Units) --:-----------:------------------:------:----:---:--------------------------- 1 South South Boundary long 4 4 (arcsec.) 2 North North Boundary long 4 8 (arcsec.) 3 West West Boundary long 4 12 (arcsec.) 4 East East Boundary long 4 16 (arcsec.) 5 DLat NS Spacing long 2 18 (arcsec.) 6 DLon EW Spacing short 2 20 (arcsec.) 7 Global Global short 2 22 0: Local/Regional/National grid 1: Global grid 8 Type Type short 2 24 See Table 2 9 Factor Data factor double 8 32 Transform data from integer to real 10 SizeOf Data size in bytes short 2 34 2: short integer 4: long integer 11 VDatum Vertical Datum short 2 36 0: Unspecified 1: CGVD28 2: CGVD2013 3: NAVD 88 12 Spare 6 40 Always zero 13 Data Data description short 2 42 0: Data (e.g., N) 1: Data error estimates (e.g., .N) 2: Data velocity (e.g., N-dot) 3: Velocity error estimates (e.g., .N-dot) 14 SubType Sub-Type short 2 44 See table 2 below 15 Datum 3-D Ref. Frame short 2 46 0: ITRF / WGS84 1: NAD83(CSRS) 16 Ellipsoid Ellipsoid short 2 48 See Table 3 17 ByteOrder Byte Order short 2 50 0: Big-endian (e.g., HP Unix) 1: Little-endian (e.g., PC, linux) 18 Scale Scale Boundaries short 2 52 0: No scale applied to boundaries and spacing 1: Scale is applied (x1000) 19 Wo Geopotential Wo double 8 60 2ms-2 (e.g., W = 62636856.88) 20 GM GM double 8 68 3ms-2 (e.g., GM = 3.986 E 14) 21 TideSystem Tidal System short 2 70 0: Tide free 1: Mean tide 2: Zero tide 22 RefRealiz. Realization (3D) short 2 72 Version number (e.g., 2005 for ITRF) 23 Epoch Epoch float 4 76 Decimal year (e.g., 2007.5) 24 PtType Node short 2 78 0: Point 1: Mean 25 Spare 2 80 Always zero --:-----------:------------------:------:----:---:--------------------------- Items #18 to 22 must be defined if the grid is a geoid model. Table 2: Sub-Type # Type (item #8) # Sub-Type (item #13) -:------------------------------:-:---------------------------------- 0 Undefined 0 NULL 1 Ellipsoid-Potential separation 0 Geoid Height 1 Height Anomaly 2 Height Transformation (Hybrid) 2 Deflections of the vertical NS 0 NULL 3 Deflections of the vertical EW 0 NULL 4 Gravity 0 Undefined 1 Absolute (m s**-2 instead of mGal) 2 Free-Air 3 Bouguer 4 Complete Bouguer 5 Helmert 6 Isostatic 5 DEM 0 MSL (General) 1 Orthometric 2 Normal 3 Dynamic 4 Ellipsoidal 6 Sea Surface Height (SSH) 0 NULL 7 Sea Surface Topography (SST) 0 NULL 8 Ocean current velocity 0 NULL 9 Others 0 NULL -:------------------------------:-:---------------------------------- Table 3: Ellipsoids # Name Semi-major (m) Inverse flattening GM (m3s2) Angular velocity (rads s**-1) -:-------:---------------:-------------------:---------------:----------------------------- 0 GRS80 6378137.0 298.257222101 3986005.0 E 8 7292115 E -11 1 WGS84 6378137.0 298.257223564 3986004.418 E 8 7292115 E -11 2 ALT1 6378136.3 298.256415099 3986004.415 E 8 7292115 E -11 3 GRS67 6378160.0 298.247167427 3986030.0 E 8 7292115.1467 E -11 4 ELLIP1 6378136.46 298.256415099 3986004.415 E 8 7292115 E -11 5 ALT2 6378136.3 298.257 3986004.415 E 8 7292115 E -11 6 ELLIP2 6378136.0 298.257 3986004.4 E 8 7292115 E -11 7 CLARKE 1866 6378206.4 294.9786982 3986004.4 E 8 7292115 E -11 Data (Row x Column x byte size) The data are stored by rows starting from the north. Each row is stored from the west to the east. The data are either short (2 bytes) or long (4 bytes) integers. The size of the bytes is defined in the header (item #10). The total size of the file is 80 bytes + (Row x Column x (2 or 4) bytes) where Row = (North - South)/nDLat + 1 and Column = (East - West)/DLon + 1 Undefined values Long int (4-byte data): 9999.0*Factor Short int (2 byte data): 32767 ****************************************************************************/ /************************************************************************/ /* BYNHeader */ /************************************************************************/ constexpr int BYN_HDR_SZ = 80; /* != sizeof(BYNHeader) */ /* "Spare" fields are not represented here, no direct read/write */ struct BYNHeader { GInt32 nSouth; GInt32 nNorth; GInt32 nWest; GInt32 nEast; GInt16 nDLat; GInt16 nDLon; GInt16 nGlobal; GInt16 nType; double dfFactor; GInt16 nSizeOf; GInt16 nVDatum; GInt16 nDescrip; GInt16 nSubType; GInt16 nDatum; GInt16 nEllipsoid; GInt16 nByteOrder; GInt16 nScale; double dfWo; double dfGM; GInt16 nTideSys; GInt16 nRealiz; float dEpoch; GInt16 nPtType; }; struct BYNEllipsoids { const char *pszName; double dfSemiMajor; double dfInvFlattening; }; /* Recognizeble EPSG codes */ constexpr int BYN_DATUM_1_VDATUM_2 = 6649; /* Compounded NAD83(CSRS) + CGVD2013 */ constexpr int BYN_DATUM_0 = 4140; /* ITRF2008 (GRS80 based WGS84) */ constexpr int BYN_DATUM_1 = 4617; /* NAD83(CSRS) */ constexpr int BYN_VDATUM_1 = 5713; /* CGVD28 */ constexpr int BYN_VDATUM_2 = 6647; /* CGVD2013 */ constexpr int BYN_VDATUM_3 = 6357; /* NAVD88 */ /* Maximum ordinates values for Identify() */ constexpr GInt32 BYN_SCALE = 1000; constexpr GInt32 BYN_MAX_LAT = 90 * 3600 * 2; constexpr GInt32 BYN_MAX_LON = 180 * 3600 * 2; constexpr GInt32 BYN_MAX_LAT_SCL = BYN_MAX_LAT / BYN_SCALE; constexpr GInt32 BYN_MAX_LON_SCL = BYN_MAX_LON / BYN_SCALE; /************************************************************************/ /* ==================================================================== */ /* BYNDataset */ /* ==================================================================== */ /************************************************************************/ class BYNDataset final : public RawDataset { friend class BYNRasterBand; VSILFILE *fpImage; double adfGeoTransform[6]; mutable OGRSpatialReference m_oSRS{}; BYNHeader hHeader; void UpdateHeader(); CPL_DISALLOW_COPY_ASSIGN(BYNDataset) static void header2buffer(const BYNHeader *pohHeader, GByte *pabyBuf); static void buffer2header(const GByte *pabyBuf, BYNHeader *pohHeader); CPLErr Close() override; public: BYNDataset(); ~BYNDataset(); CPLErr GetGeoTransform(double *padfTransform) override; CPLErr SetGeoTransform(double *padfTransform) override; const OGRSpatialReference *GetSpatialRef() const override; CPLErr SetSpatialRef(const OGRSpatialReference *poSRS) override; static GDALDataset *Open(GDALOpenInfo *); static int Identify(GDALOpenInfo *); static GDALDataset *Create(const char *pszFilename, int nXSize, int nYSize, int nBands, GDALDataType eType, char **papszOptions); }; /************************************************************************/ /* ==================================================================== */ /* BYNRasterBand */ /* ==================================================================== */ /************************************************************************/ class BYNRasterBand final : public RawRasterBand { friend class BYNDataset; CPL_DISALLOW_COPY_ASSIGN(BYNRasterBand) public: BYNRasterBand(GDALDataset *poDS, int nBand, VSILFILE *fpRaw, vsi_l_offset nImgOffset, int nPixelOffset, int nLineOffset, GDALDataType eDataType, int bNativeOrder); ~BYNRasterBand() override; double GetNoDataValue(int *pbSuccess = nullptr) override; double GetScale(int *pbSuccess = nullptr) override; CPLErr SetScale(double dfNewValue) override; }; #endif // GDAL_FRMTS_RAW_BYNDATASET_H_INCLUDED