OGRSpatialReference* OGRGetGeomediaSRS(OGRFeature* poFeature)
{
if (poFeature == NULL)
return NULL;
int nGeodeticDatum = poFeature->GetFieldAsInteger("GeodeticDatum");
int nEllipsoid = poFeature->GetFieldAsInteger("Ellipsoid");
int nProjAlgorithm = poFeature->GetFieldAsInteger("ProjAlgorithm");
if (nGeodeticDatum == 17 && nEllipsoid == 22)
{
if (nProjAlgorithm == 12)
{
OGRSpatialReference* poSRS = new OGRSpatialReference();
const char* pszDescription = poFeature->GetFieldAsString("Description");
if (pszDescription && pszDescription[0] != 0)
poSRS->SetNode( "PROJCS", pszDescription );
poSRS->SetWellKnownGeogCS("WGS84");
double dfStdP1 = poFeature->GetFieldAsDouble("StandPar1");
double dfStdP2 = poFeature->GetFieldAsDouble("StandPar2");
double dfCenterLat = poFeature->GetFieldAsDouble("LatOfOrigin");
double dfCenterLong = poFeature->GetFieldAsDouble("LonOfOrigin");
double dfFalseEasting = poFeature->GetFieldAsDouble("FalseX");
double dfFalseNorthing = poFeature->GetFieldAsDouble("FalseY");
poSRS->SetACEA( dfStdP1, dfStdP2,
dfCenterLat, dfCenterLong,
dfFalseEasting, dfFalseNorthing );
return poSRS;
}
}
return NULL;
}
int USGSDEMDataset::LoadFromFile(VSILFILE *InDem)
{
// check for version of DEM format
CPL_IGNORE_RET_VAL(VSIFSeekL(InDem, 864, 0));
// Read DEM into matrix
const int nRow = ReadInt(InDem);
const int nColumn = ReadInt(InDem);
const bool bNewFormat = VSIFTellL(InDem) >= 1024 || nRow != 1 || nColumn != 1;
if (bNewFormat)
{
CPL_IGNORE_RET_VAL(VSIFSeekL(InDem, 1024, 0)); // New Format
int i = ReadInt(InDem);
int j = ReadInt(InDem);
if ( i != 1 || ( j != 1 && j != 0 ) ) // File OK?
{
CPL_IGNORE_RET_VAL(VSIFSeekL(InDem, 893, 0)); // Undocumented Format (39109h1.dem)
i = ReadInt(InDem);
j = ReadInt(InDem);
if ( i != 1 || j != 1 ) // File OK?
{
CPLError( CE_Failure, CPLE_AppDefined,
"Does not appear to be a USGS DEM file." );
return FALSE;
}
else
nDataStartOffset = 893;
}
else
nDataStartOffset = 1024;
}
else
nDataStartOffset = 864;
CPL_IGNORE_RET_VAL(VSIFSeekL(InDem, 156, 0));
const int nCoordSystem = ReadInt(InDem);
const int iUTMZone = ReadInt(InDem);
CPL_IGNORE_RET_VAL(VSIFSeekL(InDem, 528, 0));
const int nGUnit = ReadInt(InDem);
const int nVUnit = ReadInt(InDem);
// Vertical Units in meters
if (nVUnit==1)
pszUnits = "ft";
else
pszUnits = "m";
CPL_IGNORE_RET_VAL(VSIFSeekL(InDem, 816, 0));
const double dxdelta = DConvert(InDem, 12);
const double dydelta = DConvert(InDem, 12);
if( dydelta == 0 )
return FALSE;
fVRes = DConvert(InDem, 12);
/* -------------------------------------------------------------------- */
/* Should we treat this as floating point, or GInt16. */
/* -------------------------------------------------------------------- */
if (nVUnit==1 || fVRes < 1.0)
eNaturalDataFormat = GDT_Float32;
else
eNaturalDataFormat = GDT_Int16;
/* -------------------------------------------------------------------- */
/* Read four corner coordinates. */
/* -------------------------------------------------------------------- */
CPL_IGNORE_RET_VAL(VSIFSeekL(InDem, 546, 0));
DPoint2 corners[4]; // SW, NW, NE, SE
for (int i = 0; i < 4; i++)
{
corners[i].x = DConvert(InDem, 24);
corners[i].y = DConvert(InDem, 24);
}
// find absolute extents of raw vales
DPoint2 extent_min, extent_max;
extent_min.x = std::min(corners[0].x, corners[1].x);
extent_max.x = std::max(corners[2].x, corners[3].x);
extent_min.y = std::min(corners[0].y, corners[3].y);
extent_max.y = std::max(corners[1].y, corners[2].y);
/* dElevMin = */ DConvert(InDem, 48);
/* dElevMax = */ DConvert(InDem, 48);
CPL_IGNORE_RET_VAL(VSIFSeekL(InDem, 858, 0));
const int nProfiles = ReadInt(InDem);
/* -------------------------------------------------------------------- */
/* Collect the spatial reference system. */
/* -------------------------------------------------------------------- */
OGRSpatialReference sr;
bool bNAD83 = true;
// OLD format header ends at byte 864
if (bNewFormat)
{
// year of data compilation
CPL_IGNORE_RET_VAL(VSIFSeekL(InDem, 876, 0));
char szDateBuffer[5];
CPL_IGNORE_RET_VAL(VSIFReadL(szDateBuffer, 4, 1, InDem));
/* szDateBuffer[4] = 0; */
// Horizontal datum
// 1=North American Datum 1927 (NAD 27)
// 2=World Geodetic System 1972 (WGS 72)
// 3=WGS 84
// 4=NAD 83
// 5=Old Hawaii Datum
// 6=Puerto Rico Datum
CPL_IGNORE_RET_VAL(VSIFSeekL(InDem, 890, 0));
char szHorzDatum[3];
CPL_IGNORE_RET_VAL(VSIFReadL( szHorzDatum, 1, 2, InDem ));
szHorzDatum[2] = '\0';
const int datum = atoi(szHorzDatum);
switch (datum)
{
case 1:
sr.SetWellKnownGeogCS( "NAD27" );
bNAD83 = false;
break;
case 2:
sr.SetWellKnownGeogCS( "WGS72" );
break;
case 3:
sr.SetWellKnownGeogCS( "WGS84" );
break;
case 4:
sr.SetWellKnownGeogCS( "NAD83" );
break;
case -9:
break;
default:
sr.SetWellKnownGeogCS( "NAD27" );
break;
}
}
else
{
sr.SetWellKnownGeogCS( "NAD27" );
bNAD83 = false;
}
if (nCoordSystem == 1) // UTM
{
if( iUTMZone >= -60 && iUTMZone <= 60 )
{
sr.SetUTM( abs(iUTMZone), iUTMZone >= 0 );
if( nGUnit == 1 )
{
sr.SetLinearUnitsAndUpdateParameters( SRS_UL_US_FOOT, CPLAtof(SRS_UL_US_FOOT_CONV) );
char szUTMName[128];
snprintf( szUTMName, sizeof(szUTMName), "UTM Zone %d, Northern Hemisphere, us-ft", iUTMZone );
sr.SetNode( "PROJCS", szUTMName );
}
}
}
else if (nCoordSystem == 2) // state plane
{
if( nGUnit == 1 )
sr.SetStatePlane( iUTMZone, bNAD83,
"Foot", CPLAtof(SRS_UL_US_FOOT_CONV) );
else
sr.SetStatePlane( iUTMZone, bNAD83 );
}
sr.exportToWkt( &pszProjection );
/* -------------------------------------------------------------------- */
/* For UTM we use the extents (really the UTM coordinates of */
/* the lat/long corners of the quad) to determine the size in */
/* pixels and lines, but we have to make the anchors be modulus */
/* the pixel size which what really gets used. */
/* -------------------------------------------------------------------- */
if (nCoordSystem == 1 // UTM
|| nCoordSystem == 2 // State Plane
|| nCoordSystem == -9999 ) // unknown
{
// expand extents modulus the pixel size.
extent_min.y = floor(extent_min.y/dydelta) * dydelta;
extent_max.y = ceil(extent_max.y/dydelta) * dydelta;
// Forcibly compute X extents based on first profile and pixelsize.
CPL_IGNORE_RET_VAL(VSIFSeekL(InDem, nDataStartOffset, 0));
/* njunk = */ ReadInt(InDem);
/* njunk = */ ReadInt(InDem);
/* njunk = */ ReadInt(InDem);
/* njunk = */ ReadInt(InDem);
const double dxStart = DConvert(InDem, 24);
nRasterYSize = static_cast<int>(
( extent_max.y - extent_min.y ) / dydelta + 1.5 );
nRasterXSize = nProfiles;
adfGeoTransform[0] = dxStart - dxdelta/2.0;
adfGeoTransform[1] = dxdelta;
adfGeoTransform[2] = 0.0;
adfGeoTransform[3] = extent_max.y + dydelta/2.0;
adfGeoTransform[4] = 0.0;
adfGeoTransform[5] = -dydelta;
}
/* -------------------------------------------------------------------- */
/* Geographic -- use corners directly. */
/* -------------------------------------------------------------------- */
else
{
nRasterYSize = static_cast<int>(
( extent_max.y - extent_min.y ) / dydelta + 1.5 );
nRasterXSize = nProfiles;
// Translate extents from arc-seconds to decimal degrees.
adfGeoTransform[0] = (extent_min.x - dxdelta/2.0) / 3600.0;
adfGeoTransform[1] = dxdelta / 3600.0;
adfGeoTransform[2] = 0.0;
adfGeoTransform[3] = (extent_max.y + dydelta/2.0) / 3600.0;
adfGeoTransform[4] = 0.0;
adfGeoTransform[5] = (-dydelta) / 3600.0;
}
if (!GDALCheckDatasetDimensions(nRasterXSize, nRasterYSize))
{
return FALSE;
}
return TRUE;
}