/// <summary>
/// 构造函数
/// </summary>
/// <param name="ellipsoid">椭球体</param>
/// <param name="primeMeridian">首子午线</param>
/// <param name="name">名称</param>
/// <param name="bursaParamsToWGS84">转换参数</param>
/// <param name="id">ID</param>
public GeodeticDatum(Ellipsoid ellipsoid, PrimeMeridian primeMeridian, BursaTransParams bursaParamsToWGS84 = null, string name = null, string id = null)
: base(name, id)
{
this.Ellipsoid = ellipsoid;
this.PrimeMeridian = primeMeridian;
this.TransParamsToWgs84 = bursaParamsToWGS84;
}
/// <summary>
/// Initializes a new instance of a horizontal datum
/// </summary>
/// <param name="ellipsoid">Ellipsoid</param>
/// <param name="toWgs84">Parameters for a Bursa Wolf transformation into WGS84</param>
/// <param name="type">Datum type</param>
/// <param name="name">Name</param>
/// <param name="id">Authority-specific identification code.</param>
public HorizontalDatum(
Ellipsoid ellipsoid,
BursaTransParams toWgs84,
DatumType type,
string name = null,
string id = null)
: base(type, name, id)
{
Ellipsoid = ellipsoid;
Wgs84Parameters = toWgs84;
}
/// <summary>
/// Reads either 3, 6 or 7 parameter Bursa-Wolf values from TOWGS84 token
/// </summary>
/// <param name="tokenizer"></param>
/// <returns></returns>
private static BursaTransParams ReadWGS84ConversionInfo(WktStreamTokenizer tokenizer)
{
//TOWGS84[0,0,0,0,0,0,0]
tokenizer.ReadToken("[");
BursaTransParams info = new BursaTransParams();
tokenizer.NextToken();
info.Dx = tokenizer.GetNumericValue();
tokenizer.ReadToken(",");
tokenizer.NextToken();
info.Dy = tokenizer.GetNumericValue();
tokenizer.ReadToken(",");
tokenizer.NextToken();
info.Dz = tokenizer.GetNumericValue();
tokenizer.NextToken();
if (tokenizer.GetStringValue() == ",")
{
tokenizer.NextToken();
info.Ex = tokenizer.GetNumericValue();
tokenizer.ReadToken(",");
tokenizer.NextToken();
info.Ey = tokenizer.GetNumericValue();
tokenizer.ReadToken(",");
tokenizer.NextToken();
info.Ez = tokenizer.GetNumericValue();
tokenizer.NextToken();
if (tokenizer.GetStringValue() == ",")
{
tokenizer.NextToken();
info.Scale_ppm = tokenizer.GetNumericValue();
}
}
if (tokenizer.GetStringValue() != "]")
{
tokenizer.ReadToken("]");
}
return(info);
}
/// <summary>
/// 读取 HorizontalDatum
/// </summary>
/// <param name="tokenizer"></param>
/// <returns></returns>
private static HorizontalDatum ReadHorizontalDatum(WktStreamTokenizer tokenizer)
{
//DATUM["OSGB 1936",SPHEROID["Airy 1830",6377563.396,299.3249646,AUTHORITY["EPSG","7001"]],TOWGS84[0,0,0,0,0,0,0],AUTHORITY["EPSG","6277"]]
BursaTransParams wgsInfo = null;
string authority = String.Empty;
long authorityCode = -1;
tokenizer.ReadToken("[");
string name = tokenizer.ReadDoubleQuotedWord();
tokenizer.ReadToken(",");
tokenizer.ReadToken("SPHEROID");
Ellipsoid ellipsoid = ReadEllipsoid(tokenizer);
tokenizer.NextToken();
while (tokenizer.GetStringValue() == ",")
{
tokenizer.NextToken();
if (tokenizer.GetStringValue() == "TOWGS84")
{
wgsInfo = ReadWGS84ConversionInfo(tokenizer);
tokenizer.NextToken();
}
else if (tokenizer.GetStringValue() == "AUTHORITY")
{
tokenizer.ReadAuthority(ref authority, ref authorityCode);
tokenizer.ReadToken("]");
}
}
// make an assumption about the datum type.
HorizontalDatum horizontalDatum = new HorizontalDatum(
ellipsoid,
wgsInfo,
DatumType.HD_Geocentric,
name,
authorityCode + "");
return(horizontalDatum);
}
/// <summary>
/// Creates <see cref="HorizontalDatum"/> from ellipsoid and Bursa-World parameters.
/// </summary>
/// <remarks>
/// Since this method contains a set of Bursa-Wolf parameters, the created
/// datum will always have a relationship to WGS84. If you wish to create a
/// horizontal datum that has no relationship with WGS84, then you can
/// either specify a <see cref="DatumType">horizontalDatumType</see> of <see cref="DatumType.HD_Other"/>, or create it via WKT.
/// </remarks>
/// <param name="name">Name of ellipsoid</param>
/// <param name="datumType">Type of datum</param>
/// <param name="ellipsoid">Ellipsoid</param>
/// <param name="toWgs84">Wgs84 conversion parameters</param>
/// <returns>Horizontal datum</returns>
public HorizontalDatum CreateHorizontalDatum(string name, DatumType datumType, Ellipsoid ellipsoid, BursaTransParams toWgs84)
{
if (string.IsNullOrEmpty(name))
{
throw new ArgumentException("Invalid name");
}
if (ellipsoid == null)
{
throw new ArgumentException("Ellipsoid was null");
}
return(new HorizontalDatum(ellipsoid, toWgs84, datumType, name));
}
