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com.supermap.data

Class GeoDatum

  • java.lang.Object
    • com.supermap.data.GeoDatum

  • public class GeoDatum
extends java.lang.Object

    The GeoDatum class.

    This class contains the earth spheroid parameters.

    The Earth Ellipsoid is only a simple description to the size and shape of the Earth. For more accurate description of the real position of objects on Earth, it is required to introduce the earth reference system which has decided the relative position between the earth spheroid and the centroid of the Earth to provide a frame for surveying the objects on the Earth and the origin and direction of surface Lat/Lon Grid. The earth reference system (Datum) thought the centre of ellipsoid as origin. The Earth Ellipsoid in a region's datum may offset the true center of the Earth more or less, but it is the best description to the surface of this region. The coordinates of all the objects in the surface are relative to this ellipsoid enter. Up to now, the general used datum is WGS84 which acts as the basic frame for Geodesy. Different datum is suited for different countries and regions. One Datum can not be applied to any regions.

    • Constructor Summary

      Constructors 
      Constructor and Description
      GeoDatum()
      Constructs a new GeoDatum object.
      GeoDatum(GeoDatum geoDatum)
      Constructs a new object identical to the given GeoDatum object.
      GeoDatum(GeoDatumType type)
      Creates a new GeoDatum object according to the specified arguments.
      GeoDatum(GeoSpheroid geoSpheroid, java.lang.String name)
      Creates a new GeoDatum object according to the specified arguments.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method and Description
      GeoDatum clone()
      Return a copy of the current GeoDatum object.
      void dispose()
      Disposes the resources occupied by the object.
      boolean fromXML(java.lang.String xml)
      Creates a GeoDatum object with the specified XML string.
      GeoSpheroid getGeoSpheroid()
      Returns the spheroid object of the datum.
      java.lang.String getName()
      Returns the name of the GeoDatum object.
      GeoDatumType getType()
      Returns the type of the GeoDatum object.
      void setGeoSpheroid(GeoSpheroid value)
      Sets the spheroid object of the datum.
      void setName(java.lang.String value)
      Sets the name of the GeoDatum.
      void setType(GeoDatumType value)
      Sets the type of the datum.
      java.lang.String toXML()
      Exports the XML string represents the GeoDatum object.

      • Methods inherited from class java.lang.Object

        equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • GeoDatum

        public GeoDatum()
        Constructs a new GeoDatum object.

      • GeoDatum

        public GeoDatum(GeoDatumType type)
        Creates a new GeoDatum object according to the specified arguments.
        Parameters:
        type - the GeoDatum type specified.

      • GeoDatum

        public GeoDatum(GeoSpheroid geoSpheroid,
                java.lang.String name)
        Creates a new GeoDatum object according to the specified arguments.
        Parameters:
        geoSpheroid - Earth Ellipsoid
        name - the name of the GeoDatum .

      • GeoDatum

        public GeoDatum(GeoDatum geoDatum)
        Constructs a new object identical to the given GeoDatum object.
        Parameters:
        geoDatum - The specified GeoDatum object.

    • Method Detail

      • getName

        public java.lang.String getName()
        Returns the name of the GeoDatum object.
        Returns:
        the name of the GeoDatum object.
        Default:
        the default value is "User Define".

      • setName

        public void setName(java.lang.String value)
        Sets the name of the GeoDatum.
        Parameters:
        value - the name of the GeoDatum object.

      • getGeoSpheroid

        public GeoSpheroid getGeoSpheroid()
        Returns the spheroid object of the datum. It is available when the type of datum is user-defined.

        Generally, the spheroid or ellipsoid is used to describe the Earth's shape and magnitude. For easier to calculate, the Earth can be regard as a spheroid but most times it is regard as an ellipsoid. In general, the Earth's shape is supposing to be a spheroid when the map scale is less than 1:1,000,000. Because under this circumstance, the difference of spheroid and ellipsoid is very small. But for the big scale greater 1:1,000,000, it is necessary to use ellipsoid to approach the Earth. The ellipsoid is based on ellipse, so using two axes to express the magnitude of the Earth, that is the major axis (radius of the equator) and the minor axis (radius of the polar).

        Returns:
        the earth spheroid object.
        Default:
        The default value is an empty GeoSpheroid object.

      • setGeoSpheroid

        public void setGeoSpheroid(GeoSpheroid value)
        Sets the spheroid object of the datum. It is available when the type of datum is user-defined.

        Generally, the spheroid or ellipsoid is used to describe the Earth's shape and magnitude. For easier to calculate, the Earth can be regard as a spheroid but most times it is regard as an ellipsoid. In general, the Earth's shape is supposing to be a spheroid when the map scale is less than 1:1,000,000. Because under this circumstance, the difference of spheroid and ellipsoid is very small. But for the big scale greater 1:1,000,000, it is necessary to use ellipsoid to approach the Earth. The ellipsoid is based on ellipse, so using two axes to express the magnitude of the Earth, that is the major axis (radius of the equator) and the minor axis (radius of the polar).

        Parameters:
        value - The earth spheroid object.

      • getType

        public GeoDatumType getType()
        Returns the type of the GeoDatum object.

        When the datum is defined by the user, it is required to specify ellipsoid parameters; other values are predefined by SuperMap Objects Java. Refer to GeoDatumType.

        Returns:
        the type of the GeoDatum object.
        Default:
        The default value is DATUM_WGS_1984.

      • setType

        public void setType(GeoDatumType value)
        Sets the type of the datum.

        When the datum is defined by the user, it is required to specify ellipsoid parameters; other values are predefined by SuperMap Objects Java. Refer to GeoDatumType.

        Parameters:
        value - the type of the GeoDatum object.

      • clone

        public GeoDatum clone()
        Return a copy of the current GeoDatum object.
        Overrides:
        clone in class java.lang.Object
        Returns:
        The new GeoDatum object generated from the clone operation.

      • fromXML

        public boolean fromXML(java.lang.String xml)
        Creates a GeoDatum object with the specified XML string.
        Parameters:
        xml - The specified XML string.
        Returns:
        Returns true, if successful; otherwise, false.

      • toXML

        public java.lang.String toXML()
        Exports the XML string represents the GeoDatum object.
        Returns:
        the XML string represents the GeoDatum object.

      • dispose

        public void dispose()
        Disposes the resources occupied by the object. After calling this method, this object will not be usable.
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