icoordinatesystem.cs

Sharp Map 用于制作GIS系统S harp Map 用于制作GIS系统S harp Map 用于制作GIS系统

// Copyright 2005, 2006 - Morten Nielsen (www.iter.dk)
//
// This file is part of SharpMap.
// SharpMap is free software; you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
// 
// SharpMap is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Lesser General Public License for more details.

// You should have received a copy of the GNU Lesser General Public License
// along with SharpMap; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 

using System;
using System.Collections.Generic;
using System.Text;

namespace SharpMap.CoordinateSystems
{
	/// <summary>
	/// Base interface for all coordinate systems
	/// </summary>
	/// <remarks>
	/// <para>A coordinate system is a mathematical space, where the elements of the space are called
	/// positions. Each position is described by a list of numbers. The length of the list corresponds
	/// to the dimension of the coordinate system. So in a 2D coordinate system each position is 
	/// described by a list containing 2 numbers.</para>
	/// <para>
	/// However, in a coordinate system, not all lists of numbers correspond to a position - 
	/// some lists may be outside the domain of the coordinate system. For example, in a 2D Lat/Lon
	/// coordinate system, the list (91,91) does not correspond to a position.</para>
	/// <para>
	/// Some coordinate systems also have a mapping from the mathematical space into locations
	/// in the real world. So in a Lat/Lon coordinate system, the mathematical position (lat, long) 
	/// corresponds to a location on the surface of the Earth. This mapping from the mathematical 
	/// space into real-world locations is called a Datum.</para>
	/// </remarks>
	public interface ICoordinateSystem : IInfo {
		/// <summary>
		/// Dimension of the coordinate system.
		/// </summary>
		int Dimension { get; }

		/// <summary>
		/// Gets axis details for dimension within coordinate system.
		/// </summary>
		/// <param name="dimension">Dimension</param>
		/// <returns>Axis info</returns>
		AxisInfo GetAxis(int dimension);
		/// <summary>
		/// Gets units for dimension within coordinate system.
		/// </summary>
		IUnit GetUnits(int dimension);
		/// <summary>
		/// Gets default envelope of coordinate system.
		/// </summary>
		/// <remarks>
		/// Gets default envelope of coordinate system. Coordinate systems 
		/// which are bounded should return the minimum bounding box of their 
		/// domain. Unbounded coordinate systems should return a box which is 
		/// as large as is likely to be used. For example, a (lon,lat) 
		/// geographic coordinate system in degrees should return a box from 
		/// (-180,-90) to (180,90), and a geocentric coordinate system could 
		/// return a box from (-r,-r,-r) to (+r,+r,+r) where r is the 
		/// approximate radius of the Earth.
		/// </remarks>
		SharpMap.Geometries.BoundingBox DefaultEnvelope { get; }
	}
}