Validation.h

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/*  Copyright (C) 2008 National Institute For Space Research (INPE) - Brazil.
 
    This file is part of the TerraLib - a Framework for building GIS enabled applications.
 
    TerraLib 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 3 of the License,
    or (at your option) any later version.
 
    TerraLib 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 TerraLib. See COPYING. If not, write to
    TerraLib Team at <terralib-team@terralib.org>.
 */
 
/*!
  \file terralib/geometry/Validation.h
 
  \brief A list of Validation functions for the Geometry Module.
*/
 
#ifndef __TERRALIB_GEOMETRY_INTERNAL_VALIDATION_H
#define __TERRALIB_GEOMETRY_INTERNAL_VALIDATION_H
 
// TerraLib
#include "Config.h"
 
#include "Coord2D.h"
 
// STL
#include <map>
#include <string>
#include <vector>
 
namespace te
{
  namespace gm
  {
// Forward declarations
    class Geometry;
    class GeometryPtr;
    class LineString;
   
    /*!
    \struct TopologyValidationError
 
    \brief This struct contains informations about GEOS TopologyValidationError
    */
    struct TopologyValidationError
    {
      public:
 
        Coord2D     m_coordinate;
        std::string m_message;
    };
 
    class TEGEOMEXPORT Validation
    {
    public:
 
      /*!
        \brief It check geometry validity using GEOS.
 
        \param geom  Geometry that will be verified.
        \param error TopologyValidationError struct.
 
        \return True if geometry is valid.
      */
      static bool CheckValidity(const Geometry* geom, te::gm::TopologyValidationError& error);
 
      /*!
            \brief Get/create a valid version of the geometry given. If the geometry is a polygon or multi polygon, self intersections /
                   inconsistencies are fixed. Otherwise the geometry is returned.
 
            \param geom
            \return a geometry
 
            \note: https://stackoverflow.com/questions/31473553/is-there-a-way-to-convert-a-self-intersecting-polygon-to-a-multipolygon-in-jts
            */
      static te::gm::Geometry* Validate(te::gm::Geometry* geom);
 
      /*! Fixes the given geometry. It ensures that all the coordinates will be kept. This algorithm is very conservative. 
       * It handles very well polygons containing self intersections like the 8 (eight number) or infinite symbol
       * Important: This may result is some area addition in the cases in which the border of the polygon contains several self touching segments (in both directions) linkng the same area.
       * This situation is usually resulted froma difference operation executed without first snapping both geometries
       */
      static te::gm::GeometryPtr MakeValid(const te::gm::Geometry* geometry);
 
      /*! Fixes the given geometry. It ensures that all the coordinates will be kept. This algorithm is very conservative.
       * It handles very well polygons containing self intersections like the 8 (eight number) or infinite symbol
       * Important: This may result is some area addition in the cases in which the border of the polygon contains several self touching segments (in both directions) linkng the same area.
       * This situation is usually resulted froma difference operation executed without first snapping both geometries
       */
      static te::gm::GeometryPtr MakeValid(const te::gm::Geometry* geometry, std::string& errorMessage);
 
      /*! Snaps the vertices in the component geom::LineStrings of the source geometry to the vertices of itself with a given snap tolerance and optionally cleaning the result. By GEOS
       * Important: This function may discard the entire geometry and return null if it is not able to execute the operation.
       * It does not handle well polygons containing self intersections like the 8 (eight number) or infinite symbol
       * In this case, choose MakeValid
       */
      static te::gm::GeometryPtr SnapToSelf(const te::gm::Geometry* geometry, double tolerance, bool cleanResult);
 
      /*! Snaps the vertices in the component geom::LineStrings of the source geometry to the vertices of itself with a given snap tolerance and optionally cleaning the result. By GEOS
       * Important: This function may discard the entire geometry and return null if it is not able to execute the operation. 
       * It does not handle well polygons containing self intersections like the 8 (eight number) or infinite symbol
       * In this case, choose MakeValid
       */
      static te::gm::GeometryPtr SnapToSelf(const te::gm::Geometry* geometry);
 
      /*! Tries to fix a geometry in a better way by combining two algorithms: SnapToSelf and MakeValid
       * It fixes the geometry using the following steps: First try to apply the snapToSelf algorithm. 
       * If the result is empty or if the area of the resulting geometry has changed significantly, it assumes that the snapToSelf was not able to fix it appropriately.
       * In this case, it then applies the makeValid algorithm (that is more conservative) and returns the result.
       */
      static te::gm::GeometryPtr MakeValidWithSnap(const te::gm::Geometry* geometry);
 
    private:
 
      /*!
        \brief Apply several fixes to a geometry to ensure that it will be made valid. New implementations must call MakeValidGeos
 
        \description It applies the following fixes:
                     1 - Removes all the repeated consecutive coordidates
                     2 - Add perpendicular points that are within the tolerance to each analysed segment
                     3 - We snap the coordinates to ensure that any "similar" coordinate is now equal
                     4 - To avoid the discard of rings in geos polygonize function, we must ensure that we removed all the collapsed segments
                     5 - Finally we applies a polygonizer to recreate the geometry and ensure that it is now consistent
 
        \param geom  Geometry that will be verified.
 
        \return True if geometry is valid.
      */
      static te::gm::GeometryPtr MakeValidTerralib(const te::gm::Geometry* geometry, std::string& errorMessage);
 
      //!< Executes the makeValid from Geos
      static te::gm::GeometryPtr MakeValidGeos(const te::gm::Geometry* geometry, std::string& errorMessage);
 
 
      
    };
 
  } // end namespace gm
}   // end namespace te
 
#endif  // __TERRALIB_GEOMETRY_INTERNAL_VALIDATION_H