
///////////////////////////////////////////////////////////
//                                                       //
//                         SAGA                          //
//                                                       //
//      System for Automated Geoscientific Analyses      //
//                                                       //
//                     Tool Library                      //
//                       Tutorial                        //
//                                                       //
//-------------------------------------------------------//
//                                                       //
//                    Grid_Merge.cpp                     //
//                                                       //
//                 Copyright (C) 2003 by                 //
//                      Olaf Conrad                      //
//                                                       //
//-------------------------------------------------------//
//                                                       //
// This file is part of 'SAGA - System for Automated     //
// Geoscientific Analyses'. SAGA is free software; you   //
// can redistribute it and/or modify it under the terms  //
// of the GNU General Public License as published by the //
// Free Software Foundation, either version 2 of the     //
// License, or (at your option) any later version.       //
//                                                       //
// SAGA 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 General Public        //
// License for more details.                             //
//                                                       //
// You should have received a copy of the GNU General    //
// Public License along with this program; if not, see   //
// <http://www.gnu.org/licenses/>.                       //
//                                                       //
//-------------------------------------------------------//
//                                                       //
//    e-mail:     oconrad@saga-gis.org                   //
//                                                       //
//    contact:    Olaf Conrad                            //
//                Institute of Geography                 //
//                University of Goettingen               //
//                Goldschmidtstr. 5                      //
//                37077 Goettingen                       //
//                Germany                                //
//                                                       //
///////////////////////////////////////////////////////////

//---------------------------------------------------------
#include "Grid_Merge.h"


///////////////////////////////////////////////////////////
//														 //
//														 //
//														 //
///////////////////////////////////////////////////////////

//---------------------------------------------------------
CGrid_Merge::CGrid_Merge(void)
{
	Set_Name		(_TL("Mosaicking"));

	Set_Author		("O.Conrad (c) 2003-17");

	Set_Description	(_TW(
		"The tool allows one to merge multiple grids into one single grid. This "
		"involves resampling if the input grids have different cell sizes or are "
		"not aligned to each other. Besides different resampling methods, the tool "
		"provides several options on how to handle overlapping areas. It is also "
		"possible to apply a histogram matching. "
		"\n\n"
		"In order to be able to also merge a large amount of grids, which, for "
		"example, would exceed the maximum command line length, the tools has "
		"the option to provide a file list as input (instead of using the input "
		"grid list). This is a text file with the full path to an input grid "
		"on each line. Please note the limitations: (i) the target grid system "
		"is set automatically in this case (the extent is calculated from all "
		"inputs and the cell size is set to the smallest one detected) and (ii) "
		"the input grids must still fit into memory, i.e. are all loaded at once.\n\n"
	));

	//-----------------------------------------------------
	Parameters.Add_Grid_List("",
		"GRIDS"		, _TL("Grids"),
		_TL(""),
		PARAMETER_INPUT_OPTIONAL
	);

	Parameters.Add_FilePath("",
		"FILE_LIST"	, _TL("Input File List"),
		_TL("A text file with the full path to an input grid on each line"),
		CSG_String::Format("%s|*.txt|%s|*.*",
			_TL("Text Files"),
            _TL("All Files")
        ), NULL, false, false, false
	)->Set_UseInGUI(false);

	Add_Parameters(Parameters);

	//-----------------------------------------------------
	m_Grid_Target.Create(&Parameters, true, "", "TARGET_");
};

//---------------------------------------------------------
void CGrid_Merge::Add_Parameters(CSG_Parameters &Parameters)
{
	Parameters.Add_String("",
		"NAME"		, _TL("Name"),
		_TL(""),
		_TL("Mosaic")
	)->Set_UseInCMD(false);

	Parameters.Add_Data_Type("",
		"TYPE"		, _TL("Data Storage Type"),
		_TL(""),
		SG_DATATYPES_Numeric|SG_DATATYPES_Bit, SG_DATATYPE_Undefined, _TL("same as first grid in list")
	);

	Parameters.Add_Choice("",
		"RESAMPLING", _TL("Resampling"),
		_TL(""),
		CSG_String::Format("%s|%s|%s|%s",
			_TL("Nearest Neighbour"           ),
			_TL("Bilinear Interpolation"      ),
			_TL("Bicubic Spline Interpolation"),
			_TL("B-Spline Interpolation"      )
		), 3
	);

	Parameters.Add_Choice("",
		"OVERLAP"	, _TL("Overlapping Areas"),
		_TL(""),
		CSG_String::Format("%s|%s|%s|%s|%s|%s|%s",
			_TL("first"         ),
			_TL("last"          ),
			_TL("minimum"       ),
			_TL("maximum"       ),
			_TL("mean"          ),
			_TL("blend boundary"),
			_TL("feathering"    )
		), 1
	);

	Parameters.Add_Double("",
		"BLEND_DIST", _TL("Blending Distance"),
		_TL("blending distance given in map units"),
		10.0, 0.0, true
	);

	Parameters.Add_Choice("",
		"BLEND_BND"	, _TL("Blending Boundary"),
		_TL("blending boundary for distance calculation"),
		CSG_String::Format("%s|%s|%s|%s",
			_TL("valid data cells"          ),
			_TL("grid boundaries"           ),
			_TL("vertical grid boundaries"  ),
			_TL("horizontal grid boundaries")
		), 0
	);

	Parameters.Add_Choice("",
		"MATCH"		, _TL("Match"),
		_TL(""),
		CSG_String::Format("%s|%s|%s|%s",
			_TL("none"                                 ),
			_TL("match histogram of first grid in list"),
			_TL("match histogram of overlapping area"  ),
			_TL("regression"                           )
		), 0
	);
}


///////////////////////////////////////////////////////////
//														 //
///////////////////////////////////////////////////////////

//---------------------------------------------------------
int CGrid_Merge::On_Parameter_Changed(CSG_Parameters *pParameters, CSG_Parameter *pParameter)
{
	if( pParameter->Cmp_Identifier("GRIDS") )
	{
		Set_Target(pParameters, pParameter->asList(), m_Grid_Target);
	}

	m_Grid_Target.On_Parameter_Changed(pParameters, pParameter);

	return( CSG_Tool::On_Parameter_Changed(pParameters, pParameter) );
}

//---------------------------------------------------------
int CGrid_Merge::On_Parameters_Enable(CSG_Parameters *pParameters, CSG_Parameter *pParameter)
{
	if(	pParameter->Cmp_Identifier("GRIDS") )
	{
		pParameters->Set_Enabled("FILE_LIST" , pParameter->asGridList()->Get_Grid_Count() < 1);
	}

	if(	pParameter->Cmp_Identifier("OVERLAP") )
	{
		pParameters->Set_Enabled("BLEND_DIST", pParameter->asInt() == 5 || pParameter->asInt() == 6);
		pParameters->Set_Enabled("BLEND_BND" , pParameter->asInt() == 5 || pParameter->asInt() == 6);
	}

	m_Grid_Target.On_Parameters_Enable(pParameters, pParameter);

	return( CSG_Tool::On_Parameters_Enable(pParameters, pParameter) );
}


///////////////////////////////////////////////////////////
//														 //
///////////////////////////////////////////////////////////

//---------------------------------------------------------
bool CGrid_Merge::On_Execute(void)
{
	if( !Initialize() )
	{
		return( false );
	}

	//-----------------------------------------------------
	for(int i=0; i<m_pGrids->Get_Grid_Count(); i++)
	{
		CSG_Grid *pGrid = m_pGrids->Get_Grid(i);

		Set_Weight(pGrid);

		Get_Match(i > 0 ? pGrid : NULL);

		int ax = (int)((pGrid->Get_XMin() - m_pMosaic->Get_XMin()) / m_pMosaic->Get_Cellsize());
		int ay = (int)((pGrid->Get_YMin() - m_pMosaic->Get_YMin()) / m_pMosaic->Get_Cellsize());

		//-------------------------------------------------
		if(	is_Aligned(pGrid) )
		{
			Process_Set_Text("[%d/%d] %s: %s", i + 1, m_pGrids->Get_Grid_Count(), _TL("copying"), pGrid->Get_Name());

			int nx = pGrid->Get_NX(); if( nx > m_pMosaic->Get_NX() - ax ) nx = m_pMosaic->Get_NX() - ax;
			int ny = pGrid->Get_NY(); if( ny > m_pMosaic->Get_NY() - ay ) ny = m_pMosaic->Get_NY() - ay;

			for(int y=0; y<ny && Set_Progress(y, ny); y++)
			{
				if( ay + y >= 0 )
				{
					#pragma omp parallel for
					for(int x=0; x<nx; x++)
					{
						if( ax + x >= 0 && !pGrid->is_NoData(x, y) )
						{
							Set_Value(ax + x, ay + y, pGrid->asDouble(x, y), Get_Weight(x, y));
						}
					}
				}
			}
		}

		//-------------------------------------------------
		else
		{
			Process_Set_Text("[%d/%d] %s: %s", i + 1, m_pGrids->Get_Grid_Count(), _TL("resampling"), pGrid->Get_Name());

			if( ax < 0 ) ax = 0;
			if( ay < 0 ) ay = 0;

			int nx = 1 + m_pMosaic->Get_System().Get_xWorld_to_Grid(pGrid->Get_XMax()); if( nx > m_pMosaic->Get_NX() ) nx = m_pMosaic->Get_NX();
			int ny = 1 + m_pMosaic->Get_System().Get_yWorld_to_Grid(pGrid->Get_YMax()); if( ny > m_pMosaic->Get_NY() ) ny = m_pMosaic->Get_NY();

			for(int y=ay; y<ny && Set_Progress(y-ay, ny-ay); y++)
			{
				double py = m_pMosaic->Get_YMin() + y * m_pMosaic->Get_Cellsize();

				#pragma omp parallel for
				for(int x=ax; x<nx; x++)
				{
					double px = m_pMosaic->Get_XMin() + x * m_pMosaic->Get_Cellsize();

					Set_Value(x, y, pGrid, px, py);
				}
			}
		}
	}

	//-----------------------------------------------------
	if( m_Overlap == 4 )	// mean
	{
		for(int y=0; y<m_pMosaic->Get_NY() && Set_Progress(y, m_pMosaic->Get_NY()); y++)
		{
			#pragma omp parallel for
			for(int x=0; x<m_pMosaic->Get_NX(); x++)
			{
				double w = m_Weights.asDouble(x, y);

				if( w > 0. )
				{
					m_pMosaic->Mul_Value(x, y, 1.0 / w);
				}
			}
		}
	}

	//-----------------------------------------------------
	m_Weight .Destroy();
	m_Weights.Destroy();

	if( m_bFileList )
	{
		for(int i=0; i<m_pGrids->Get_Grid_Count(); i++)
		{
			delete(m_pGrids->Get_Grid(i));
		}

		m_pGrids->Del_Items();
	}

	return( true );
}


///////////////////////////////////////////////////////////
//														 //
///////////////////////////////////////////////////////////

//---------------------------------------------------------
bool CGrid_Merge::Initialize(void)
{
	m_pMosaic	= NULL;

	m_Overlap	= Parameters("OVERLAP"   )->asInt();
	m_pGrids	= Parameters("GRIDS"     )->asGridList();
	m_dBlend	= Parameters("BLEND_DIST")->asDouble();

	//-----------------------------------------------------
	if( m_pGrids->Get_Grid_Count() < 1 )
	{
		SG_UI_Msg_Add(_TL("input grid list is empty, trying to open input file list."), true);

		CSG_Table	Table;

		if( !Table.Create(Parameters("FILE_LIST")->asString(), TABLE_FILETYPE_Text_NoHeadLine) )
		{
			Error_Set(_TL("input file list could not be opened or is empty!"));

			return( false );
		}

		for(sLong i=0; i<Table.Get_Count(); i++)
		{
			m_pGrids->Add_Item(SG_Create_Grid(Table[i].asString(0)));
		}

		Set_Target(&Parameters, m_pGrids, m_Grid_Target);

		m_bFileList	= true;
	}
	else
	{
		m_bFileList	= false;
	}
	
	//-----------------------------------------------------
	switch( Parameters("RESAMPLING")->asInt() )
	{
	default: m_Resampling = GRID_RESAMPLING_NearestNeighbour; break;
	case  1: m_Resampling = GRID_RESAMPLING_Bilinear        ; break;
	case  2: m_Resampling = GRID_RESAMPLING_BicubicSpline   ; break;
	case  3: m_Resampling = GRID_RESAMPLING_BSpline         ; break;
	}

	//-----------------------------------------------------
	TSG_Data_Type Type = Parameters("TYPE")->asDataType()->Get_Data_Type(m_pGrids->Get_Grid(0)->Get_Type());

	if( (m_pMosaic = m_Grid_Target.Get_Grid(Type)) == NULL )
	{
		return( false );
	}

	if( m_pMosaic->Get_Type() != Type )
	{
		if( !m_pMosaic->Create(m_pMosaic->Get_System(), Type) )
		{
			return( false );
		}
	}

	if( Parameters("TYPE")->asDataType()->Get_Data_Type() == SG_DATATYPE_Undefined ) // same as first grid in list
	{
		m_pMosaic->Set_Scaling(
			m_pGrids->Get_Grid(0)->Get_Scaling(),
			m_pGrids->Get_Grid(0)->Get_Offset ()
		);
	}

	//-----------------------------------------------------
	if( has_GUI() )
	{
		m_pMosaic->Set_Name(Parameters("NAME")->asString());
	}

	m_pMosaic->Assign_NoData();

	//-----------------------------------------------------
	switch( m_Overlap )
	{
	case 4:	// mean
		if( !m_Weights.Create(m_pMosaic->Get_System(), m_pGrids->Get_Grid_Count() < 256 ? SG_DATATYPE_Byte : SG_DATATYPE_Word) )
		{
			Error_Set(_TL("could not create weights grid"));

			return( false );
		}

		break;

	case 6:	// feathering
		if( !m_Weights.Create(m_pMosaic->Get_System(), SG_DATATYPE_Word) )
		{
			Error_Set(_TL("could not create weights grid"));

			return( false );
		}

		m_Weights.Set_Scaling(m_pMosaic->Get_Cellsize());

		break;
	}

	return( true );
}


///////////////////////////////////////////////////////////
//														 //
///////////////////////////////////////////////////////////

//---------------------------------------------------------
void CGrid_Merge::Set_Target(CSG_Parameters *pParameters, CSG_Parameter_List *pList, CSG_Parameters_Grid_Target &Target)
{
	if( !pParameters || !pList || pList->Get_Item_Count() < 1 )
	{
		return;
	}

	#define GET_SYSTEM(i)	(pList->Get_Type() == PARAMETER_TYPE_Grids_List\
		? ((CSG_Grids *)pList->Get_Item(i))->Get_System()\
		: ((CSG_Grid  *)pList->Get_Item(i))->Get_System())

	CSG_Grid_System	System(GET_SYSTEM(0));
	
	double		d	= System.Get_Cellsize();
	CSG_Rect	r	= System.Get_Extent();

	for(int i=1; i<pList->Get_Item_Count(); i++)
	{
		System	= GET_SYSTEM(i);

		if( d > System.Get_Cellsize() )
		{
			d	= System.Get_Cellsize();
		}

		r.Union(System.Get_Extent());
	}

	int	nx	= 1 + (int)(r.Get_XRange() / d);
	int	ny	= 1 + (int)(r.Get_YRange() / d);

	Target.Set_User_Defined(pParameters, r.Get_XMin(), r.Get_YMin(), d, nx, ny);
}


///////////////////////////////////////////////////////////
//														 //
///////////////////////////////////////////////////////////

//---------------------------------------------------------
bool CGrid_Merge::is_Aligned(CSG_Grid *pGrid)
{
	return(	pGrid->Get_Cellsize() == m_pMosaic->Get_Cellsize()
		&&	fabs(fmod(pGrid->Get_XMin() - m_pMosaic->Get_XMin(), m_pMosaic->Get_Cellsize())) <= 0.001 * m_pMosaic->Get_Cellsize()
		&&	fabs(fmod(pGrid->Get_YMin() - m_pMosaic->Get_YMin(), m_pMosaic->Get_Cellsize())) <= 0.001 * m_pMosaic->Get_Cellsize()
	);
}

//---------------------------------------------------------
inline void CGrid_Merge::Set_Value(int x, int y, double Value, double Weight)
{
	if( m_Match.Get_N() == 2 )		// regression
	{
		Value	= m_Match[0] + m_Match[1] * Value;
	}
	else if( m_Match.Get_N() == 3 )	// standardization
	{
		Value	= m_Match[0] + m_Match[1] * (Value - m_Match[2]);
	}

	switch( m_Overlap )
	{
	case 0:	// first
		if( m_pMosaic->is_NoData(x, y) )
		{
			m_pMosaic->Set_Value(x, y, Value);
		}
		break;

	case 1:	// last
		{
			m_pMosaic->Set_Value(x, y, Value);
		}
		break;

	case 2:	// minimum
		if( m_pMosaic->is_NoData(x, y) || m_pMosaic->asDouble(x, y) > Value )
		{
			m_pMosaic->Set_Value(x, y, Value);
		}
		break;

	case 3:	// maximum
		if( m_pMosaic->is_NoData(x, y) || m_pMosaic->asDouble(x, y) < Value )
		{
			m_pMosaic->Set_Value(x, y, Value);
		}
		break;

	case 4:	// mean
		if( m_pMosaic->is_NoData(x, y) )
		{
			m_pMosaic->Set_Value(x, y, Value);
			m_Weights .Set_Value(x, y, 1);
		}
		else
		{
			m_pMosaic->Add_Value(x, y, Value);
			m_Weights .Add_Value(x, y, 1);
		}
		break;

	case 5:	// blend
		if( m_pMosaic->is_NoData(x, y) )
		{
			m_pMosaic->Set_Value(x, y, Value);
		}
		else
		{
			m_pMosaic->Set_Value(x, y, (1.0 - Weight) * m_pMosaic->asDouble(x, y) + Weight * Value);
		}
		break;

	case 6:	// feathering
		if( m_pMosaic->is_NoData(x, y) )
		{
			m_pMosaic->Set_Value(x, y, Value);
			m_Weights .Set_Value(x, y, Weight);
		}
		else
		{
			double	d	= (Weight - m_Weights.asDouble(x, y)) / m_dBlend;

			if( d >= 1.0 )
			{
				m_pMosaic->Set_Value(x, y, Value);
				m_Weights .Set_Value(x, y, Weight);
			}
			else if( d > -1.0 )
			{
				d	= 0.5 * (1.0 + d);

				m_pMosaic->Set_Value(x, y, (1.0 - d) * m_pMosaic->asDouble(x, y) + d * Value);

				if( d > 0.5 )
				{
					m_Weights .Set_Value(x, y, Weight);
				}
			}
		}
		break;
	}
}

//---------------------------------------------------------
inline void CGrid_Merge::Set_Value(int x, int y, CSG_Grid *pGrid, double px, double py)
{
	double	z;

	if( pGrid->Get_Value(px, py, z, m_Resampling) )
	{
		if( m_Weight.is_Valid() )
		{
			double	w;

			if( m_Weight.Get_Value(px, py, w) )
			{
				Set_Value(x, y, z, w);
			}
		}
		else
		{
			Set_Value(x, y, z, 1.0);
		}
	}
}


///////////////////////////////////////////////////////////
//														 //
///////////////////////////////////////////////////////////

//---------------------------------------------------------
inline double CGrid_Merge::Get_Weight(int x, int y)
{
	return( m_Weight.is_Valid() ? m_Weight.asDouble(x, y) : 1.0 );
}

//---------------------------------------------------------
bool CGrid_Merge::Set_Weight(CSG_Grid *pGrid)
{
	int	dBlend;

	switch( m_Overlap )
	{
	default:	// only feathering/blending
		return( true );

	case 5:		// blending
		dBlend	= 1 + (int)(m_dBlend / pGrid->Get_Cellsize());
		break;

	case 6:		// feathering
		dBlend	= 0;
		break;
	}

	//-----------------------------------------------------
	if( !m_Weight.Get_System().is_Equal(pGrid->Get_System()) )
	{
		if( !m_Weight.Create(pGrid->Get_System(), dBlend > 0 && dBlend < 255 ? SG_DATATYPE_Byte : SG_DATATYPE_Word) )
		{
			Error_Set(_TL("could not create distance grid"));

			return( false );
		}
	}

	switch( Parameters("BLEND_BND")->asInt() )
	{
	//-----------------------------------------------------------
	case  1: {	// grid boundaries
		for(int iy=0, jy=pGrid->Get_NY()-1; iy<=jy; iy++, jy--)
		{
			for(int ix=0, jx=pGrid->Get_NX()-1; ix<=jx; ix++, jx--)
			{
				int	d	= 1 + (ix < iy ? ix : iy);	if( dBlend > 0 && d > dBlend )	{	d = dBlend;	}

				m_Weight.Set_Value(ix, iy, d);
				m_Weight.Set_Value(ix, jy, d);
				m_Weight.Set_Value(jx, iy, d);
				m_Weight.Set_Value(jx, jy, d);
			}
		}
	} break;

	//-----------------------------------------------------------
	case  2: {	// vertical grid boundaries
		for(int ix=0, jx=pGrid->Get_NX()-1; ix<=jx; ix++, jx--)
		{
			int	d	= 1 + ix;	if( dBlend > 0 && d > dBlend )	{	d = dBlend;	}

			for(int y=0; y<pGrid->Get_NY(); y++)
			{
				m_Weight.Set_Value(ix, y, d);
				m_Weight.Set_Value(jx, y, d);
			}
		}
	} break;

	//-----------------------------------------------------------
	case  3: {	// horizontal grid boundaries
		for(int iy=0, jy=pGrid->Get_NY()-1; iy<=jy; iy++, jy--)
		{
			int	d	= 1 + iy;	if( dBlend > 0 && d > dBlend )	{	d = dBlend;	}

			for(int x=0; x<pGrid->Get_NX(); x++)
			{
				m_Weight.Set_Value(x, iy, d);
				m_Weight.Set_Value(x, jy, d);
			}
		}
	} break;

	//-----------------------------------------------------------
	default: {	// valid data cells
		int		x, y, d;

		for(y=0; y<pGrid->Get_NY(); y++)
		{
			for(x=0, d=1; x<pGrid->Get_NX(); x++)
			{
				if( pGrid->is_NoData(x, y) )
					m_Weight.Set_Value(x, y, d = 0);
				else //if( m_Weight.asInt(x, y) > d )
					m_Weight.Set_Value(x, y, d);

				if( dBlend <= 0 || d < dBlend )	d++;
			}

			for(x=pGrid->Get_NX()-1, d=1; x>=0; x--)
			{
				if( pGrid->is_NoData(x, y) )
					m_Weight.Set_Value(x, y, d = 0);
				else if( m_Weight.asInt(x, y) > d )
					m_Weight.Set_Value(x, y, d);
				else
					d	= m_Weight.asInt(x, y);

				if( dBlend <= 0 || d < dBlend )	d++;
			}
		}

		for(x=0; x<pGrid->Get_NX(); x++)
		{
			for(y=0, d=1; y<pGrid->Get_NY(); y++)
			{
				if( pGrid->is_NoData(x, y) )
					m_Weight.Set_Value(x, y, d = 0);
				else if( m_Weight.asInt(x, y) > d )
					m_Weight.Set_Value(x, y, d);
				else
					d	= m_Weight.asInt(x, y);

				if( dBlend <= 0 || d < dBlend )	d++;
			}

			for(y=pGrid->Get_NY()-1, d=1; y>=0; y--)
			{
				if( pGrid->is_NoData(x, y) )
					m_Weight.Set_Value(x, y, d = 0);
				else if( m_Weight.asInt(x, y) > d )
					m_Weight.Set_Value(x, y, d);
				else
					d	= m_Weight.asInt(x, y);

				if( dBlend <= 0 || d < dBlend )	d++;
			}
		}
	} break;
	}

	//-----------------------------------------------------
	switch( m_Overlap )
	{
	case 5:	// blending
		m_Weight.Set_Scaling(1.0 / dBlend);	// normalize (0 <= z <= 1)
		break;

	case 6:	// feathering
		m_Weight.Set_Scaling(m_Weight.Get_Cellsize());
		break;
	}

	//-----------------------------------------------------
	return( true );
}


///////////////////////////////////////////////////////////
//														 //
///////////////////////////////////////////////////////////

//---------------------------------------------------------
void CGrid_Merge::Get_Match(CSG_Grid *pGrid)
{
	if( pGrid && Parameters("MATCH")->asInt() != 0 )
	{
		//-------------------------------------------------
		if( Parameters("MATCH")->asInt() == 1 )	// match histogram of first grid in list
		{
			m_Match.Create(3);

			m_Match[0]	= m_pGrids->Get_Grid(0)->Get_Mean();
			m_Match[2]	= pGrid->Get_Mean();
			m_Match[1]	= pGrid->Get_StdDev() ? m_pGrids->Get_Grid(0)->Get_StdDev() / pGrid->Get_StdDev() : 0.0;

			return;
		}

		//-------------------------------------------------
		else	// investigate overlapping areas
		{
			Process_Set_Text("%s: %s", _TL("analyzing overlap"), pGrid->Get_Name());

			int	ax	= (int)((pGrid->Get_XMin() - m_pMosaic->Get_XMin()) / m_pMosaic->Get_Cellsize());	if( ax < 0 )	ax	= 0;
			int	ay	= (int)((pGrid->Get_YMin() - m_pMosaic->Get_YMin()) / m_pMosaic->Get_Cellsize());	if( ay < 0 )	ay	= 0;

			int	nx	= 1 + m_pMosaic->Get_System().Get_xWorld_to_Grid(pGrid->Get_XMax()); if( nx > m_pMosaic->Get_NX() )	nx	= m_pMosaic->Get_NX();
			int	ny	= 1 + m_pMosaic->Get_System().Get_yWorld_to_Grid(pGrid->Get_YMax()); if( ny > m_pMosaic->Get_NY() )	ny	= m_pMosaic->Get_NY();

			CSG_Vector	Z[2];

			for(int y=ay; y<ny && Set_Progress(y-ay, ny-ay); y++)
			{
				double	py	= m_pMosaic->Get_YMin() + y * m_pMosaic->Get_Cellsize();

				for(int x=ax; x<nx; x++)
				{
					if( !m_pMosaic->is_NoData(x, y) )
					{
						double	z, px	= m_pMosaic->Get_XMin() + x * m_pMosaic->Get_Cellsize();

						if( pGrid->Get_Value(px, py, z, GRID_RESAMPLING_NearestNeighbour) )
						{
							Z[0].Add_Row(z);
							Z[1].Add_Row(m_pMosaic->asDouble(x, y));
						}
					}
				}
			}

			//---------------------------------------------
			if( Parameters("MATCH")->asInt() == 2 )	// match histogram of overlapping area
			{
				CSG_Simple_Statistics	S0(Z[0]), S1(Z[1]);

				m_Match.Create(3);

				m_Match[0]	= S1.Get_Mean();
				m_Match[2]	= S0.Get_Mean();
				m_Match[1]	= S0.Get_StdDev() ? S1.Get_StdDev() / S0.Get_StdDev() : 0.0;

				return;
			}

			//---------------------------------------------
			else	// regression
			{
				CSG_Regression	r;

				if( r.Calculate((int)Z[0].Get_Size(), Z[0].Get_Data(), Z[1].Get_Data()) )
				{
					m_Match.Create(2);

					m_Match[0]	= r.Get_Constant();
					m_Match[1]	= r.Get_Coefficient();

					Message_Add("histogram stretch:\n", false);
					Message_Add(r.asString(), false);

					return;
				}
			}
		}
	}

	//-----------------------------------------------------
	m_Match.Destroy();
}


///////////////////////////////////////////////////////////
//														 //
//														 //
//														 //
///////////////////////////////////////////////////////////

//---------------------------------------------------------
CGrids_Merge::CGrids_Merge(void)
{
	Set_Name		(_TL("Mosaicking (Grid Collections)"));

	Set_Author		("O.Conrad (c) 2017");

	Set_Description	(_TW(
		"Merges multiple grid collections into one single grid collection. "
		"Input grid collections have to share the same number of grid levels. "
		"Attributes and other general properties will be inherited from the "
		"first grid collection in input list. "
	));

	//-----------------------------------------------------
	Parameters.Add_Grids_List("",
		"GRIDS"		, _TL("Grid Collections"),
		_TL(""),
		PARAMETER_INPUT
	);

	CGrid_Merge::Add_Parameters(Parameters);

	//-----------------------------------------------------
	m_Grid_Target.Create(&Parameters, false, "", "TARGET_");

	m_Grid_Target.Add_Grids("MOSAIC", _TL("Mosaic"), false);
}


///////////////////////////////////////////////////////////
//														 //
///////////////////////////////////////////////////////////

//---------------------------------------------------------
int CGrids_Merge::On_Parameter_Changed(CSG_Parameters *pParameters, CSG_Parameter *pParameter)
{
	if( pParameter->Cmp_Identifier("GRIDS") )
	{
		CGrid_Merge::Set_Target(pParameters, pParameter->asList(), m_Grid_Target);
	}

	m_Grid_Target.On_Parameter_Changed(pParameters, pParameter);

	return( CSG_Tool::On_Parameter_Changed(pParameters, pParameter) );
}

//---------------------------------------------------------
int CGrids_Merge::On_Parameters_Enable(CSG_Parameters *pParameters, CSG_Parameter *pParameter)
{
	if(	pParameter->Cmp_Identifier("OVERLAP") )
	{
		pParameters->Set_Enabled("BLEND_DIST", pParameter->asInt() == 5 || pParameter->asInt() == 6);
		pParameters->Set_Enabled("BLEND_BND" , pParameter->asInt() == 5 || pParameter->asInt() == 6);
	}

	m_Grid_Target.On_Parameters_Enable(pParameters, pParameter);

	return( CSG_Tool::On_Parameters_Enable(pParameters, pParameter) );
}


///////////////////////////////////////////////////////////
//														 //
///////////////////////////////////////////////////////////

//---------------------------------------------------------
bool CGrids_Merge::On_Execute(void)
{
	CSG_Parameter_Grids_List *pList_Grids = Parameters("GRIDS")->asGridsList();

	if( pList_Grids->Get_Item_Count() < 1 )
	{
		Error_Set(_TL("nothing to do, input list is empty."));

		return( false );
	}

	//-----------------------------------------------------
	CSG_Grids  *pGrids = pList_Grids->Get_Grids(0);

	TSG_Data_Type Type = Parameters("TYPE")->asDataType()->Get_Data_Type(pGrids->Get_Type());

	CSG_Grids *pMosaic = m_Grid_Target.Get_Grids("MOSAIC");

	if( !pMosaic || !pMosaic->Create(CSG_Grid_System(pMosaic->Get_System()), pGrids->Get_Attributes(), pGrids->Get_Z_Attribute(), Type, true) )
	{
		Error_Set(_TL("failed to allocate memory for target data."));

		return( false );
	}

	pMosaic->Set_NoData_Value_Range(pGrids->Get_NoData_Value(), pGrids->Get_NoData_Value(true));
	pMosaic->Set_Scaling(pGrids->Get_Scaling(), pGrids->Get_Offset());
	pMosaic->Set_Z_Name_Field(pGrids->Get_Z_Name_Field());

	//-----------------------------------------------------
	CGrid_Merge	Mosaic;

	Mosaic.Set_Manager(NULL);
	Mosaic.Get_Parameters()->Assign_Values(&Parameters);
	Mosaic.Set_Parameter("TARGET_DEFINITION", 1);	// grid or grid system

	CSG_Parameter_Grid_List	*pList_Grid	= Mosaic.Get_Parameter("GRIDS")->asGridList();

	for(int z=0; z<pGrids->Get_NZ(); z++)
	{
		pList_Grid->Del_Items();

		for(int i=0; i<pList_Grids->Get_Item_Count(); i++)
		{
			if( z < pList_Grids->Get_Grids(i)->Get_NZ() )
			{
				pList_Grid->Add_Item(pList_Grids->Get_Grids(i)->Get_Grid_Ptr(z));
			}
			else if( z == pList_Grids->Get_Grids(i)->Get_NZ() )	// throw warning only once
			{
				Message_Fmt("\n[%s] %s: [%d] %s", _TL("Warning"), _TL("incompatible input"), i + 1, pList_Grids->Get_Grids(i)->Get_Name());
			}
		}

		pMosaic->Get_Attributes(z).Assign(&pGrids->Get_Attributes(z));

		Mosaic.Set_Parameter("TARGET_OUT_GRID", (void *)pMosaic->Get_Grid_Ptr(z));

		if( !Mosaic.Execute() )
		{
			Error_Fmt("%s (z = %d)", _TL("mosaicking failed"), z + 1);

			return( false );
		}
	}

	//-----------------------------------------------------
	DataObject_Add(pMosaic);
	DataObject_Set_Parameters(pMosaic, pGrids);

	if( has_GUI() )
	{
		pMosaic->Set_Name(Parameters("NAME")->asString());
	}

	return( true );
}


///////////////////////////////////////////////////////////
//														 //
//														 //
//														 //
///////////////////////////////////////////////////////////

//---------------------------------------------------------
