1 // =========================================================================
2 // @author Leonardo Florez Valencia
3 // @email florez-l@javeriana.edu.co
4 // =========================================================================
6 #ifndef __fpa__Image__SkeletonFilter__hxx__
7 #define __fpa__Image__SkeletonFilter__hxx__
9 #include <itkImageRegionIteratorWithIndex.h>
10 #include <itkMinimumMaximumImageCalculator.h>
12 // -------------------------------------------------------------------------
13 template< class _TImage, class _TScalar >
14 void fpa::Image::SkeletonFilter< _TImage, _TScalar >::
15 SetInput( const TScalarImage* image )
20 // -------------------------------------------------------------------------
21 template< class _TImage, class _TScalar >
22 void fpa::Image::SkeletonFilter< _TImage, _TScalar >::
23 SetInput( const TImage* image )
25 this->m_DistanceMap->SetInput( image );
26 this->Superclass::SetInput( this->m_DistanceMap->GetOutput( ) );
29 // -------------------------------------------------------------------------
30 template< class _TImage, class _TScalar >
31 _TImage* fpa::Image::SkeletonFilter< _TImage, _TScalar >::
34 return( this->m_DistanceMap->GetInput( ) );
37 // -------------------------------------------------------------------------
38 template< class _TImage, class _TScalar >
39 const _TImage* fpa::Image::SkeletonFilter< _TImage, _TScalar >::
42 return( this->m_DistanceMap->GetInput( ) );
45 // -------------------------------------------------------------------------
46 template< class _TImage, class _TScalar >
47 typename fpa::Image::SkeletonFilter< _TImage, _TScalar >::
48 TSkeleton* fpa::Image::SkeletonFilter< _TImage, _TScalar >::
52 dynamic_cast< TSkeleton* >(
53 this->itk::ProcessObject::GetOutput( this->m_SkeletonIdx )
58 // -------------------------------------------------------------------------
59 template< class _TImage, class _TScalar >
60 typename fpa::Image::SkeletonFilter< _TImage, _TScalar >::
61 TMarks* fpa::Image::SkeletonFilter< _TImage, _TScalar >::
65 dynamic_cast< TMarks* >(
66 this->itk::ProcessObject::GetOutput( this->m_MarksIdx )
71 // -------------------------------------------------------------------------
72 template< class _TImage, class _TScalar >
73 fpa::Image::SkeletonFilter< _TImage, _TScalar >::
76 m_SeedFromMaximumDistance( false )
78 this->m_DistanceMap = TDistanceMap::New( );
79 this->m_DistanceMap->InsideIsPositiveOn( );
80 this->m_DistanceMap->SquaredDistanceOff( );
81 this->m_DistanceMap->UseImageSpacingOn( );
83 unsigned int nOutputs = this->GetNumberOfRequiredOutputs( );
84 this->SetNumberOfRequiredOutputs( nOutputs + 2 );
85 this->m_SkeletonIdx = nOutputs;
86 this->m_MarksIdx = nOutputs + 1;
88 typename TSkeleton::Pointer skeleton = TSkeleton::New( );
89 typename TMarks::Pointer marks = TMarks::New( );
90 this->SetNthOutput( this->m_SkeletonIdx, skeleton.GetPointer( ) );
91 this->SetNthOutput( this->m_MarksIdx, marks.GetPointer( ) );
94 // -------------------------------------------------------------------------
95 template< class _TImage, class _TScalar >
96 fpa::Image::SkeletonFilter< _TImage, _TScalar >::
101 // -------------------------------------------------------------------------
102 template< class _TImage, class _TScalar >
103 void fpa::Image::SkeletonFilter< _TImage, _TScalar >::
106 // Prepare distance map
107 this->m_DistanceMap->Update( );
111 if( this->m_SeedFromMaximumDistance )
113 typedef itk::MinimumMaximumImageCalculator< TScalarImage > _TMinMax;
114 typename _TMinMax::Pointer minmax = _TMinMax::New( );
115 minmax->SetImage( this->m_DistanceMap->GetOutput( ) );
117 seed = minmax->GetIndexOfMaximum( );
120 seed = *( this->BeginSeeds( ) );
121 this->m_Seeds.clear( );
122 this->m_Seeds.insert( seed );
124 // Prepare skeleton candidates queue
125 this->m_SkeletonQueue.clear( );
128 this->Superclass::GenerateData( );
132 std::vector< TVertex > end_points;
133 this->_EndPoints( end_points, A );
134 this->_Skeleton( end_points, A );
137 // -------------------------------------------------------------------------
138 template< class _TImage, class _TScalar >
139 void fpa::Image::SkeletonFilter< _TImage, _TScalar >::
140 _SetOutputValue( const TVertex& vertex, const TOutputValue& value )
142 typedef typename _TSkeletonQueue::value_type _TSkeletonQueueValue;
144 this->Superclass::_SetOutputValue( vertex, value );
145 double d = double( this->m_DistanceMap->GetOutput( )->GetPixel( vertex ) );
146 if( d >= double( 0 ) )
148 // Update skeleton candidates
150 double v = double( value ) / ( d * d );
151 this->m_SkeletonQueue.insert( _TSkeletonQueueValue( v, vertex ) );
156 // -------------------------------------------------------------------------
157 template< class _TImage, class _TScalar >
158 void fpa::Image::SkeletonFilter< _TImage, _TScalar >::
159 _EndPoints( std::vector< TVertex >& end_points, _TAdjacencies& A )
161 typedef typename _TSkeletonQueue::value_type _TSkeletonQueueValue;
163 TMarks* marks = this->GetMarks( );
164 TMST* mst = this->GetMinimumSpanningTree( );
165 typename TImage::SpacingType spac = marks->GetSpacing( );
168 marks->SetLargestPossibleRegion( mst->GetLargestPossibleRegion( ) );
169 marks->SetRequestedRegion( mst->GetRequestedRegion( ) );
170 marks->SetBufferedRegion( mst->GetBufferedRegion( ) );
171 marks->SetSpacing( mst->GetSpacing( ) );
172 marks->SetOrigin( mst->GetOrigin( ) );
173 marks->SetDirection( mst->GetDirection( ) );
175 marks->FillBuffer( 0 );
177 // BFS from maximum queue
178 while( this->m_SkeletonQueue.size( ) > 0 )
181 typename _TSkeletonQueue::iterator nIt = this->m_SkeletonQueue.begin( );
182 _TSkeletonQueueValue n = *nIt;
183 this->m_SkeletonQueue.erase( nIt );
185 // Mark it and update end-points
186 unsigned char m = marks->GetPixel( n.second );
189 marks->SetPixel( n.second, 1 );
190 end_points.push_back( n.second );
193 TVertex it = n.second;
194 TVertex p = mst->GetParent( it );
197 this->_MarkSphere( it );
199 p = mst->GetParent( it );
202 this->_MarkSphere( it );
208 // -------------------------------------------------------------------------
209 template< class _TImage, class _TScalar >
210 void fpa::Image::SkeletonFilter< _TImage, _TScalar >::
211 _Skeleton( const std::vector< TVertex >& end_points, _TAdjacencies& A )
213 typedef typename TSkeleton::TPath _TPath;
214 typedef itk::Image< unsigned long, TImage::ImageDimension > _TTagsImage;
216 TMST* mst = this->GetMinimumSpanningTree( );
217 TSkeleton* skeleton = this->GetSkeleton( );
220 typename _TTagsImage::Pointer tags = _TTagsImage::New( );
221 tags->SetLargestPossibleRegion( mst->GetLargestPossibleRegion( ) );
222 tags->SetRequestedRegion( mst->GetRequestedRegion( ) );
223 tags->SetBufferedRegion( mst->GetBufferedRegion( ) );
225 tags->FillBuffer( 0 );
226 for( TVertex it: end_points )
228 TVertex p = mst->GetParent( it );
231 tags->SetPixel( it, tags->GetPixel( it ) + 1 );
233 p = mst->GetParent( it );
236 tags->SetPixel( it, tags->GetPixel( it ) + 1 );
240 // Build paths (branches)
241 for( TVertex it: end_points )
243 TVertex p = mst->GetParent( it );
245 typename _TPath::Pointer path = _TPath::New( );
246 path->SetReferenceImage( mst );
249 if( tags->GetPixel( sIdx ) != tags->GetPixel( it ) )
251 // Ok, a new branch has been added
252 path->AddVertex( it );
253 skeleton->AddBranch( path );
255 // Update a new starting index
256 path = _TPath::New( );
257 path->SetReferenceImage( mst );
261 path->AddVertex( it );
263 p = mst->GetParent( it );
267 // Finally, add last branch
268 path->AddVertex( it );
269 skeleton->AddBranch( path );
274 // -------------------------------------------------------------------------
275 template< class _TImage, class _TScalar >
276 void fpa::Image::SkeletonFilter< _TImage, _TScalar >::
277 _MarkSphere( const TVertex& idx )
279 typedef itk::ImageRegionIteratorWithIndex< TMarks > _TMarksIt;
281 static const double _eps = std::sqrt( double( TImage::ImageDimension + 1 ) );
282 const TScalarImage* dmap = this->m_DistanceMap->GetOutput( );
283 TMarks* marks = this->GetMarks( );
284 typename TImage::SpacingType spac = dmap->GetSpacing( );
285 typename TImage::RegionType region = dmap->GetRequestedRegion( );
287 typename TImage::PointType cnt;
288 dmap->TransformIndexToPhysicalPoint( idx, cnt );
289 double r = double( dmap->GetPixel( idx ) ) * _eps;
292 for( unsigned int d = 0; d < TImage::ImageDimension; ++d )
294 long off = long( std::ceil( r / double( spac[ d ] ) ) );
297 i0[ d ] = idx[ d ] - off;
298 i1[ d ] = idx[ d ] + off;
300 if( i0[ d ] < region.GetIndex( )[ d ] )
301 i0[ d ] = region.GetIndex( )[ d ];
303 if( i1[ d ] >= region.GetIndex( )[ d ] + region.GetSize( )[ d ] )
304 i1[ d ] = region.GetIndex( )[ d ] + region.GetSize( )[ d ] - 1;
308 typename TImage::SizeType size;
309 for( unsigned int d = 0; d < TImage::ImageDimension; ++d )
310 size[ d ] = i1[ d ] - i0[ d ] + 1;
312 typename TImage::RegionType neighRegion;
313 neighRegion.SetIndex( i0 );
314 neighRegion.SetSize( size );
316 _TMarksIt mIt( marks, neighRegion );
317 for( mIt.GoToBegin( ); !mIt.IsAtEnd( ); ++mIt )
319 TVertex w = mIt.GetIndex( );
320 typename TImage::PointType p;
321 marks->TransformIndexToPhysicalPoint( w, p );
327 #endif // __fpa__Image__SkeletonFilter__hxx__