[vtkusers] Iterative closest point transform for point clouds - need some help

[Sylvain Jaume]

Hi Vikas,

You could try to create vertices with vtkMaskPoints before the ICP filter:

vtkMaskPoints *maskPoints = vtkMaskPoints::New();
maskPoints->SetInput(polyData1);
maskPoints->SetMaximumNumberOfPoints(numPoints);
maskPoints->GenerateVerticesOn();

You don't need to cast polyData1. Use vtkPolyDataMaper instead of 
vtkDataSetMapper.

Cheers,
Sylvain

Vikas Singh wrote:

>Hi Sylvain:
>
>Unfortunately, that doesnt work.  I mentioned that in my email
>(attached below) that if I do not do a delaunay triangulation and call
>icpt directly as
>
>_icpt->SetSource(polydata_1);
>_icpt->SetTarget(polydata_2);
>
>it gives me a segmentation fault and the following error message:
>ERROR: In /usr/local/VTK/Filtering/vtkCellLocator.cxx, line 1190
>vtkCellLocator (0x8093b88): No cells to subdivide.
>
>Same error message even if I typecast it.
>
>But If I do a Delaunay, I avoid the error message and seg fault.
>However, after applying the transformation on the source cloud set, I
>cannot see the point set when it renders it.
>See partial code below:
>
> // Iterative Closest Point Transform
>  vtkIterativeClosestPointTransform *_icpt =
>vtkIterativeClosestPointTransform::New();
>  _icpt->GetLandmarkTransform()->SetModeToRigidBody();
>  _icpt->StartByMatchingCentroidsOn();
>  _icpt->SetMaximumNumberOfIterations(100.);
>
>// del_1 and del_2 are the delaunay triangulations for first and
>second point clouds.
>  _icpt->SetSource((vtkDataSet *)del_1->GetOutput());
>  cout << "Calling icpt" << endl;
>  _icpt->SetTarget((vtkDataSet *)del_2->GetOutput());
>
>  _icpt->Update();
>
>  cout << "done icpt" << endl;
>
>  // Now lets tranform the data
>  vtkTransformPolyDataFilter* transformer = vtkTransformPolyDataFilter::New();
>  transformer->SetTransform(_icpt);
>
>  transformer->SetInput((vtkPolyData*)polydata_1);
>  transformer->Update();
>  transformer->PrintSelf(std::cout,0);
>
>  // map for displaying
>
>  vtkDataSetMapper *surface_mapper_1 = vtkDataSetMapper::New();
>
>  //surface_mapper_1->SetInput((vtkDataSet*)del_1->GetOutput());
>  // if i do this ^^^^^^^^^^^^^ it shows the untransformed first point cloud
>  // and the one below does not show anything (I want it to show the
>  // the transformed (aligned) point cloud
>  surface_mapper_1->SetInput(transformer->GetOutput());
>
>  vtkDataSetMapper *surface_mapper_2 = vtkDataSetMapper::New();
>  surface_mapper_2->SetInput((vtkDataSet*)_icpt->GetTarget());
>
>  // Create an actor for cloud 1.
>  vtkActor* actor_1 = vtkActor::New();
>  actor_1->SetMapper(surface_mapper_1);
>  actor_1->GetProperty()->SetRepresentationToPoints();
>  actor_1->GetProperty()->SetColor(1,1,1);
>
>  // create an actor for cloud 2
>  vtkActor* actor_2 = vtkActor::New();
>  actor_2->SetMapper(surface_mapper_2);
>  actor_2->GetProperty()->SetRepresentationToPoints();
>  actor_2->GetProperty()->SetColor(0,1,1);
>
>......and then the rendering part.
>
>
>Any suggestions ?
>
>--Vikas
>
>
>On 11/7/05, Sylvain Jaume <sylvain.jaume at kitware.com> wrote:
>  
>
>>Hi Vikas,
>>
>>vtkIterativeClosestPointTransform gives a transform. You need to apply
>>the resulting transform to your input dataset using
>>vtkTransformPolyDataFilter. You don't need to use vtkDelaunay3D, nor to
>>type cast your datasets.
>>
>>Cheers,
>>Sylvain
>>
>>Vikas Singh wrote:
>>
>>    
>>
>>>Hello!
>>>
>>>I am a newbie to VTK and need some help with ICPT. Been trying all
>>>sorts of things since today morning including the VTK User's guide and
>>>the online documentation but nothing has worked so far. Seems to me
>>>that the problem is simple for someone who knows VTK well.
>>>
>>>I am trying to randomly generate point clouds and align them (as a start).
>>>
>>>vtkPolyData* polydata_1 = vtkPolyData::New();
>>>vtkDelaunay3D* del_1    = vtkDelaunay3D::New();
>>>vtkPoints* cloud_1         = vtkPoints::New();
>>>
>>>static float mypoint_1[3];
>>>
>>>for (int i = 0; i < 50; i++)
>>>   {
>>>     mypoint_1[0] = drand48()*50;
>>>     mypoint_1[1] = drand48()*50;
>>>     mypoint_1[2] = drand48()*50;
>>>
>>>     cloud_1->InsertNextPoint(mypoint_1);
>>>   }
>>>
>>> polydata_1->SetPoints(cloud_1);
>>>
>>> int num_of_points_1 = polydata_1->GetPoints()->GetNumberOfPoints();
>>> cout << "in all, num of points in cloud 1 is " << num_of_points_1 << endl;
>>>
>>> del_1->SetInput((vtkPointSet*)polydata_1);
>>> del_1->SetTolerance(0.01);
>>> del_1->PrintSelf(std::cout,0);
>>>
>>>I repeat the same for cloud 2 - variable names end with "_2".
>>>
>>>
>>>Then I call ICPT as follows:
>>>
>>>vtkIterativeClosestPointTransform *_icpt =
>>>vtkIterativeClosestPointTransform::New();
>>>_icpt->GetLandmarkTransform()->SetModeToRigidBody();
>>>_icpt->StartByMatchingCentroidsOn();
>>>_icpt->SetMaximumNumberOfIterations(10);
>>>
>>>_icpt->SetSource((vtkDataSet *)del_1->GetOutput());
>>>cout << "Calling icpt" << endl;
>>>_icpt->SetTarget((vtkDataSet *)del_2->GetOutput());
>>>
>>>_icpt->Update();
>>>
>>>
>>>To this it gives me an error
>>>
>>>ERROR: In /usr/local/VTK/Hybrid/vtkIterativeClosestPointTransform.cxx, line 274
>>>vtkIterativeClosestPointTransform (0x80650e0): Can't execute with NULL or empty
>>>input
>>>
>>>I think that up until the delaunay triangulation, it is working ok - I
>>>rendered it and it is alright. If I do not do a delaunay triangulation
>>>and typecast cloud_1 and cloud_2 directly it never returns from ICPT.
>>>
>>>any pointers, please?
>>>
>>>VS.
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>>>
>>>
>>>      
>>>
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