[vtkusers] vtkPointCloudFilter changes type of data arrays to float

[Sergey Alexandrov]

Hi Bill,

Thanks for the prompt reply and the patch. I see that you have
submitted a merge
request <https://gitlab.kitware.com/vtk/vtk/merge_requests/2393> already,
so looking
forward to have this fixed in the next release. In the meanwhile I'll just
copy the patched vtkPointCloudFilter into
my project.

Cheers,
Sergey


On Wed, Jan 18, 2017 at 5:47 PM Bill Lorensen <bill.lorensen at gmail.com>
wrote:

> PointCloudFilter was promoting all integral arrays to float.
> I am working on a patch and test.
>
> In the meantime you could apply the following changes:
> diff --git a/Filters/Points/vtkPointCloudFilter.cxx
> b/Filters/Points/vtkPointCloudFilter.cxx
> index d9b3b6f..63fa046 100644
> --- a/Filters/Points/vtkPointCloudFilter.cxx
> +++ b/Filters/Points/vtkPointCloudFilter.cxx
> @@ -48,7 +48,7 @@ struct MapPoints
>              vtkIdType *map, vtkPointData *inPD, vtkPointData *outPD) :
>      InPoints(inPts), OutPoints(outPts), PointMap(map)
>    {
> -      this->Arrays.AddArrays(numOutPts, inPD, outPD);
> +    this->Arrays.AddArrays(numOutPts, inPD, outPD, 0.0, false);
>    }
>
>    void operator() (vtkIdType ptId, vtkIdType endPtId)
> @@ -97,7 +97,7 @@ struct MapOutliers
>                vtkIdType *map, vtkPointData *inPD, vtkPointData *outPD2) :
>      InPoints(inPts), OutPoints(outPts), PointMap(map)
>    {
> -      this->Arrays.AddArrays(numOutPts, inPD, outPD2);
> +    this->Arrays.AddArrays(numOutPts, inPD, outPD2, 0.0, false);
>    }
>
>
> On Wed, Jan 18, 2017 at 9:50 AM, Bill Lorensen <bill.lorensen at gmail.com>
> wrote:
> > Looks like a bug. I'll take a look today.
> >
> >
> > On Wed, Jan 18, 2017 at 5:46 AM, Sergey Alexandrov
> > <alexandrov88 at gmail.com> wrote:
> >> Hey,
> >>
> >> I was writing a custom point cloud filtering algorithm and came across
> the
> >> vtkPointCloudFilter class,
> >> which looks like a convenient base for this kind of filter. However, in
> my
> >> opinion it behaves strangely
> >> when it comes to the handling of data arrays bundled with the points.
> The
> >> documentation says that
> >> "The filter copies point attributes from input to output consistent
> with the
> >> filtering operation", and
> >> indeed it does, but while copying it changes the type of the attribute
> >> arrays, everything becomes a
> >> float! Here is a small example that uses vtkRadiusOutlierRemoval
> (derived
> >> from vtkPointCloudFilter).
> >> I create several points with an unsigned char attribute, and pass it
> through
> >> the filter.
> >>
> >>
> >> #include <iostream>
> >>
> >> #include <vtkPoints.h>
> >> #include <vtkPolyData.h>
> >> #include <vtkPointData.h>
> >> #include <vtkSmartPointer.h>
> >> #include <vtkUnsignedCharArray.h>
> >> #include <vtkRadiusOutlierRemoval.h>
> >>
> >> int main(int argc, const char** argv)
> >> {
> >>   const double pt1[3] = { 0, 0, 0};
> >>   const double pt2[3] = { 1, 0, 0};
> >>   const double pt3[3] = { 2, 0, 0};
> >>
> >>   auto points = vtkSmartPointer<vtkPoints>::New();
> >>   points->SetDataTypeToDouble();
> >>   points->InsertNextPoint(pt1);
> >>   points->InsertNextPoint(pt2);
> >>   points->InsertNextPoint(pt3);
> >>
> >>   auto labels = vtkSmartPointer<vtkUnsignedCharArray>::New();
> >>   labels->SetName("label");
> >>   labels->SetNumberOfComponents(1);
> >>   labels->InsertNextValue(1);
> >>   labels->InsertNextValue(2);
> >>   labels->InsertNextValue(3);
> >>
> >>   auto poly_data = vtkSmartPointer<vtkPolyData>::New();
> >>   poly_data->SetPoints(points);
> >>   poly_data->GetPointData()->AddArray(labels);
> >>
> >>   auto outlier_removal =
> vtkSmartPointer<vtkRadiusOutlierRemoval>::New();
> >>   outlier_removal->SetInputData(poly_data);
> >>   outlier_removal->SetRadius(1.5);
> >>   outlier_removal->SetNumberOfNeighbors(2);
> >>   outlier_removal->Update();
> >>
> >>   auto output = outlier_removal->GetOutputDataObject(0);
> >>   auto attributes = output->GetAttributes(0);
> >>
> >>   std::cout << "Output attributes: " << attributes->GetArrayName(0) <<
> ",
> >> type: " << attributes->GetArray(0)->GetDataTypeAsString() << std::endl;
> >>
> >>   return 0;
> >> }
> >>
> >>
> >> This example prints
> >>
> >>> Output attributes: label, type: float
> >>
> >>
> >> So what happens is that the "label" attribute, that was originally of
> type
> >> unsigned char, becomes a
> >> float attribute in the output of the filter.
> >>
> >> It this behavior a bug or a feature? Or maybe I am missing a flag
> somewhere
> >> which controls this
> >> behavior?
> >>
> >> Cheers,
> >> Sergey
> >>
> >>
> >>
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> >
> >
> >
> > --
> > Unpaid intern in BillsBasement at noware dot com
>
>
>
> --
> Unpaid intern in BillsBasement at noware dot com
>
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