[vtkusers] vtkPointCloudFilter changes type of data arrays to float

[Bill Lorensen]

Sergey,

Just merged into master. Thanks for providing the example that
illustrated the problem.

Bill

On Thu, Jan 19, 2017 at 4:10 AM, Sergey Alexandrov
<alexandrov88 at gmail.com> wrote:
> Hi Bill,
>
> Thanks for the prompt reply and the patch. I see that you have submitted a
> merge request 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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