[vtkusers] Uneven colors after the vtkButterflySubdivisionFilter

[Bill Lorensen]

div,

Why not use the Loop subdivision?


On Sun, Apr 21, 2013 at 8:00 AM, Bill Lorensen <bill.lorensen at gmail.com>wrote:

> David,
>
> Butterfly is approximating. The vertices it generates do not lie on the
> original surface.
>
>
> On Sat, Apr 20, 2013 at 6:31 PM, David Gobbi <david.gobbi at gmail.com>wrote:
>
>> The vtkProbeFilter works fine with RGB scalars, doesn't it?  So it
>> should be possible to put a probe filter after the subdivision filter
>> to re-interpolate the scalars from the original data set.
>>
>> On Sat, Apr 20, 2013 at 3:51 PM, Bill Lorensen <bill.lorensen at gmail.com>
>> wrote:
>> > I was able to duplicate your problem. I believe the problem is trying to
>> > approximate the unsigned char 3-component colors. Butterfly is an
>> > approximating subdivision scheme, while loop is an interpolating
>> scheme. I
>> > think if you assigned scalar float, single component values and mapper
>> them
>> > through a lookup table you would get good results. But I'm not sure that
>> > would accomplish what you want.
>> >
>> >
>> >
>> > On Sat, Apr 20, 2013 at 2:23 PM, Bill Lorensen <bill.lorensen at gmail.com
>> >
>> > wrote:
>> >>
>> >> This better. Just to be sure, I assume this code also produces bad
>> >> results?
>> >>
>> >>
>> >>
>> >> On Sat, Apr 20, 2013 at 1:39 PM, DivyaS <div.anand141 at gmail.com>
>> wrote:
>> >>>
>> >>> Sure, please check this code - I have removed all the unnecessary
>> code. I
>> >>> have added comments for each of the steps.
>> >>>
>> >>>             //Defining a cylinder source.
>> >>>             vtkCylinderSource cylinderSource =
>> vtkCylinderSource.New();
>> >>>             cylinderSource.Update();
>> >>>
>> >>>             vtkTriangleFilter triangles = vtkTriangleFilter.New();
>> >>>             triangles.SetInput(cylinderSource.GetOutput());
>> >>>             triangles.Update();
>> >>>             vtkPolyData originalMesh;
>> >>>             originalMesh = triangles.GetOutput();
>> >>>
>> >>>             vtkUnsignedCharArray colors = vtkUnsignedCharArray.New();
>> >>>             colors.SetNumberOfComponents(3);
>> >>>             colors.SetNumberOfTuples(originalMesh.GetNumberOfPolys());
>> >>>             colors.SetName("Colors");
>> >>>
>> >>>             //Creating an array to store the values according to which
>> >>> the
>> >>> colors are selected.
>> >>>             //Values are inserted for each of the points in the
>> polydata
>> >>>             int[] colorAT = new int[originalMesh.GetNumberOfPolys()];
>> >>>             for (int i = 0; i < originalMesh.GetNumberOfPolys(); i++)
>> >>>             {
>> >>>                 colorAT[i] = i;
>> >>>             }
>> >>>
>> >>>             int activationTime;
>> >>>             //Loop to select colors for each of the points in the
>> >>> polydata.
>> >>>             for (int i = 0; i < originalMesh.GetNumberOfPolys(); i++)
>> >>>             {
>> >>>                 activationTime = colorAT[i];
>> >>>                 if (activationTime > 0 && activationTime < 5)
>> >>>                 {
>> >>>                     //Black
>> >>>                     colors.InsertTuple3(i, 255, 255, 0);
>> >>>                 }
>> >>>                 else if (activationTime > 4 && activationTime < 10)
>> >>>                 {
>> >>>                     //Blue
>> >>>                     colors.InsertTuple3(i, 0, 0, 255);
>> >>>                 }
>> >>>                 else if (activationTime > 9 && activationTime < 300)
>> >>>                 {
>> >>>                     //Red
>> >>>                     colors.InsertTuple3(i, 255, 0, 0);
>> >>>                 }
>> >>>             }
>> >>>             originalMesh.GetPointData().SetScalars(colors);
>> >>>
>> >>>             //Subdivision.
>> >>>             int numberOfSubdivisions = 4;
>> >>>             vtkPolyDataAlgorithm subdivisionFilter =
>> >>> vtkButterflySubdivisionFilter.New();
>> >>>
>> >>>
>> >>>
>> ((vtkButterflySubdivisionFilter)subdivisionFilter).SetNumberOfSubdivisions(numberOfSubdivisions);
>> >>>             subdivisionFilter.SetInput(originalMesh);
>> >>>             subdivisionFilter.Update();
>> >>>
>> >>>             vtkRenderWindow renderWindow =
>> >>> renderWindowControl1.RenderWindow;
>> >>>             vtkRenderer renderer = vtkRenderer.New();
>> >>>
>> >>>             //Create a mapper and actor
>> >>>             vtkPolyDataMapper mapper = vtkPolyDataMapper.New();
>> >>>
>> mapper.SetInputConnection(subdivisionFilter.GetOutputPort());
>> >>>             vtkActor actor = vtkActor.New();
>> >>>             actor.SetMapper(mapper);
>> >>>
>> >>>             renderer.AddActor(actor);
>> >>>             renderer.SetBackground(0, 0, 0);
>> >>>             renderer.ResetCamera();
>> >>>             renderWindow.AddRenderer(renderer);
>> >>>             renderWindow.Render();
>> >>>
>> >>>
>> >>>
>>
>
>
>
> --
> Unpaid intern in BillsBasement at noware dot com
>



-- 
Unpaid intern in BillsBasement at noware dot com
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