Color specific mesh elements

Support
1

Hi!
I want to plot my STL-Model (or general 3D object) using VTK. For this, I used the STLReader.
My next step is to give some facets of the model different colors, so e.g.:
Face 1-10 shall be red
Face 11 - 20 shall be blue.

Since I am relatively new to VTK and the intellisense of my IDE is not giving me further interesting options, it’s hard for me to achieve this task.
I read a lot about color lookup tables and scalararrays which are applied to the mapper but somehow, all I’ve done so far does not work.
I am using Python for VTK.

Can somebody help me here?

Best regards
Benny

2

Benny,

These examples from the VTK Examples Project. may help. They coth color individual cells.

  1. ColorCells
  2. ColorCellsWithRGB

Enjoy VTK,

Bill

3

With vtkplotter helper module:

from vtkplotter import *

s = load(datadir+'shuttle.stl')

cols, als = [], []
for i in range(s.NCells()):
    cols.append(i) # i-th color
    als.append(i/s.NCells()) #opacity

s.colorCellsByArray(cols, als).lw(1).show()

Screenshot%20from%202019-08-01%2001-42-12

4

Thanks for your answers, I solved the problem using following exemplary code:

reader = vtkOFFReader()
reader.SetFileName(meshfile)

vtkpolydata = reader.GetPolyData()
scalarArray = numpy_support.numpy_to_vtk(scalararray)

vtkpolydata.GetCellData().SetScalars(scalarArray)

lut = vtk.vtkLookupTable()
lut.SetNumberOfTableValues(len(labels.Categories))
lut.SetTableRange(0,len(labels.Categories)-1)
lut.SetHueRange(0.2,0.667);
lut.Build()