How do I create a colormap in VTK?

Question

I created a simple unstructured square in VTK:

x = [0,10,0,10]
y = [0, 0, 10, 10]
z = [0,0,0,0]
data = np.asarray([x,y,z]).T
for i in range(0, len(x)):
    points.InsertPoint(i, data[i])
quad = [2,3,1,0]
ugrid.InsertNextCell(vtk.VTK_QUAD, 4, quad)
ugrid.SetPoints(points)

Say I wanted to create a colormap of the temperature across the square. I know the temperature at the corners:

 temp = [0,20,40,60]

How can I color the entire square knowing these values?

VTK provides one example to create a colormap in their tutorials (the ColoredElevationMap tutorial), however, I don’t completely understand it and I believe there is another simpler way to create a colormap in VTK that I don’t know of.

Asked By: J Houseman

||

Source

Answer 1

You should add your data array and set it as the scalars (= default array to use in VTK, particularly for coloring)

temperature = vtk.vtkIntArray()
temperature.SetName("Temp")
temp = [00,20,40,60]
for t in temp:
    temperature.InsertNextValue(t)

ugrid.GetPointData().SetScalars(temperature)

Then in the rendering part, this array will be used by default for coloration. You still have to update the color range:

mapper.SetScalarRange(ugrid.GetScalarRange())

You can take a look to this example (edit: update link thanks to @paulo-carvalho)

Answered By: Nico Vuaille

Answer 2

Adding to Nico Vuaille’s answer. The color of the map can be changed using a lookup table such as:

lut = vtk.vtkLookupTable()
lut.SetHueRange(0, 0)
lut.SetSaturationRange(0, 0)
lut.SetValueRange(0.2, 1.0)
lut.Build()

and

Mapper.SetLookupTable(lut)

Answered By: J Houseman

How do I create a colormap in VTK?

Question:

Answers: