CODEWITHSUNDEEP
python-3.xvtkpoint-cloudscolormap
the_parzival
the_parzival

Reputation: 374

Color a large point cloud using height value in VTK

I am using VTK python bindings to color a large point cloud based on the height of the points. I am able to color them properly using vtk.vtkLookupTable, and looping through all the points and getting color based on z value using GetColor function, but looping through large number of points is very slow. Below mentioned code will show how i did that Code : 

lookUpTable = vtk.vtkLookupTable()
lookUpTable.SetTableRange(minz,maxz)
lookUpTable.Build()

# Create a unsigned char array to color
uCharArray = vtk.vtkUnsignedCharArray()
uCharArray.SetNumberOfComponents(3)
uCharArray.SetName("colors")

After we have created LookupTable and UnsignedCharArray, i am looping through all the points and filling up the above defined array.

# Assign color by extracting each color
for i in range(outputPolyData.GetNumberOfPoints()):
    point = outputPolyData.GetPoint(i)
    # Get the color from lookup table
    color = [0]*3
    lookUpTable.GetColor(point[2],color)
    # Convert each color to 255
    for j in range(len(color)):
        color[j] = int(255 * color[j])
    uCharArray.InsertTypedTuple(i,color)


# # Set Scalars
outputPolyData.GetPointData().SetScalars(uCharArray)

The output will be enter image description here

But to color 1000000 points, its taking 3.180 seconds. I actually have 8000000 points. It would take a lot of time if i loop over every point to assign color. I am pretty sure there would be other way to do this. If any one can point me in the right direction, i would be glad.

Upvotes: 1

Views: 1317

Answers (1)

the_parzival
the_parzival

Reputation: 374

I solved it using MapScalars function in vtkLookupTable. This function is used inside the class to generate lookup tables. I passed the Z array to the function, it gave me an array of colors.

array = lookUpTable.MapScalars(vtkzArray,vtk.VTK_COLOR_MODE_DEFAULT,-1)
outputPolyData.GetPointData().SetScalars(array)

Here vtkzArray should be of type vtkDataArray. I converted numpy array to vtkDataArray using vtk_to_numpy from numpy_support class.

Upvotes: 3

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