discrete color scheme for vtk data

ParaView Support
1

Hello,
I have a vtk data file, with several number of cellIDs (in this case 18 different IDs) is there any way to automatically do a discrete color scheme (that has no transition between different values of IDs, such as blot for example) but that it adapts to the number of IDs? as:
a. I dont know how many I will have for a specific file
b. there can be more IDs than KAAMS scheme (which it looks like to be the one with more colors)
here is a simple example of a vtk file to treat:
vtkForPropagationGroups.vtk (18.1 KB)

thanks in advance.

2

There is no way to “generate” colors for a arbitrary number of values.

What you can is:

  1. Use the biggest categorical colormap (BlueObelisk without annotations), this gives you 30 different colors

image
image1182Ă—770 23.4 KB

  1. Use a linear colormap in step mode

    image
    image1182Ă—770 26 KB

  2. Create your own color maps with hundreds of colors for categorical coloring

1 Like
3

Hello mathieu,
I just went a different way that will be more usefull in the end (not exactly what I was asking on my original post for sure, but maybe functional for someone that finds this post).

def createDisplayOfPropagationGroups(vtkReaderFilter=[]):
    if vtkReaderFilter==[]:
        vtkReaderFilter= GetActiveSource()
    renderView = GetActiveView()
    
    data=dsa.WrapDataObject(servermanager.Fetch(vtkReaderFilter))
    N=len(set(data.CellData['CellEntityIds']))
    thresholds=[]
    threshold1Displays=[]
    for i in range(N):
        thresholds.append(Threshold(registrationName='Propagation group '+str(i), Input=vtkReaderFilter, Scalars = ['CELLS', 'CellEntityIds'],LowerThreshold = i-0.01, UpperThreshold=i+0.01))
        threshold1Displays.append(Show(thresholds[-1], renderView, 'UnstructuredGridRepresentation'))
        threshold1Displays[-1].LineWidth = 3.0 
        threshold1Displays[-1].Representation = 'Surface'
        threshold1Displays[-1].SetScalarBarVisibility(renderView, True)
        thresholds[-1].UpdatePipeline()
    Hide(vtkReaderFilter, renderView)
    renderView.Update()
    return

the only issue I am having right now is that eventhought I am creating the displays objects (with the Show() function) the object are created and everything but they are not shown in the layout view.

1 Like