Vedo: Discrete Colorbar

[jrdkr]

I think Ive got a simple question but i wasn't able to find anythink about my question in the documentation or examples. I would therefore be very grateful for any advice on how to solve the problem.

Iam trying to visualize a segmented mesh. So I wanted to create a custom colormap with a unique color for each segment/cluster. So my problem is, that Iam not able to create a discrete colorbar (pyplot: spacing='proportional'). I added an image with my current state. Ive got 3 cluster and want to have each in a unique color and a matching colorbar.

Thanks for your support!

scals = labels+1
meshVTK = trimesh2vtk(mesh)
cols = makePalette("grey", "red", np.max(np.unique(labels))+1, hsv=True)
meshVTK.cellColors(scals, cmap = cols)
meshVTK.legend('Found Clusters')
meshVTK.addScalarBar(c='k', vmin=min(scals), vmax=max(scals))
meshVTK.show(bg='white', axes=0)

[marcomusy]

@jrdkr consider this possible solution:

import trimesh
from vtkplotter import trimesh2vtk

mesh = trimesh.creation.icosphere()

meshVTK = trimesh2vtk(mesh)

cols = []
for i in range(meshVTK.NCells()):
    if i<200:
        cols.append([1,0,0])
    elif i<300:
        cols.append([1,1,0])
    else:
        cols.append([0.5,0.5,0.5])

meshVTK.cellColors(cols, mode='colors')
meshVTK.addScalarBar(c='k').legend('Found Clusters')
#meshVTK.alpha(0.5) # set transparency

# this line activates and retrieves the array of color numbers:
# (necessary because addScalarBar resets to pointdata)
meshVTK.scalars('CellColors')

meshVTK.show(bg='white', axes=0)

Hope that fits your needs. Remember that:

• you can set colors directly in trimesh and vtkplotter would respect those: see this example.

• you can plot directly any trimesh object by just using vtkplotter.show(mytrimeshobj) without the need of explicitly converting it.

[jrdkr]

Thank you!
I have tried to reproduce your example but always get the following error in actors.py:

meshVTK.cellColors(cols, mode='colors')

File "\vtkplotter\actors.py", line 2315, in cellColors

return self._cellColors1By1(scalars_or_colors, alpha, alphaPerCell)
File "\vtkplotter\actors.py", line 2423, in _cellColors1By1

cellData.InsertNextValue(inds[i])
TypeError: InsertNextValue argument 1: an integer is required

[marcomusy]

thanks @jrdkr I will commit my local version which includes a few fixes asap.

[marcomusy]

@jrdkr you may try to run it again:

git clone https://github.com/marcomusy/vtkplotter.git
cd vtkplotter
pip install .

let me know if it works..

[jrdkr]

@marcomusy
Thanks for uploading your current build. Unfortunately I still get the same error in actors.py line 2421

[jrdkr]

@marcomusy
Thanks for uploading your current build. Unfortunately I still get the same error in actors.py line 2421:

Now its working for me. Thank you.
cellData.InsertNextValue(int(inds[i]))

[marcomusy]

sounds great :)
it's strange that the same error doesn't show up on my system..
i'll add your fix in the next release!
Thanks