Unhandled Rejection (TypeError): Cannot read property 'getRange' of null

hello.

I extracted the vti from the dicom file series using the following Python code:

def vtkImageToNumPy(image, pixelDims):
    imageData = reader.GetOutput()
    pointData = image.GetPointData()
    arrayData = pointData.GetArray(0)
    ArrayDicom = numpy_support.vtk_to_numpy(arrayData)
    ArrayDicom = ArrayDicom.reshape(pixelDims, order='F')

    return ArrayDicom

dicomFolder = "./lung_imgs"
reader = vtk.vtkDICOMImageReader()
reader.SetDirectoryName(dicomFolder)
reader.Update()

# Load dimensions using `GetDataExtent`
my_extent = reader.GetDataExtent()
ConstPixelDims = [my_extent[1]-my_extent[0]+1, my_extent[3]-my_extent[2]+1, my_extent[5]-my_extent[4]+1]

# Load spacing values
ConstPixelSpacing = reader.GetPixelSpacing()

dicom_array = vtkImageToNumPy(reader.GetOutput(), ConstPixelDims)

from pyevtk.hl import imageToVTK

imageToVTK("./lungResult",cellData={"ArrayDicom" : dicom_array})

So I tried to implement volume rendering. However, the following error occurred:

So I tried to compare the implemented vti file with the unimplemented vti file through the para view. There were the following differences:

[unimplemented]

[implemented]

I want to find the difference and solution between the above pictures. I would like to implement volume rendering using ArrayDicom.

I would really appreciate your reply.

[jourdain]

I thing VolumeRendering expect Scalars unless you specify which array you want to look at.

Anyway a way to fix that is to locally set that array as scalars

const pd = imageData.getPointData();
pd.setScalars(pd.getArray(0));

[jourdain]

Probably because you don’t have Scalars (active array). You can try imageData.getPointData().getArray(0) instead of getScalars().