'vtkDICOMImageReader' Errors: 'Couldn't get sorted files', while trying to import a set of .dcm files.

Hello All,
I am trying to run the following example from MedicalDemo4 using Python3.

Since my input data is a set of raw CT images, I modified ‘reader = vtkMetaImageReader()’ to ‘reader = vtkDICOMImageReader()’ with ‘reader.SetDirectory(file_name)’ for reading the .dcm files.

# noinspection PyUnresolvedReferences
import vtkmodules.vtkInteractionStyle
# noinspection PyUnresolvedReferences
import vtkmodules.vtkRenderingOpenGL2
# noinspection PyUnresolvedReferences
import vtkmodules.vtkRenderingVolumeOpenGL2
from vtkmodules.vtkCommonColor import vtkNamedColors
from vtkmodules.vtkCommonDataModel import vtkPiecewiseFunction
from vtkmodules.vtkIOImage import vtkMetaImageReader, vtkNIFTIImageReader, vtkDICOMImageReader
from vtkmodules.vtkRenderingCore import (
from vtkmodules.vtkRenderingVolume import vtkFixedPointVolumeRayCastMapper, vtkGPUVolumeRayCastMapper

def main():
    colors = vtkNamedColors()

    file_name = "C:\\Data\\export\\11732786-20220922-5"

    colors.SetColor('BkgColor', [51, 77, 102, 255])

    # Create the renderer, the render window, and the interactor. The renderer
    # draws into the render window, the interactor enables mouse- and
    # keyboard-based interaction with the scene.
    ren = vtkRenderer()
    ren_win = vtkRenderWindow()
    iren = vtkRenderWindowInteractor()

    # The following reader is used to read a series of 2D slices (images)
    # that compose the volume. The slice dimensions are set, and the
    # pixel spacing. The data Endianness must also be specified. The reader
    # uses the FilePrefix in combination with the slice number to construct
    # filenames using the format FilePrefix.%d. (In this case the FilePrefix
    # is the root name of the file: quarter.)
    # reader = vtkMetaImageReader()
    # reader = vtkNIFTIImageReader()
    reader = vtkDICOMImageReader()
    # reader.SetFileName(file_name)

    # The volume will be displayed by ray-cast alpha compositing.
    # A ray-cast mapper is needed to do the ray-casting.
    # volume_mapper = vtkFixedPointVolumeRayCastMapper()
    volume_mapper = vtkGPUVolumeRayCastMapper()

    # The color transfer function maps voxel intensities to colors.
    # It is modality-specific, and often anatomy-specific as well.
    # The goal is to one color for flesh (between 500 and 1000)
    # and another color for bone (1150 and over).
    volume_color = vtkColorTransferFunction()
    volume_color.AddRGBPoint(0, 0.0, 0.0, 0.0)
    volume_color.AddRGBPoint(500, 240.0 / 255.0, 184.0 / 255.0, 160.0 / 255.0)
    volume_color.AddRGBPoint(1000, 240.0 / 255.0, 184.0 / 255.0, 160.0 / 255.0)
    volume_color.AddRGBPoint(1150, 1.0, 1.0, 240.0 / 255.0)  # Ivory

    # The opacity transfer function is used to control the opacity
    # of different tissue types.
    volume_scalar_opacity = vtkPiecewiseFunction()
    volume_scalar_opacity.AddPoint(0, 0.00)
    volume_scalar_opacity.AddPoint(500, 0.15)
    volume_scalar_opacity.AddPoint(1000, 0.15)
    volume_scalar_opacity.AddPoint(1150, 0.85)

    # The gradient opacity function is used to decrease the opacity
    # in the 'flat' regions of the volume while maintaining the opacity
    # at the boundaries between tissue types.  The gradient is measured
    # as the amount by which the intensity changes over unit distance.
    # For most medical data, the unit distance is 1mm.
    volume_gradient_opacity = vtkPiecewiseFunction()
    volume_gradient_opacity.AddPoint(0, 0.0)
    volume_gradient_opacity.AddPoint(90, 0.5)
    volume_gradient_opacity.AddPoint(100, 1.0)

    # The VolumeProperty attaches the color and opacity functions to the
    # volume, and sets other volume properties.  The interpolation should
    # be set to linear to do a high-quality rendering.  The ShadeOn option
    # turns on directional lighting, which will usually enhance the
    # appearance of the volume and make it look more '3D'.  However,
    # the quality of the shading depends on how accurately the gradient
    # of the volume can be calculated, and for noisy data the gradient
    # estimation will be very poor.  The impact of the shading can be
    # decreased by increasing the Ambient coefficient while decreasing
    # the Diffuse and Specular coefficient.  To increase the impact
    # of shading, decrease the Ambient and increase the Diffuse and Specular.
    volume_property = vtkVolumeProperty()

    # The vtkVolume is a vtkProp3D (like a vtkActor) and controls the position
    # and orientation of the volume in world coordinates.
    volume = vtkVolume()

    # Finally, add the volume to the renderer

    # Set up an initial view of the volume.  The focal point will be the
    # center of the volume, and the camera position will be 400mm to the
    # patient's left (which is our right).
    camera = ren.GetActiveCamera()
    c = volume.GetCenter()
    camera.SetViewUp(0, 0, -1)
    camera.SetPosition(c[0], c[1] - 400, c[2])
    camera.SetFocalPoint(c[0], c[1], c[2])

    # Set a background color for the renderer

    # Increase the size of the render window
    ren_win.SetSize(640, 480)

    # Interact with the data.

# def get_program_parameters():
#     import argparse
#     description = 'Read a volume dataset and displays it via volume rendering.'
#     epilogue = '''
#     Derived from VTK/Examples/Cxx/Medical4.cxx
#     '''
#     parser = argparse.ArgumentParser(description=description, epilog=epilogue,
#                                      formatter_class=argparse.RawDescriptionHelpFormatter)
#     parser.add_argument('filename', help='FullHead.mhd.')
#     args = parser.parse_args()
#     return args.filename

if __name__ == '__main__':

and I got the following errors

vtkDICOMImageReader.cxx:224    ERR| vtkDICOMImageReader (0000020DEE515C90): Couldn't get sorted files. Slices may be in wrong order!
vtkDICOMImageReader.cxx:302    ERR| vtkDICOMImageReader (0000020DEE515C90): No memory allocated for image data!
vtkVolumeTexture.cxx:950    ERR| vtkVolumeTexture (0000020DF1C1CA10): Capabilities check via proxy texture 3D allocation failed!

To verify the correctness of the code, I got the desired rendering images with importing Visible Human Data, didn’t encounter the above errors.

No modifications were made to my private dataset and I have no doubt that they are in the correct order from CT scanner.

I do not know what kind of order is recognized by ‘vtkDICOMImageReader’?
I am not sure how to fix those errors.
Suggestions will be really helpful.


The lowest level error (thrown by a vtkVolumeTexture) suggests a limitation or something wrong in the graphics backend (graphics card driver or graphics hardware).

Have you tried to render a small volume (say 20x20x20)?