# Support

**URL:** https://discourse.vtk.org/c/support/6.md?page=111

[Latest](https://discourse.vtk.org/latest.md) · [Categories](https://discourse.vtk.org/categories.md) · [Tags](https://discourse.vtk.org/tags.md)

**Page:** 112

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## [Following the mouse coordinates in Z when I drag a line in space](https://discourse.vtk.org/t/following-the-mouse-coordinates-in-z-when-i-drag-a-line-in-space/5175)

<div class="topic-metadata">

**Author:** [@zandarina](https://discourse.vtk.org/u/zandarina)\
**Replies:** 0\
**Last updated:** [February 12, 2021, 8:17am UTC](https://discourse.vtk.org/t/following-the-mouse-coordinates-in-z-when-i-drag-a-line-in-space/5175 "2021-02-12T08:17:22Z")

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Hello, I am trying to program a gizmo with translation what I want is from the point I click on an axis (point of a line) to keep the same position while I drag the line while I move the mouse. The problem comes with Z …

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## [Can I display different boxwidgets in different render?](https://discourse.vtk.org/t/can-i-display-different-boxwidgets-in-different-render/5171)

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**Author:** [@timeanddoctor](https://discourse.vtk.org/u/timeanddoctor)\
**Replies:** 0\
**Last updated:** [February 11, 2021, 6:17am UTC](https://discourse.vtk.org/t/can-i-display-different-boxwidgets-in-different-render/5171 "2021-02-11T06:17:04Z")

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How can I display different boxwidgets in different render? boxWidget2.SetProp3D(selectActor) boxWidget2.PlaceWidget() boxWidget2.On() boxWidget2.AddObserver(“InteractionEvent”, TransformActor) ren2.AddViewProp(boxW…

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## [Turn off arrow for vtkImplicitPlaneWidget](https://discourse.vtk.org/t/turn-off-arrow-for-vtkimplicitplanewidget/1925)

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**Author:** [@banesullivan](https://discourse.vtk.org/u/banesullivan)\
**Replies:** 2\
**Last updated:** [February 10, 2021, 6:12pm UTC](https://discourse.vtk.org/t/turn-off-arrow-for-vtkimplicitplanewidget/1925 "2021-02-10T18:12:59Z")

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Is it possible to turn off the normal vector/arrow for the vtk.vtkImplicitPlaneWidget class? I’d like to have a plane widget that is set to be orthogonal to an axis and I don’t want to accidentally click the arrow to rot…

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## [How to calculate the cross point between line and mask](https://discourse.vtk.org/t/how-to-calculate-the-cross-point-between-line-and-mask/5159)

<div class="topic-metadata">

**Author:** [@zhang-qiang-github](https://discourse.vtk.org/u/zhang-qiang-github)\
**Replies:** 5\
**Last updated:** [February 10, 2021, 12:58pm UTC](https://discourse.vtk.org/t/how-to-calculate-the-cross-point-between-line-and-mask/5159 "2021-02-10T12:58:21Z")

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For a line, it will intersect with mask for several points, then I want to calculate the intersection point. For example: mask = np.zeros(\[300, 300, 50\]) mask\[:, :, 10:30\] = 1 Then, the line is: p1 = \[100, 100, -1\] …

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## [Cut of AMR dataset](https://discourse.vtk.org/t/cut-of-amr-dataset/5162)

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**Author:** [@hakostra](https://discourse.vtk.org/u/hakostra)\
**Replies:** 0\
**Last updated:** [February 9, 2021, 2:22pm UTC](https://discourse.vtk.org/t/cut-of-amr-dataset/5162 "2021-02-09T14:22:22Z")

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I have a simulation code that write out an hierarchical octree grid structure. The coarsest level is filled, and then comes finer levels on top where refinement is needed. Each level is built of small Cartesian grids of …

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## [VTK manipulation of image in memory.](https://discourse.vtk.org/t/vtk-manipulation-of-image-in-memory/5157)

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**Author:** [@Luis\_Carlos\_Carneiro](https://discourse.vtk.org/u/Luis_Carlos_Carneiro)\
**Replies:** 3\
**Last updated:** [February 8, 2021, 9:44pm UTC](https://discourse.vtk.org/t/vtk-manipulation-of-image-in-memory/5157 "2021-02-08T21:44:08Z")

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Dear All, I have a 3D .mhd file. Then I visualize that file with VTK. I determine a region of that image to crop. How I reflect the crop in the visualization. Have I to crop the .mhd image in memory and redisplay? Are…

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## [How to represent multiple actors with one single actor?](https://discourse.vtk.org/t/how-to-represent-multiple-actors-with-one-single-actor/5150)

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**Author:** [@11114](https://discourse.vtk.org/u/11114)\
**Replies:** 4\
**Last updated:** [February 8, 2021, 2:41pm UTC](https://discourse.vtk.org/t/how-to-represent-multiple-actors-with-one-single-actor/5150 "2021-02-08T14:41:23Z")

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my problem is I have got a 3D hammer model that formed by multiple cells which means multiple actors and mappers should be present in the scene , so is there any way I can make these hammer represent by a single actor(i.…

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## [Learning VTK, with a 3D graphics geometry mindset](https://discourse.vtk.org/t/learning-vtk-with-a-3d-graphics-geometry-mindset/2130)

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**Author:** [@cesss](https://discourse.vtk.org/u/cesss)\
**Replies:** 9\
**Last updated:** [February 6, 2021, 10:52pm UTC](https://discourse.vtk.org/t/learning-vtk-with-a-3d-graphics-geometry-mindset/2130 "2021-02-06T22:52:09Z")

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Hi! I’m struggling to understand both the Textbook and the User’s Guide PDFs, because my knowledge is very heavily 3D CG-focused (you know: mesh data, mesh animation, lighting/materials, etc), and while these two books …

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## [Two overlapping vtkPolyData render flashes](https://discourse.vtk.org/t/two-overlapping-vtkpolydata-render-flashes/5136)

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**Author:** [@Lisa](https://discourse.vtk.org/u/Lisa)\
**Replies:** 1\
**Last updated:** [February 5, 2021, 2:45pm UTC](https://discourse.vtk.org/t/two-overlapping-vtkpolydata-render-flashes/5136 "2021-02-05T14:45:36Z")

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Hi everybody, I would like to render two overlapping vtkPolyData using two different color(white and yellow) maps in the same renderer. i want to show yellow vtkPolyData. but, The result is as shown in the figure. what …

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## [Issue with import vtk in Python](https://discourse.vtk.org/t/issue-with-import-vtk-in-python/5133)

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**Author:** [@IVarha](https://discourse.vtk.org/u/IVarha)\
**Replies:** 1\
**Last updated:** [February 3, 2021, 3:35pm UTC](https://discourse.vtk.org/t/issue-with-import-vtk-in-python/5133 "2021-02-03T15:35:13Z")

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Hello VTK community I receive vtk import error in python when I trying to import vtk Traceback (most recent call last): File “/home/varga/venvs/pystn/lib/python3.7/site-packages/vtkmodules/init.py”, line 13, in from …

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## [crush issue vtk python on google colab](https://discourse.vtk.org/t/crush-issue-vtk-python-on-google-colab/5125)

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**Author:** [@COK](https://discourse.vtk.org/u/COK)\
**Replies:** 3\
**Last updated:** [February 3, 2021, 2:43pm UTC](https://discourse.vtk.org/t/crush-issue-vtk-python-on-google-colab/5125 "2021-02-03T14:43:35Z")

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Hello everyone I am trying to use vtk in google colab My tests with simplest vtk code such as circle is returning the crush of kernel each time with an unknown error. I traced back the line that the code crushes with …

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## [vtkCelllocator slow in the version VTK 9 than VTK 8](https://discourse.vtk.org/t/vtkcelllocator-slow-in-the-version-vtk-9-than-vtk-8/5068)

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**Author:** [@Ahmed](https://discourse.vtk.org/u/Ahmed)\
**Replies:** 6\
**Last updated:** [February 3, 2021, 1:41pm UTC](https://discourse.vtk.org/t/vtkcelllocator-slow-in-the-version-vtk-9-than-vtk-8/5068 "2021-02-03T13:41:04Z")

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Hi, I compare the performance of vtkCelllocator in vtk 9 compared to the VTK 8, I use FindClosestPoint method I find that the VTK 9 is 2x more slow than VTK 8 Did some people identify the same problem ? What is the so…

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## [Get normals coordinates](https://discourse.vtk.org/t/get-normals-coordinates/5124)

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**Author:** [@Anastasiia](https://discourse.vtk.org/u/Anastasiia)\
**Replies:** 4\
**Last updated:** [February 3, 2021, 11:35am UTC](https://discourse.vtk.org/t/get-normals-coordinates/5124 "2021-02-03T11:35:14Z")

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Hi VTK community, Is there any options to get X,Y,Z coordinates of the cell normals? Currently I have the following code: normals = vtk.vtkPPolyDataNormals() normals.SetInputConnection(decimate.GetOutputPort()) norm…

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## [Hidden edges are visible on VTK 9.0.0](https://discourse.vtk.org/t/hidden-edges-are-visible-on-vtk-9-0-0/5112)

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**Author:** [@Flagada](https://discourse.vtk.org/u/Flagada)\
**Replies:** 5\
**Last updated:** [February 3, 2021, 9:35am UTC](https://discourse.vtk.org/t/hidden-edges-are-visible-on-vtk-9-0-0/5112 "2021-02-03T09:35:32Z")

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Hi all! I have recently encountered a problem when updating my code from VTK 8 to VTK 9 on my python/qt5/vtk app. The only change in my installation is an update from VTK 8.1.2 to VTK 9.0.0 and this is the strange beha…

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## [Assigning a particular vector array result to VTKStreamTracer](https://discourse.vtk.org/t/assigning-a-particular-vector-array-result-to-vtkstreamtracer/5110)

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**Author:** [@Swarna\_Ravali](https://discourse.vtk.org/u/Swarna_Ravali)\
**Replies:** 0\
**Last updated:** [February 1, 2021, 10:46am UTC](https://discourse.vtk.org/t/assigning-a-particular-vector-array-result-to-vtkstreamtracer/5110 "2021-02-01T10:46:11Z")

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Hi, Mainly VTKStreamTracer takes InputData and SourceConnection to plot the flowlines. In my scenario, I have vtkUnstructuredgrid with various vector array results. My query is that, how can we assign a particular vecto…

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## [Unknown CMake command "vtk\_module\_config"](https://discourse.vtk.org/t/unknown-cmake-command-vtk-module-config/1295)

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**Author:** [@Rogermc](https://discourse.vtk.org/u/Rogermc)\
**Replies:** 3\
**Last updated:** [February 1, 2021, 7:09am UTC](https://discourse.vtk.org/t/unknown-cmake-command-vtk-module-config/1295 "2021-02-01T07:09:45Z")

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Mac-Mini 2018 OSX 10.14.15 XCode 10.2.1 VTK Latest git pull origin master I tried to build Examples/Tutorial/Step1/Cxx but Cmake Configure fails with: CMake Error at CMakeLists.txt:7 (vtk\_module\_config): Unknown C…

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## [get centroids in python script](https://discourse.vtk.org/t/get-centroids-in-python-script/5073)

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**Author:** [@Marco\_De\_Pietri](https://discourse.vtk.org/u/Marco_De_Pietri)\
**Replies:** 10\
**Last updated:** [January 30, 2021, 3:35pm UTC](https://discourse.vtk.org/t/get-centroids-in-python-script/5073 "2021-01-30T15:35:18Z")

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Hi I am trying to extract the centroids of an unstructured mesh in a python script. Sorry if it is a noob question, as I am an not an expert with the vtk module. My understanding is that the vtk classes and its public me…

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## [Looking for a Python VTK equivalent to Matlab's Isosurface function](https://discourse.vtk.org/t/looking-for-a-python-vtk-equivalent-to-matlabs-isosurface-function/5087)

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**Author:** [@Vardonir](https://discourse.vtk.org/u/Vardonir)\
**Replies:** 6\
**Last updated:** [January 30, 2021, 12:33pm UTC](https://discourse.vtk.org/t/looking-for-a-python-vtk-equivalent-to-matlabs-isosurface-function/5087 "2021-01-30T12:33:54Z")

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I have the data as a (n\_x\*n\_y\*n\_z) array in Matlab, which I can easily transfer over to numpy using scipy.io. My code so far looks like this: frommat = loadmat("thefile.mat") the3d = frommat\["appropriate heade…

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## [Thickness or Depth of a polydata along a direction](https://discourse.vtk.org/t/thickness-or-depth-of-a-polydata-along-a-direction/5076)

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**Author:** [@DFlyer](https://discourse.vtk.org/u/DFlyer)\
**Replies:** 6\
**Last updated:** [January 29, 2021, 6:53am UTC](https://discourse.vtk.org/t/thickness-or-depth-of-a-polydata-along-a-direction/5076 "2021-01-29T06:53:36Z")

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Hello, I am trying to scalar plot thickness ( or depth ) of a water tight polydata along a direction. Currently I create a line from a point on polydata and perform vtkOBBTree -\> IntersectWithLine, get the distance bet…

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## [Help!I need compiled qt5.15+VTK8.2+DEBUG (means the compiled version is VTK8.2 +DEBUG and support QT5.15 development, )](https://discourse.vtk.org/t/help-i-need-compiled-qt5-15-vtk8-2-debug-means-the-compiled-version-is-vtk8-2-debug-and-support-qt5-15-development/4965)

<div class="topic-metadata">

**Author:** [@Riton](https://discourse.vtk.org/u/Riton)\
**Replies:** 13\
**Last updated:** [January 29, 2021, 6:26am UTC](https://discourse.vtk.org/t/help-i-need-compiled-qt5-15-vtk8-2-debug-means-the-compiled-version-is-vtk8-2-debug-and-support-qt5-15-development/4965 "2021-01-29T06:26:06Z")

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I have qt5.15+VTK9.0+DEBUG,but the functions do not work right.And I also have qt5.15+VTK8.2+RELEASE,then the functions work right.But when I compiled qt5.15+VTK8.2+DEBUG by myself,it always failed.So who can give me th…

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## [Comparing DRR with x-ray image](https://discourse.vtk.org/t/comparing-drr-with-x-ray-image/5075)

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**Author:** [@tzodge](https://discourse.vtk.org/u/tzodge)\
**Replies:** 1\
**Last updated:** [January 28, 2021, 3:28am UTC](https://discourse.vtk.org/t/comparing-drr-with-x-ray-image/5075 "2021-01-28T03:28:56Z")

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I want to compare a DRR of a CT scan with an Xray. Is there any way that I can find an optimal transfer function using VTK ? Thanks

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## [How to blend a gray and rgb image?](https://discourse.vtk.org/t/how-to-blend-a-gray-and-rgb-image/5072)

<div class="topic-metadata">

**Author:** [@zhang-qiang-github](https://discourse.vtk.org/u/zhang-qiang-github)\
**Replies:** 2\
**Last updated:** [January 28, 2021, 12:23am UTC](https://discourse.vtk.org/t/how-to-blend-a-gray-and-rgb-image/5072 "2021-01-28T00:23:55Z")

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I need to blend a gray and rgb image, and my code is: import vtk import numpy as np from vtk.util.numpy\_support import vtk\_to\_numpy, numpy\_to\_vtk def numpyToVTK(data, multi\_component=False): if multi\_component == …

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## [How to avoid the sawtooth from vtkImageReslice?](https://discourse.vtk.org/t/how-to-avoid-the-sawtooth-from-vtkimagereslice/5023)

<div class="topic-metadata">

**Author:** [@zhang-qiang-github](https://discourse.vtk.org/u/zhang-qiang-github)\
**Replies:** 3\
**Last updated:** [January 27, 2021, 2:54pm UTC](https://discourse.vtk.org/t/how-to-avoid-the-sawtooth-from-vtkimagereslice/5023 "2021-01-27T14:54:53Z")

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I find there is sawtooth for the output of vtkImageReslice, how can I avoid this sawtooth? Any suggestion is appreciated!

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## [Cannot use QVTKRenderWindowInteractor and QWebEngineView together in one application.](https://discourse.vtk.org/t/cannot-use-qvtkrenderwindowinteractor-and-qwebengineview-together-in-one-application/5059)

<div class="topic-metadata">

**Author:** [@sherinnovation](https://discourse.vtk.org/u/sherinnovation)\
**Replies:** 3\
**Last updated:** [January 26, 2021, 9:06pm UTC](https://discourse.vtk.org/t/cannot-use-qvtkrenderwindowinteractor-and-qwebengineview-together-in-one-application/5059 "2021-01-26T21:06:12Z")

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When I use QVTKRenderWindowInteractor and QWebEngineView together in my PyQt source running under Windows 10, I get the following error whenever I close the application window. vtkWin32OpenGLRenderWin:217 ERR| vtkWi…

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## [Is there a way to get the raw data array in vtkDataArray by zero-copy ?](https://discourse.vtk.org/t/is-there-a-way-to-get-the-raw-data-array-in-vtkdataarray-by-zero-copy/5061)

<div class="topic-metadata">

**Author:** [@1116](https://discourse.vtk.org/u/1116)\
**Replies:** 4\
**Last updated:** [January 27, 2021, 2:12am UTC](https://discourse.vtk.org/t/is-there-a-way-to-get-the-raw-data-array-in-vtkdataarray-by-zero-copy/5061 "2021-01-27T02:12:36Z")

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Hello, I try to get the offsetArray and the connectivityArray from the cellArray, and then transfer them to other program for further processing. I noticed that the return value of GetConnectivityArray() function is vtk…

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## [Splitting cells on a PolyData](https://discourse.vtk.org/t/splitting-cells-on-a-polydata/5021)

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**Author:** [@whophil](https://discourse.vtk.org/u/whophil)\
**Replies:** 8\
**Last updated:** [January 26, 2021, 4:07pm UTC](https://discourse.vtk.org/t/splitting-cells-on-a-polydata/5021 "2021-01-26T16:07:57Z")

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I’d like to “split” cells on a PolyData surface, adding vertices and cells. For example, in the screenshot below, I am starting with the black mesh, and I’d like to add all the points where the pink lines intersect the m…

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## [vtkMultiVolume - Clipping plane implemented?](https://discourse.vtk.org/t/vtkmultivolume-clipping-plane-implemented/5056)

<div class="topic-metadata">

**Author:** [@tchen87](https://discourse.vtk.org/u/tchen87)\
**Replies:** 2\
**Last updated:** [January 26, 2021, 4:08pm UTC](https://discourse.vtk.org/t/vtkmultivolume-clipping-plane-implemented/5056 "2021-01-26T16:08:16Z")

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I have been playing around with vtkMultiVolume, and I have not been able to apply clipping planes successfully to the actor. Am I missing something or have clipping planes not been implemented for this feature yet?

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## [Using QVTKOpenGLNativeWidget in PyQt](https://discourse.vtk.org/t/using-qvtkopenglnativewidget-in-pyqt/5058)

<div class="topic-metadata">

**Author:** [@sherinnovation](https://discourse.vtk.org/u/sherinnovation)\
**Replies:** 0\
**Last updated:** [January 26, 2021, 11:33am UTC](https://discourse.vtk.org/t/using-qvtkopenglnativewidget-in-pyqt/5058 "2021-01-26T11:33:39Z")

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I would like to use the class QVTKOpenGLNativeWidget in my PyQt application as I am facing problems with my existing QVTKRenderWindowInteractor class when used along with QWebEngineView Does anyone know how to import th…

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## [Read sequence picture with different position](https://discourse.vtk.org/t/read-sequence-picture-with-different-position/5015)

<div class="topic-metadata">

**Author:** [@shan\_tong](https://discourse.vtk.org/u/shan_tong)\
**Replies:** 1\
**Last updated:** [January 26, 2021, 1:41am UTC](https://discourse.vtk.org/t/read-sequence-picture-with-different-position/5015 "2021-01-26T01:41:46Z")

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Hi when I read sequence picture with different position I have a problem. My sequence images are randomly collected images, so the coordinates are not continuous in one direction like CT images. How should I read my im…

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## [how does vtkIdType work?](https://discourse.vtk.org/t/how-does-vtkidtype-work/5024)

<div class="topic-metadata">

**Author:** [@1116](https://discourse.vtk.org/u/1116)\
**Replies:** 4\
**Last updated:** [January 23, 2021, 11:05am UTC](https://discourse.vtk.org/t/how-does-vtkidtype-work/5024 "2021-01-23T11:05:54Z")

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It looks that vtkIdType can be an integer type with the 32bit or 64bit based on runtime information (https://vtk.org/doc/release/4.2/html/classvtkIdType.html), I’m curious how it works, where it is defined, and what are …

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