# Support

**URL:** https://discourse.vtk.org/c/support/6.md?page=122

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

**Page:** 123

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## [Can't enter selection mode in a rendered window](https://discourse.vtk.org/t/cant-enter-selection-mode-in-a-rendered-window/3975)

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**Author:** [@beginner](https://discourse.vtk.org/u/beginner)\
**Replies:** 9\
**Last updated:** [September 2, 2020, 9:52pm UTC](https://discourse.vtk.org/t/cant-enter-selection-mode-in-a-rendered-window/3975 "2020-09-02T21:52:12Z")

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Hi everyone! I’m having trouble entering the selection mode in a render window. Do I just click on ‘r’ on my keyboard? I’ve tried that but it doesn’t work. I’m not sure why that is…

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## [WorldPointPicker: get the right value if you zoom in](https://discourse.vtk.org/t/worldpointpicker-get-the-right-value-if-you-zoom-in/4096)

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**Author:** [@tommi](https://discourse.vtk.org/u/tommi)\
**Replies:** 2\
**Last updated:** [September 2, 2020, 11:21am UTC](https://discourse.vtk.org/t/worldpointpicker-get-the-right-value-if-you-zoom-in/4096 "2020-09-02T11:21:14Z")

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I use this example for a WorldPointPicker. It works fine, but if i zoom in, it doesn’t give the correct coordinates. How can i correct this?

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## [Cell Center from GetParametricCenter and EvaluateLocation](https://discourse.vtk.org/t/cell-center-from-getparametriccenter-and-evaluatelocation/4108)

<div class="topic-metadata">

**Author:** [@a-jp1](https://discourse.vtk.org/u/a-jp1)\
**Replies:** 6\
**Last updated:** [September 1, 2020, 1:42pm UTC](https://discourse.vtk.org/t/cell-center-from-getparametriccenter-and-evaluatelocation/4108 "2020-09-01T13:42:03Z")

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Hi, I’m looking for the exact (correct) cell centre for cells of a vtkUnstructuredGrid. Exact (correct) in the sense that it would return the same result as a divergence theorem face-based integration around the faces …

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## [vtkHexahedron node ordering question](https://discourse.vtk.org/t/vtkhexahedron-node-ordering-question/4111)

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**Author:** [@philippeVerney](https://discourse.vtk.org/u/philippeVerney)\
**Replies:** 5\
**Last updated:** [August 31, 2020, 4:27pm UTC](https://discourse.vtk.org/t/vtkhexahedron-node-ordering-question/4111 "2020-08-31T16:27:41Z")

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Hi all, I am looking at VTK conventions for node ordering especially for vtkHexahedron. I am also looking at the VTK documentation stating : The hexahedron is defined by the eight points (0-7) where (0,1,2,3) is the ba…

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## [Interactive text widget. Search box.](https://discourse.vtk.org/t/interactive-text-widget-search-box/4009)

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**Author:** [@phcerdan](https://discourse.vtk.org/u/phcerdan)\
**Replies:** 5\
**Last updated:** [August 31, 2020, 11:31am UTC](https://discourse.vtk.org/t/interactive-text-widget-search-box/4009 "2020-08-31T11:31:06Z")

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I’d like to have a search box in my scene, where the user enters a point id, and that point is highlighted for example. Is there any widget that handles the input of text from the user? I am guessing that a TextWidget c…

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## [VMTK：question about the input of vtkvmtkPolyDataCenterlines](https://discourse.vtk.org/t/vmtk-question-about-the-input-of-vtkvmtkpolydatacenterlines/4088)

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**Author:** [@NeuZhangQiang](https://discourse.vtk.org/u/NeuZhangQiang)\
**Replies:** 1\
**Last updated:** [August 31, 2020, 8:23am UTC](https://discourse.vtk.org/t/vmtk-question-about-the-input-of-vtkvmtkpolydatacenterlines/4088 "2020-08-31T08:23:57Z")

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I need to extract center lines from airway mask, and VMTK is a very good tool. VMTK use vtkvmtkPolyDataCenterlines to extract the center lines, and the usage of vtkvmtkPolyDataCenterlines is: centerlineFilter = vtk…

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## [Scale bars in vtk python](https://discourse.vtk.org/t/scale-bars-in-vtk-python/4094)

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**Author:** [@Olga\_Ridzel](https://discourse.vtk.org/u/Olga_Ridzel)\
**Replies:** 3\
**Last updated:** [August 29, 2020, 4:13pm UTC](https://discourse.vtk.org/t/scale-bars-in-vtk-python/4094 "2020-08-29T16:13:22Z")

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Dear VTK team, I’m looking for a way to add scale bars to the render window both in python and js. An example picture is attached. I used vtkLineSource and vtkVectorText but depending on the image size I render this do…

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## [vtk, SimpleITK and blender](https://discourse.vtk.org/t/vtk-simpleitk-and-blender/4093)

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**Author:** [@Issam\_Dak](https://discourse.vtk.org/u/Issam_Dak)\
**Replies:** 0\
**Last updated:** [August 28, 2020, 2:35pm UTC](https://discourse.vtk.org/t/vtk-simpleitk-and-blender/4093 "2020-08-28T14:35:24Z")

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Hi, i m new to vtk and SimpleITK and i need some help. I m trying to make a blender addon for reading NRRD file exported from 3Dslicer or dicom sequence from user directory The volume will be read using vtk NRRD reader…

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## [How to crop 3D image from a 2D free-hand ROI?](https://discourse.vtk.org/t/how-to-crop-3d-image-from-a-2d-free-hand-roi/2468)

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**Author:** [@zhang-qiang-github](https://discourse.vtk.org/u/zhang-qiang-github)\
**Replies:** 6\
**Last updated:** [August 28, 2020, 5:58am UTC](https://discourse.vtk.org/t/how-to-crop-3d-image-from-a-2d-free-hand-roi/2468 "2020-08-28T05:58:33Z")

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When analysis 3D image data by rendering, some tissue is unconcerned and it would distrub the analysis. Thus, I want to crop the image by a free-hand ROI just like RadiAnt: In the above picture, the green polygon is t…

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## [Attribute data for cell faces of an Unstructured Grid](https://discourse.vtk.org/t/attribute-data-for-cell-faces-of-an-unstructured-grid/4086)

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**Author:** [@mdh](https://discourse.vtk.org/u/mdh)\
**Replies:** 0\
**Last updated:** [August 27, 2020, 8:24pm UTC](https://discourse.vtk.org/t/attribute-data-for-cell-faces-of-an-unstructured-grid/4086 "2020-08-27T20:24:34Z")

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Is there a way to add attribute data to faces of an unstructured grid? I’m trying to solve a problem where I want to add ids to each face of every cell in an unstructured grid and then get the polygonal surfaces from th…

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## [Adding extra padding to a nifti image](https://discourse.vtk.org/t/adding-extra-padding-to-a-nifti-image/4038)

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**Author:** [@isuruwi](https://discourse.vtk.org/u/isuruwi)\
**Replies:** 3\
**Last updated:** [August 27, 2020, 8:53am UTC](https://discourse.vtk.org/t/adding-extra-padding-to-a-nifti-image/4038 "2020-08-27T08:53:48Z")

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I have a nifiti image where the dimension is (200, 200, 320) and what I want to do is that increase the height and width of the image by adding additional padding around it so that finally it contains (512, 512, 320). Is…

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## [Help with building Paraview Glance](https://discourse.vtk.org/t/help-with-building-paraview-glance/4075)

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**Author:** [@Ramu](https://discourse.vtk.org/u/Ramu)\
**Replies:** 4\
**Last updated:** [August 27, 2020, 6:28am UTC](https://discourse.vtk.org/t/help-with-building-paraview-glance/4075 "2020-08-27T06:28:30Z")

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Hello I am trying to build paraview-glance from Kitware/ paraview-glance GitHub repo. It was successful on my personal laptop but unable to do so in my office machine. (I use enterprise registry and they prevent download…

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## [Add temperature attribute using vtkDoubleArray-\>SetArray is not effect the result color](https://discourse.vtk.org/t/add-temperature-attribute-using-vtkdoublearray-setarray-is-not-effect-the-result-color/4045)

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**Author:** [@wanddfly](https://discourse.vtk.org/u/wanddfly)\
**Replies:** 10\
**Last updated:** [August 26, 2020, 10:47pm UTC](https://discourse.vtk.org/t/add-temperature-attribute-using-vtkdoublearray-setarray-is-not-effect-the-result-color/4045 "2020-08-26T22:47:15Z")

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Hi, I am a beginner, when I my vtkUnstructuredGrid object have a attribute temperature, there are 2 methods to put it into vtkUnstructuredGrid object, one is that put 1 by 1 using InsertNextTuple1() , this method work …

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## [vtkPolyDataAlgorithm: how does Update() deal with return value of RequestData()?](https://discourse.vtk.org/t/vtkpolydataalgorithm-how-does-update-deal-with-return-value-of-requestdata/4070)

<div class="topic-metadata">

**Author:** [@Tomasso](https://discourse.vtk.org/u/Tomasso)\
**Replies:** 1\
**Last updated:** [August 26, 2020, 9:01pm UTC](https://discourse.vtk.org/t/vtkpolydataalgorithm-how-does-update-deal-with-return-value-of-requestdata/4070 "2020-08-26T21:01:11Z")

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void vtkPolyDataAlgorithm::Update() calls virtual int vtkPolyDataAlgorithm::RequestData(). MyAlgorithm is a subclass of vtkPolyDataAlgorithm, and overrides virtual int vtkPolyDataAlgorithm::RequestData(). But the Doxygen …

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## [framebuffer has mismatched attachments error when using vtkSobelGradientMagnitudePass and resizing window](https://discourse.vtk.org/t/framebuffer-has-mismatched-attachments-error-when-using-vtksobelgradientmagnitudepass-and-resizing-window/4073)

<div class="topic-metadata">

**Author:** [@rdbrn](https://discourse.vtk.org/u/rdbrn)\
**Replies:** 1\
**Last updated:** [August 26, 2020, 8:56am UTC](https://discourse.vtk.org/t/framebuffer-has-mismatched-attachments-error-when-using-vtksobelgradientmagnitudepass-and-resizing-window/4073 "2020-08-26T08:56:17Z")

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I’m playing a bit with a vtkSobelGradientMagnitudePass pass using python and vtk 9.0.1 on Windows 10. When I resize my window I get the following error: “ERROR: In …\\Rendering\\OpenGL2\\vtkOpenGLFramebufferObject.cxx, …

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## [In parallel environment, can VTK remove the background of rendering?](https://discourse.vtk.org/t/in-parallel-environment-can-vtk-remove-the-background-of-rendering/4034)

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**Author:** [@Pandapan](https://discourse.vtk.org/u/Pandapan)\
**Replies:** 5\
**Last updated:** [August 26, 2020, 6:44am UTC](https://discourse.vtk.org/t/in-parallel-environment-can-vtk-remove-the-background-of-rendering/4034 "2020-08-26T06:44:27Z")

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I am trying to using VTK for parallel rendering. The problem is that the background will cause errors during image composition. For example, I use two processes to render two images (A and B), respectively. When these…

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## [Show directed AND undirected edges on vtkGraphLayoutView](https://discourse.vtk.org/t/show-directed-and-undirected-edges-on-vtkgraphlayoutview/4062)

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**Author:** [@Andreas\_Scalas](https://discourse.vtk.org/u/Andreas_Scalas)\
**Replies:** 0\
**Last updated:** [August 24, 2020, 6:18pm UTC](https://discourse.vtk.org/t/show-directed-and-undirected-edges-on-vtkgraphlayoutview/4062 "2020-08-24T18:18:19Z")

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Hello, I am new to the VTK support forum. If possible, I would like to ask if any of you have ever tried to display a graph with both directed and undirected edges using the vtkGraphLayoutView class. I came out with the …

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## [Convert Vertex and Index Buffers to vtkPolyData for vtkDecimatePro](https://discourse.vtk.org/t/convert-vertex-and-index-buffers-to-vtkpolydata-for-vtkdecimatepro/4057)

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**Author:** [@Robin](https://discourse.vtk.org/u/Robin)\
**Replies:** 1\
**Last updated:** [August 24, 2020, 3:36pm UTC](https://discourse.vtk.org/t/convert-vertex-and-index-buffers-to-vtkpolydata-for-vtkdecimatepro/4057 "2020-08-24T15:36:21Z")

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Hello, I’m trying to decimate a mesh using vtkDecimatePro. The mesh is represented as a vertex list with a list of indices referencing the corresponding vertices. E.g: Vertices: {0f, 0f, 0f}, {1f, 0f, 0f}, {0f, 1f…

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## [World Rotation in 3D](https://discourse.vtk.org/t/world-rotation-in-3d/4020)

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**Author:** [@AlexG](https://discourse.vtk.org/u/AlexG)\
**Replies:** 3\
**Last updated:** [August 24, 2020, 3:04pm UTC](https://discourse.vtk.org/t/world-rotation-in-3d/4020 "2020-08-24T15:04:26Z")

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Hi, I have a question concerning the rotation of the whole VR Environment. With the currently implemented OnPinch() and OnPan() Methods the whole environment can be scaled and moved. Now i want to use the OnRotate() me…

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## [Stack of PNG files to be rendered as 3D](https://discourse.vtk.org/t/stack-of-png-files-to-be-rendered-as-3d/4040)

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**Author:** [@anand](https://discourse.vtk.org/u/anand)\
**Replies:** 6\
**Last updated:** [August 24, 2020, 6:29am UTC](https://discourse.vtk.org/t/stack-of-png-files-to-be-rendered-as-3d/4040 "2020-08-24T06:29:58Z")

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Hi Team, I’m looking for option in C++ example where I can convert stack of 2D images (PNG format) to render 3D object. Any help would be greatly appreciated. Regards, Anand

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## [Install vtk-8.2.0 in ARM64/aarch64](https://discourse.vtk.org/t/install-vtk-8-2-0-in-arm64-aarch64/4051)

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**Author:** [@koilgg](https://discourse.vtk.org/u/koilgg)\
**Replies:** 0\
**Last updated:** [August 23, 2020, 4:00am UTC](https://discourse.vtk.org/t/install-vtk-8-2-0-in-arm64-aarch64/4051 "2020-08-23T04:00:39Z")

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Hello, I am trying to install vtk in my ubuntu(aarch64). I have tried several methods, but they were all failed. 1.I installed miniforge in ubuntu and downloaded the package 'vtk-8.2.0-py36haa4764d\_200.tar.bz2' from ht…

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## [Apply transformation to nifiti image](https://discourse.vtk.org/t/apply-transformation-to-nifiti-image/4017)

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**Author:** [@isuruwi](https://discourse.vtk.org/u/isuruwi)\
**Replies:** 5\
**Last updated:** [August 22, 2020, 7:02pm UTC](https://discourse.vtk.org/t/apply-transformation-to-nifiti-image/4017 "2020-08-22T19:02:47Z")

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I want to apply transformations to a given nifti image. How can I apply such as translate, scale, rotation to that? See below example for further reference. // read nifti image vtkSmartPointer niftiReader = vtkSmartPoi…

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## [undefined reference to 'ZN16QVTKOpenGLWidget'](https://discourse.vtk.org/t/undefined-reference-to-zn16qvtkopenglwidget/4024)

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**Author:** [@Cesar\_Cherre](https://discourse.vtk.org/u/Cesar_Cherre)\
**Replies:** 1\
**Last updated:** [August 22, 2020, 3:02am UTC](https://discourse.vtk.org/t/undefined-reference-to-zn16qvtkopenglwidget/4024 "2020-08-22T03:02:59Z")

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Hi everyone, I have successfully installed VTK with MinGW64, I have imported the .dll and .h into .pro, but when I run a test code I get this: “…mainwindow.cpp:16: error: undefined reference to ‘imp\_\_ZN16QVTKOpenGLWidge…

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## [How to play the animation of GLTF model](https://discourse.vtk.org/t/how-to-play-the-animation-of-gltf-model/3939)

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**Author:** [@yuhuimoon](https://discourse.vtk.org/u/yuhuimoon)\
**Replies:** 7\
**Last updated:** [August 22, 2020, 2:46am UTC](https://discourse.vtk.org/t/how-to-play-the-animation-of-gltf-model/3939 "2020-08-22T02:46:58Z")

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I have load a GLTF with a simple translation animation successfully by vtkGLTFReader int VTK 9.0.1. I want to play the animation. But I fail after using: gltfReader-\>EnableAnimation(0); //0 is the correct animation ind…

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## [How to create and manipulate stuff in vtkContext2D](https://discourse.vtk.org/t/how-to-create-and-manipulate-stuff-in-vtkcontext2d/4037)

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**Author:** [@alejandronespereira](https://discourse.vtk.org/u/alejandronespereira)\
**Replies:** 2\
**Last updated:** [August 21, 2020, 3:59pm UTC](https://discourse.vtk.org/t/how-to-create-and-manipulate-stuff-in-vtkcontext2d/4037 "2020-08-21T15:59:04Z")

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I am drawing a 3D scene and some 2D slices of the scene on separate windows. If I try to render the full scene into a vectorized image with vtkExporterGL2PS, the output comes with invalid utf-8 characters that break the …

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## [vtkPlaneWidget in Qt](https://discourse.vtk.org/t/vtkplanewidget-in-qt/3926)

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**Author:** [@EvanLee](https://discourse.vtk.org/u/EvanLee)\
**Replies:** 3\
**Last updated:** [August 21, 2020, 5:22am UTC](https://discourse.vtk.org/t/vtkplanewidget-in-qt/3926 "2020-08-21T05:22:52Z")

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Hello，I added a vtkPlaneWidget to the qvtkwidget in Qt program, but it report some problem. Could anyone please give solution to me? Thanks

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## [Increase the 3D image dimension](https://discourse.vtk.org/t/increase-the-3d-image-dimension/4019)

<div class="topic-metadata">

**Author:** [@isuruwi](https://discourse.vtk.org/u/isuruwi)\
**Replies:** 4\
**Last updated:** [August 20, 2020, 4:30pm UTC](https://discourse.vtk.org/t/increase-the-3d-image-dimension/4019 "2020-08-20T16:30:31Z")

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I first created a volumetric mesh. Then extract the surface mesh using vtkGeometryFilter and use vtkPolyDataToImageStencil to generate the 3D image. I have got the image dimension as (200, 200, 320). But now I want to in…

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## [vtkSplineWidget2 not pickable or read only](https://discourse.vtk.org/t/vtksplinewidget2-not-pickable-or-read-only/4015)

<div class="topic-metadata">

**Author:** [@flaviu2](https://discourse.vtk.org/u/flaviu2)\
**Replies:** 1\
**Last updated:** [August 20, 2020, 3:58pm UTC](https://discourse.vtk.org/t/vtksplinewidget2-not-pickable-or-read-only/4015 "2020-08-20T15:58:07Z")

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Is there any method to setup vtkSplineWidget2 as not pickable ? I have tried following methods: pSplineRepresentation-\>DragableOff(); pSplineRepresentation-\>ClosedOff(); pSplineRepresentation-\>PickableOff(); However…

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## [installing vtk \> 8.2 for python 3.7.3 no attributes available](https://discourse.vtk.org/t/installing-vtk-8-2-for-python-3-7-3-no-attributes-available/3821)

<div class="topic-metadata">

**Author:** [@Kevin\_Johnson](https://discourse.vtk.org/u/Kevin_Johnson)\
**Replies:** 5\
**Last updated:** [August 20, 2020, 3:37pm UTC](https://discourse.vtk.org/t/installing-vtk-8-2-for-python-3-7-3-no-attributes-available/3821 "2020-08-20T15:37:45Z")

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I am trying to use VTK on a machine with ubuntu 16.04 and python 3.7.3 running Anaconda 2019.03. Anaconda installed vtk 8.2.0. I import vtk and type “vtk.” and the auto field only shows 9 options but is missing many im…

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## [Is it possible to change lines join type](https://discourse.vtk.org/t/is-it-possible-to-change-lines-join-type/4008)

<div class="topic-metadata">

**Author:** [@embeddedmz](https://discourse.vtk.org/u/embeddedmz)\
**Replies:** 2\
**Last updated:** [August 20, 2020, 8:12am UTC](https://discourse.vtk.org/t/is-it-possible-to-change-lines-join-type/4008 "2020-08-20T08:12:17Z")

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Hi everyone, The title says it all. Take this example : https://lorensen.github.io/VTKExamples/site/Cxx/GeometricObjects/PolyLine/ and insert this line of code after line 68 actor-\>GetProperty()-\>SetLineWidth(14); Bui…

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