# Latest

**URL:** https://discourse.vtk.org/latest.md?page=230

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

**Page:** 231

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## [after rotate the reslicecursor, how to get the slice count?](https://discourse.vtk.org/t/after-rotate-the-reslicecursor-how-to-get-the-slice-count/1622)

<div class="topic-metadata">

**Author:** [@pingdan](https://discourse.vtk.org/u/pingdan)\
**Replies:** 10\
**Last updated:** [December 9, 2019, 6:44pm UTC](https://discourse.vtk.org/t/after-rotate-the-reslicecursor-how-to-get-the-slice-count/1622 "2019-12-09T18:44:19Z")

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vtkImagePlaneWidget,vtkResliceCursorWidget,vtkResliceCursor,vtkResliceCursorThickLineRepresentation I use these classes to display MPR.when I rotate the reslicecursor with the mouse, we can the see the reslicecursor rot…

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## [Switching between renderers in vtkRenderWindow](https://discourse.vtk.org/t/switching-between-renderers-in-vtkrenderwindow/2234)

<div class="topic-metadata">

**Author:** [@sboogert](https://discourse.vtk.org/u/sboogert)\
**Replies:** 1\
**Last updated:** [December 9, 2019, 6:40pm UTC](https://discourse.vtk.org/t/switching-between-renderers-in-vtkrenderwindow/2234 "2019-12-09T18:40:18Z")

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So I have an application where I have multiple vtkRenderers which I would like to quickly switch between in my vtkRenderWindow. The vtkRenderWindow appears to keep a collection of renderers, are all of these supposed to …

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## [VTK Scene Graph](https://discourse.vtk.org/t/vtk-scene-graph/2214)

<div class="topic-metadata">

**Author:** [@RJP](https://discourse.vtk.org/u/RJP)\
**Replies:** 5\
**Last updated:** [December 9, 2019, 3:26pm UTC](https://discourse.vtk.org/t/vtk-scene-graph/2214 "2019-12-09T15:26:14Z")

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Hi all, After years of using VTK, there’s one thing that’s been bothering us and we don’t know how to solve it yet: We want to have a Scene Graph in VTK that can be shared across multiple renderwindows. We noticed tha…

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## [2D Triangle intersection](https://discourse.vtk.org/t/2d-triangle-intersection/2230)

<div class="topic-metadata">

**Author:** [@marcomusy](https://discourse.vtk.org/u/marcomusy)\
**Replies:** 0\
**Last updated:** [December 8, 2019, 2:04am UTC](https://discourse.vtk.org/t/2d-triangle-intersection/2230 "2019-12-08T02:04:54Z")

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I wonder if there is a way of finding the overlapping area of two arbitrary triangles in 2D. I could only come up with the idea of extruding the 2 triangles (vtkRotationalExtrusionFilter) and find the intersection with v…

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## [Display the mesh of vtk.vtkSphereSource ()](https://discourse.vtk.org/t/display-the-mesh-of-vtk-vtkspheresource/2221)

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**Author:** [@minmin](https://discourse.vtk.org/u/minmin)\
**Replies:** 1\
**Last updated:** [December 6, 2019, 7:24am UTC](https://discourse.vtk.org/t/display-the-mesh-of-vtk-vtkspheresource/2221 "2019-12-06T07:24:35Z")

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I can display the surface, but how can I display it in wireframe? Thank you.

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## [How to use VTK](https://discourse.vtk.org/t/how-to-use-vtk/2212)

<div class="topic-metadata">

**Author:** [@minmin](https://discourse.vtk.org/u/minmin)\
**Replies:** 0\
**Last updated:** [December 5, 2019, 8:03am UTC](https://discourse.vtk.org/t/how-to-use-vtk/2212 "2019-12-05T08:03:03Z")

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Sorry for the amateur question. I want to use vtkSelectEnclosedPoints. Even if you look at https://vtk.org/doc/nightly/html/classvtkSelectEnclosedPoints.html, it is not easy to understand. Are there any examples of Sphe…

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## [compute tangents and normal planes of a curve](https://discourse.vtk.org/t/compute-tangents-and-normal-planes-of-a-curve/902)

<div class="topic-metadata">

**Author:** [@cyanxwh](https://discourse.vtk.org/u/cyanxwh)\
**Replies:** 2\
**Last updated:** [December 5, 2019, 1:37am UTC](https://discourse.vtk.org/t/compute-tangents-and-normal-planes-of-a-curve/902 "2019-12-05T01:37:57Z")

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Hi guys, I wonder how to compute the tangents and normal planes of a curve at a point on it using VTK. I have searched it on the Internet but cannot get a clear answer. Can anyone help me? Thanks.

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## [How to do boolean operation on vtkPolyData?](https://discourse.vtk.org/t/how-to-do-boolean-operation-on-vtkpolydata/2208)

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**Author:** [@tianaik](https://discourse.vtk.org/u/tianaik)\
**Replies:** 0\
**Last updated:** [December 5, 2019, 1:28am UTC](https://discourse.vtk.org/t/how-to-do-boolean-operation-on-vtkpolydata/2208 "2019-12-05T01:28:44Z")

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Hi all, I would like to select a part of polydata with vtkInteractorStyleRubberBandPick, and I have realized it with vtkSelection and vtkSelectionNode. Here is the picture And I would like to select another part of p…

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## [How to save the vtkPoints to CSV file format?](https://discourse.vtk.org/t/how-to-save-the-vtkpoints-to-csv-file-format/2115)

<div class="topic-metadata">

**Author:** [@Kim\_William](https://discourse.vtk.org/u/Kim_William)\
**Replies:** 6\
**Last updated:** [December 4, 2019, 2:14am UTC](https://discourse.vtk.org/t/how-to-save-the-vtkpoints-to-csv-file-format/2115 "2019-12-04T02:14:23Z")

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Hi all :slight\_smile: I have a question about vtkPoints to CSV file format. My code is: vtkNew m\_vtkPLYReader; vtkNew m\_vtkPCDPoints; m\_vtkPLYReader-\>SetFileName(path.c\_str()); // Load ply file m\_vtkPLYReader-\>Updat…

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## [How can I extract a polygon with the same shape as a 3d glyph?](https://discourse.vtk.org/t/how-can-i-extract-a-polygon-with-the-same-shape-as-a-3d-glyph/2205)

<div class="topic-metadata">

**Author:** [@rjsgml5698](https://discourse.vtk.org/u/rjsgml5698)\
**Replies:** 0\
**Last updated:** [December 4, 2019, 2:09am UTC](https://discourse.vtk.org/t/how-can-i-extract-a-polygon-with-the-same-shape-as-a-3d-glyph/2205 "2019-12-04T02:09:12Z")

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I tried running the vtp example via the following link. https://vtk.org/Wiki/VTK/Examples/Cxx/IO/WriteVTP However, paraview of the output of .vtp shows 3d glyphs. But points and the surface seem to be completely differ…

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## [How to tell if vtkCutter is empty?](https://discourse.vtk.org/t/how-to-tell-if-vtkcutter-is-empty/2203)

<div class="topic-metadata">

**Author:** [@msmerps](https://discourse.vtk.org/u/msmerps)\
**Replies:** 0\
**Last updated:** [December 3, 2019, 6:20pm UTC](https://discourse.vtk.org/t/how-to-tell-if-vtkcutter-is-empty/2203 "2019-12-03T18:20:08Z")

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Hi everyone, I’m using vtkCutter to compute the intersection of a plane and sphere. Is there a good way for me to determine if they don’t intersect at all? thank you in advance, -Merps

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## [Best VR headsets to use with VTK?](https://discourse.vtk.org/t/best-vr-headsets-to-use-with-vtk/2196)

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**Author:** [@msmerps](https://discourse.vtk.org/u/msmerps)\
**Replies:** 3\
**Last updated:** [December 3, 2019, 4:07pm UTC](https://discourse.vtk.org/t/best-vr-headsets-to-use-with-vtk/2196 "2019-12-03T16:07:02Z")

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Hi all, I’m interested in using VTK with a virtual reality headset but I don’t know which kind of headset I should buy. Based on this Kitware blog post from 2018 (https://blog.kitware.com/slicervirtualreality/), it seem…

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## [A question about exporting a large image(use vtkRenderLargeImage)](https://discourse.vtk.org/t/a-question-about-exporting-a-large-image-use-vtkrenderlargeimage/2199)

<div class="topic-metadata">

**Author:** [@sorlik](https://discourse.vtk.org/u/sorlik)\
**Replies:** 0\
**Last updated:** [December 3, 2019, 2:57am UTC](https://discourse.vtk.org/t/a-question-about-exporting-a-large-image-use-vtkrenderlargeimage/2199 "2019-12-03T02:57:38Z")

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I need to export the scene as a high-definition image, but the image is tiled through vtkRenderLargeImage(Use tiling to generate a large rendering). How can I export the high-definition image by filling ? Thanks.

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## [How to create a categorical legend?](https://discourse.vtk.org/t/how-to-create-a-categorical-legend/2195)

<div class="topic-metadata">

**Author:** [@michael23](https://discourse.vtk.org/u/michael23)\
**Replies:** 1\
**Last updated:** [December 2, 2019, 11:06pm UTC](https://discourse.vtk.org/t/how-to-create-a-categorical-legend/2195 "2019-12-02T23:06:38Z")

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Hi, I would like to use the class “vtkCategoryLegend” to add a legend in the lower right corner of my render window. Is there any example of how to use this class? Similar to the “gear type” example I found on the Para…

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## [Coverage is still messed up](https://discourse.vtk.org/t/coverage-is-still-messed-up/678)

<div class="topic-metadata">

**Author:** [@lorensen](https://discourse.vtk.org/u/lorensen)\
**Replies:** 9\
**Last updated:** [December 2, 2019, 3:47pm UTC](https://discourse.vtk.org/t/coverage-is-still-messed-up/678 "2019-12-02T15:47:40Z")

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Foks, Coverage is running but not reporting file coverage. Bill

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## [How to stop flickering issue during rotation](https://discourse.vtk.org/t/how-to-stop-flickering-issue-during-rotation/2192)

<div class="topic-metadata">

**Author:** [@Sathiya\_Moorthy](https://discourse.vtk.org/u/Sathiya_Moorthy)\
**Replies:** 0\
**Last updated:** [December 2, 2019, 12:03pm UTC](https://discourse.vtk.org/t/how-to-stop-flickering-issue-during-rotation/2192 "2019-12-02T12:03:46Z")

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I have the Vtk RendererWindow, It display a vtkOpenGLActor. It flickers whenever the actor is rotated by mouse movement. Is there any way to prevent this flickering?

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## [How to get the transform matrix from vtkProcrustesAlignmentFilter?](https://discourse.vtk.org/t/how-to-get-the-transform-matrix-from-vtkprocrustesalignmentfilter/2179)

<div class="topic-metadata">

**Author:** [@michaelhogg](https://discourse.vtk.org/u/michaelhogg)\
**Replies:** 2\
**Last updated:** [December 1, 2019, 10:41pm UTC](https://discourse.vtk.org/t/how-to-get-the-transform-matrix-from-vtkprocrustesalignmentfilter/2179 "2019-12-01T22:41:53Z")

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Hi all, I am using vtkProcrustesAlignmentFilter to align 2 polydata objects that have the same number of points. I wanted to get the transform matrix out from this filter. I can do this using the following code: procru…

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## [Timer and Mouse call back connection](https://discourse.vtk.org/t/timer-and-mouse-call-back-connection/2188)

<div class="topic-metadata">

**Author:** [@banikr](https://discourse.vtk.org/u/banikr)\
**Replies:** 0\
**Last updated:** [December 1, 2019, 5:16pm UTC](https://discourse.vtk.org/t/timer-and-mouse-call-back-connection/2188 "2019-12-01T17:16:59Z")

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What I am trying to do is very simple in concept, but I don’t know how to do it in VTK as a beginner. I have picked up a point in a 3D image using Mousecallback. The point I am calling seed point gives me world coordina…

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## [vtkStringArray is not properly added when vtkUnstructuredGrid is outputted as PVTU file](https://discourse.vtk.org/t/vtkstringarray-is-not-properly-added-when-vtkunstructuredgrid-is-outputted-as-pvtu-file/1684)

<div class="topic-metadata">

**Author:** [@vchan1186](https://discourse.vtk.org/u/vchan1186)\
**Replies:** 2\
**Last updated:** [December 1, 2019, 3:55am UTC](https://discourse.vtk.org/t/vtkstringarray-is-not-properly-added-when-vtkunstructuredgrid-is-outputted-as-pvtu-file/1684 "2019-12-01T03:55:02Z")

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I am trying to add a vtkStringArray to a vtkUnstructuredGrid using the AddArray method. The string array shows up in the spreadsheet view for serial vtu files, but does not appear when loading a pvtu file in ParaView. I…

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## [vtkSliderWidget doesn't display in my render window python](https://discourse.vtk.org/t/vtksliderwidget-doesnt-display-in-my-render-window-python/2186)

<div class="topic-metadata">

**Author:** [@kimia.af1998](https://discourse.vtk.org/u/kimia.af1998)\
**Replies:** 0\
**Last updated:** [November 30, 2019, 2:24pm UTC](https://discourse.vtk.org/t/vtksliderwidget-doesnt-display-in-my-render-window-python/2186 "2019-11-30T14:24:04Z")

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Hi I have four QVTKRenderWindowInteractor and wants to add a slider into 3 of them. These sliders help to slide through slices. I cannot insert the slider into my render windows. I get this Error : and Here is my…

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## [TimerCallBack and MouseCallBack](https://discourse.vtk.org/t/timercallback-and-mousecallback/2185)

<div class="topic-metadata">

**Author:** [@banikr](https://discourse.vtk.org/u/banikr)\
**Replies:** 3\
**Last updated:** [November 30, 2019, 3:50am UTC](https://discourse.vtk.org/t/timercallback-and-mousecallback/2185 "2019-11-30T03:50:09Z")

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Hello all, I am working on TImerCallback and MouseCallback. In my MouseCallback I choose a point(seedPoint) with mouse click in a glyph3D field. It creates a sphere in the seedPoint. Now the glyphfields has vectors an…

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## [Bounding box of vtkImageData](https://discourse.vtk.org/t/bounding-box-of-vtkimagedata/2178)

<div class="topic-metadata">

**Author:** [@lassoan](https://discourse.vtk.org/u/lassoan)\
**Replies:** 3\
**Last updated:** [November 29, 2019, 1:41pm UTC](https://discourse.vtk.org/t/bounding-box-of-vtkimagedata/2178 "2019-11-29T13:41:59Z")

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While trying to find out why vtkProbeFilter often fails when probing a single-slice 3D volume with a line, I’ve found that vtkProbeFilter returns early because it finds that the line’s bounding box does not intersect the…

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## [OpenGL2 / Glew error with vtk8.2 in PyCharm](https://discourse.vtk.org/t/opengl2-glew-error-with-vtk8-2-in-pycharm/2181)

<div class="topic-metadata">

**Author:** [@Voidling](https://discourse.vtk.org/u/Voidling)\
**Replies:** 0\
**Last updated:** [November 29, 2019, 1:01am UTC](https://discourse.vtk.org/t/opengl2-glew-error-with-vtk8-2-in-pycharm/2181 "2019-11-29T01:01:17Z")

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Hello, i am facing an issue where i find no adequate help in several online forums. What i did so far is pretty simpel: Using PyCharm IDE Created Conda Python3.7 venv installed vtk package (8.2.0) via conda, which w…

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## [How to convert from 2D polygons (vtkPolydata) to a 3D volumen](https://discourse.vtk.org/t/how-to-convert-from-2d-polygons-vtkpolydata-to-a-3d-volumen/2175)

<div class="topic-metadata">

**Author:** [@vacingforo](https://discourse.vtk.org/u/vacingforo)\
**Replies:** 1\
**Last updated:** [November 28, 2019, 8:47pm UTC](https://discourse.vtk.org/t/how-to-convert-from-2d-polygons-vtkpolydata-to-a-3d-volumen/2175 "2019-11-28T20:47:38Z")

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How to convert from 2D polygons (vtkPolydata) to a 3D volumen? Check the following image:

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## [VTK blend color in wierd way with vtkassembly](https://discourse.vtk.org/t/vtk-blend-color-in-wierd-way-with-vtkassembly/2149)

<div class="topic-metadata">

**Author:** [@lainegates](https://discourse.vtk.org/u/lainegates)\
**Replies:** 3\
**Last updated:** [November 27, 2019, 9:38am UTC](https://discourse.vtk.org/t/vtk-blend-color-in-wierd-way-with-vtkassembly/2149 "2019-11-27T09:38:49Z")

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When I update VTK to version 8.2.0, I encounter a specical bug that VTK will blend color with ‘vtkAssembly’ in wierd way comparing to behavior by vtkActor . While blend color with vtkAssembly, it seems that VTK just ad…

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## [Number of output ports](https://discourse.vtk.org/t/number-of-output-ports/2162)

<div class="topic-metadata">

**Author:** [@HugoC](https://discourse.vtk.org/u/HugoC)\
**Replies:** 13\
**Last updated:** [November 28, 2019, 8:52am UTC](https://discourse.vtk.org/t/number-of-output-ports/2162 "2019-11-28T08:52:48Z")

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Hello, I want to set a model in .obj on the web and i have a problem. I did my tests with a .obj found on the web and it’s working well, it’s a lego man with 6 outputPorts, corresponding to each part of his body. I tr…

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## [How to use vtk with a scenegraph](https://discourse.vtk.org/t/how-to-use-vtk-with-a-scenegraph/2160)

<div class="topic-metadata">

**Author:** [@scotsman60](https://discourse.vtk.org/u/scotsman60)\
**Replies:** 3\
**Last updated:** [November 27, 2019, 9:30pm UTC](https://discourse.vtk.org/t/how-to-use-vtk-with-a-scenegraph/2160 "2019-11-27T21:30:46Z")

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Hello!!! I have a need to integrate vtk with a scenegraph. My application is display of hierarchical (think CAD Assembly/Part) models where I have lots of ‘Parts’ that contain 1D, 2D and 3D meshes that I currently displ…

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## [point picking in .vtk file](https://discourse.vtk.org/t/point-picking-in-vtk-file/2171)

<div class="topic-metadata">

**Author:** [@banikr](https://discourse.vtk.org/u/banikr)\
**Replies:** 0\
**Last updated:** [November 27, 2019, 6:44pm UTC](https://discourse.vtk.org/t/point-picking-in-vtk-file/2171 "2019-11-27T18:44:18Z")

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Hello all, I am working with a .vtk file of the brain which consists of principal eigenvectors. Please see the thresholded brain image and zoomed up version(glyphs) in the images. Now I want to pick a seed point in…

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## [Errors on a very simple ITK+VTK+Qt program](https://discourse.vtk.org/t/errors-on-a-very-simple-itk-vtk-qt-program/2169)

<div class="topic-metadata">

**Author:** [@BorisM](https://discourse.vtk.org/u/BorisM)\
**Replies:** 0\
**Last updated:** [November 27, 2019, 4:53pm UTC](https://discourse.vtk.org/t/errors-on-a-very-simple-itk-vtk-qt-program/2169 "2019-11-27T16:53:37Z")

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I am new to ITK/VTK programming. I have written a very simple program using ITK,VTK and Qt, inspired from VTK examples (mainly Examples/GUI/Qt/FourPaneViewer). It simply allows to visualize a 3D image, loaded via ITK. I…

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## [Requesting Thoughts Concerning using VTK as Mesh Data Structure for FEA Software](https://discourse.vtk.org/t/requesting-thoughts-concerning-using-vtk-as-mesh-data-structure-for-fea-software/2153)

<div class="topic-metadata">

**Author:** [@Keith\_Ballard](https://discourse.vtk.org/u/Keith_Ballard)\
**Replies:** 5\
**Last updated:** [November 27, 2019, 4:20pm UTC](https://discourse.vtk.org/t/requesting-thoughts-concerning-using-vtk-as-mesh-data-structure-for-fea-software/2153 "2019-11-27T16:20:38Z")

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Hello All, I have been familiar with VTK for some time and use it extensively in ParaView plugins/VTK modules I write for post-processing of FEA data, but my use of VTK has been limited to post-processing. What I am no…

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