# Support

**URL:** https://discourse.vtk.org/c/support/6.md?page=10

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

**Page:** 11

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## [2D MPR](https://discourse.vtk.org/t/2d-mpr/15544)

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**Author:** [@gunavg](https://discourse.vtk.org/u/gunavg)\
**Replies:** 0\
**Last updated:** [April 26, 2025, 11:14am UTC](https://discourse.vtk.org/t/2d-mpr/15544 "2025-04-26T11:14:12Z")

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Hi I am using VTK 9.2.0 and QT 5.2.1. I am working in fourpaneviewer sample to display 2MPR with 3D cursor. I am able to get 2D MPR how can i develop or integrate 3D cursor with that? Any suggestion, reference or sam…

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## [Usage of QQuickVTKItem::dispatch\_async in QML](https://discourse.vtk.org/t/usage-of-qquickvtkitem-dispatch-async-in-qml/15536)

<div class="topic-metadata">

**Author:** [@excommunicado](https://discourse.vtk.org/u/excommunicado)\
**Replies:** 0\
**Last updated:** [April 22, 2025, 8:43pm UTC](https://discourse.vtk.org/t/usage-of-qquickvtkitem-dispatch-async-in-qml/15536 "2025-04-22T20:43:05Z")

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I’ve already posted my issue here. VTK developers asked me to move it here. Lets assume I’m developing a DICOM viewer using volume rendering in VTK. To integrate QML with VTK, we have QQuickVTKItem. Two main concepts…

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## [vtkCellGrid Examples?](https://discourse.vtk.org/t/vtkcellgrid-examples/15503)

<div class="topic-metadata">

**Author:** [@raungst](https://discourse.vtk.org/u/raungst)\
**Replies:** 3\
**Last updated:** [April 22, 2025, 7:45pm UTC](https://discourse.vtk.org/t/vtkcellgrid-examples/15503 "2025-04-22T19:45:44Z")

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Hello, I’m trying to look into the feasibility of replacing an unstructured grid in my program with a vtkCellGrid to be able to support discontinuous contours. Are there any simple examples on how to get the connectivit…

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## [vtk shows black window](https://discourse.vtk.org/t/vtk-shows-black-window/13437)

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**Author:** [@sstezura](https://discourse.vtk.org/u/sstezura)\
**Replies:** 9\
**Last updated:** [April 22, 2025, 7:40am UTC](https://discourse.vtk.org/t/vtk-shows-black-window/13437 "2025-04-22T07:40:18Z")

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Hi, I managed to upgrad from vtk 5.5 to vtk 9.3 with my 32bit application (now 64bit application). But there seems to be a problem, I am trying to push points into the cloud and want to show them, as they are shown in …

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## [VTK Poisson Reconstruction / Powercrust modules?](https://discourse.vtk.org/t/vtk-poisson-reconstruction-powercrust-modules/15530)

<div class="topic-metadata">

**Author:** [@jimiheinonen](https://discourse.vtk.org/u/jimiheinonen)\
**Replies:** 0\
**Last updated:** [April 22, 2025, 6:57am UTC](https://discourse.vtk.org/t/vtk-poisson-reconstruction-powercrust-modules/15530 "2025-04-22T06:57:17Z")

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Hello! I am trying to compile Poisson Reconstruction / Powercrust modules. Unfortunately it seems after generation the modules are not available in the build/Remote folder (and hence are not built at all). I have set VTK…

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## [vtkMarchingCubes & vtkImageThreshold generate noticeable staircase-like textures](https://discourse.vtk.org/t/vtkmarchingcubes-vtkimagethreshold-generate-noticeable-staircase-like-textures/15525)

<div class="topic-metadata">

**Author:** [@yangyang117](https://discourse.vtk.org/u/yangyang117)\
**Replies:** 0\
**Last updated:** [April 21, 2025, 8:30am UTC](https://discourse.vtk.org/t/vtkmarchingcubes-vtkimagethreshold-generate-noticeable-staircase-like-textures/15525 "2025-04-21T08:30:28Z")

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After reading the CT data, if I use vtkImageThreshold for threshold segmentation and then use vtkMarchingCubes to generate the polydata, the resulting polydata has very noticeable staircase-like textures. However, when I…

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## [Threading WASM. Setting the backend.](https://discourse.vtk.org/t/threading-wasm-setting-the-backend/14975)

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**Author:** [@Jens\_Munk\_Hansen](https://discourse.vtk.org/u/Jens_Munk_Hansen)\
**Replies:** 3\
**Last updated:** [April 19, 2025, 7:49pm UTC](https://discourse.vtk.org/t/threading-wasm-setting-the-backend/14975 "2025-04-19T19:49:37Z")

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After getting everything to compile, I tried setting the backend to STDThread (WASM). I got a callstack like this $std::\_\_2::\_\_throw\_system\_error(int, char const\*) @ system\_error.cpp:218 $std::\_\_2::thread::thread\<vtk::d…

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## [Base64 woes & associated questions regarding how vtk reads data in the xml form](https://discourse.vtk.org/t/base64-woes-associated-questions-regarding-how-vtk-reads-data-in-the-xml-form/15517)

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**Author:** [@Subject303](https://discourse.vtk.org/u/Subject303)\
**Replies:** 1\
**Last updated:** [April 19, 2025, 6:51pm UTC](https://discourse.vtk.org/t/base64-woes-associated-questions-regarding-how-vtk-reads-data-in-the-xml-form/15517 "2025-04-19T18:51:19Z")

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I’m suffering at the behest of the vtk xml format and would appreciate some advice regarding what format the data should be in. So as an exercise I’m creating a vtp file that stores the coordinates of a 27 point, cube, …

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## [Error glBlitFramebuffer1 OpenGL errors when setting Interactor in Qt](https://discourse.vtk.org/t/error-glblitframebuffer1-opengl-errors-when-setting-interactor-in-qt/14522)

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**Author:** [@sss](https://discourse.vtk.org/u/sss)\
**Replies:** 2\
**Last updated:** [April 18, 2025, 11:39am UTC](https://discourse.vtk.org/t/error-glblitframebuffer1-opengl-errors-when-setting-interactor-in-qt/14522 "2025-04-18T11:39:28Z")

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Hi, I am using Qt6.5.3 with VTK 9.3.1 in Visual Studio. I have 2 QVTKOpenGLNativeWidget both work fine and able to display 3D and 2D, but whenever I change the interactor of the render window, there will be error every …

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## [How to Ensure One Actor Always Renders on Top of Another Actor in VTK Without Z-Fighting?](https://discourse.vtk.org/t/how-to-ensure-one-actor-always-renders-on-top-of-another-actor-in-vtk-without-z-fighting/15485)

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**Author:** [@yarenakin](https://discourse.vtk.org/u/yarenakin)\
**Replies:** 6\
**Last updated:** [April 18, 2025, 11:36am UTC](https://discourse.vtk.org/t/how-to-ensure-one-actor-always-renders-on-top-of-another-actor-in-vtk-without-z-fighting/15485 "2025-04-18T11:36:07Z")

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I am working with two actors in a 3D scene, where I need one actor (highlightActor) to always appear on top of another actor (currentActor), even when they are in close proximity or overlapping. Currently, I’m facing Z-f…

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## [cmake not using VTK\_MODULE\_ENABLE\_VTK\_GuiSupportQt or VTK\_MODULE\_ENABLE\_VTK\_GuiSupportQtQuick?](https://discourse.vtk.org/t/cmake-not-using-vtk-module-enable-vtk-guisupportqt-or-vtk-module-enable-vtk-guisupportqtquick/15510)

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**Author:** [@Tomasso](https://discourse.vtk.org/u/Tomasso)\
**Replies:** 3\
**Last updated:** [April 18, 2025, 11:31am UTC](https://discourse.vtk.org/t/cmake-not-using-vtk-module-enable-vtk-guisupportqt-or-vtk-module-enable-vtk-guisupportqtquick/15510 "2025-04-18T11:31:45Z")

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I’m building VTK-9.4.2, on MacOS Sequoia. After downloading the source I issue: cmake -DVTK\_MODULE\_ENABLE\_VTK\_GuiSupportQt=YES -DVTK\_MODULE\_ENABLE\_VTK\_GuiSupportQtQuick=YES -DVTK\_MODULE\_ENABLE\_VTK\_ViewsQt=YES .. When …

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## [slow read file](https://discourse.vtk.org/t/slow-read-file/15484)

<div class="topic-metadata">

**Author:** [@damien-mattei](https://discourse.vtk.org/u/damien-mattei)\
**Replies:** 3\
**Last updated:** [April 17, 2025, 2:40pm UTC](https://discourse.vtk.org/t/slow-read-file/15484 "2025-04-17T14:40:44Z")

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Hi, when reading a 6Gb binary file (only header is text) it takes approx 98 seconds which seems slow withis code: if data\_structure == 'STRUCTURED\_POINTS': reader = vtk.vtkStructuredPointsReader() # here you can add ot…

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## [Draw Curve on Mesh with vtkContourWidget](https://discourse.vtk.org/t/draw-curve-on-mesh-with-vtkcontourwidget/15504)

<div class="topic-metadata">

**Author:** [@Suleyman\_Turkoglu](https://discourse.vtk.org/u/Suleyman_Turkoglu)\
**Replies:** 3\
**Last updated:** [April 17, 2025, 11:30am UTC](https://discourse.vtk.org/t/draw-curve-on-mesh-with-vtkcontourwidget/15504 "2025-04-17T11:30:05Z")

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I can draw a curve using vtkContourWidget. The control points can be on the polydata, but I want the curve itself to be above the polydata. Is it possible to achieve that using vtkContourWidget?

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## [vtkPolyDataConnectivityFilter bug?](https://discourse.vtk.org/t/vtkpolydataconnectivityfilter-bug/15501)

<div class="topic-metadata">

**Author:** [@mau\_igna\_06](https://discourse.vtk.org/u/mau_igna_06)\
**Replies:** 1\
**Last updated:** [April 15, 2025, 11:44pm UTC](https://discourse.vtk.org/t/vtkpolydataconnectivityfilter-bug/15501 "2025-04-15T23:44:33Z")

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Hi, Why Case 2a, Case 2b and Case 2c do not have the same number of points? Is this a bug? Example below: # points points = vtk.vtkPoints() points.InsertNextPoint(0, 0, 10) points.InsertNextPoint(2, 0, 5) points.Inser…

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## [VTKHDF size is way bigger than VTM files. Is this expected?](https://discourse.vtk.org/t/vtkhdf-size-is-way-bigger-than-vtm-files-is-this-expected/15499)

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**Author:** [@lorenzovecchietti](https://discourse.vtk.org/u/lorenzovecchietti)\
**Replies:** 3\
**Last updated:** [April 15, 2025, 1:12pm UTC](https://discourse.vtk.org/t/vtkhdf-size-is-way-bigger-than-vtm-files-is-this-expected/15499 "2025-04-15T13:12:16Z")

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I have two scripts that operate on the same set of files, which consists of 160,000 PolyData objects created using pyVista. Initially, I used pv.multiblock and its .save() method, which employs vtkXMLMultiBlockDataWriter.…

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## [Image synthesis for parallel volume rendering](https://discourse.vtk.org/t/image-synthesis-for-parallel-volume-rendering/15497)

<div class="topic-metadata">

**Author:** [@luhailin](https://discourse.vtk.org/u/luhailin)\
**Replies:** 0\
**Last updated:** [April 15, 2025, 2:48am UTC](https://discourse.vtk.org/t/image-synthesis-for-parallel-volume-rendering/15497 "2025-04-15T02:48:31Z")

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When I use VTK’s parallel rendering related classes, I find that volume rendering can’t correctly synthesize images, and surface rendering and volume rendering cover problems. Surface rendering is always displayed in fro…

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## [Groups of vertices or cells](https://discourse.vtk.org/t/groups-of-vertices-or-cells/15488)

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**Author:** [@Borek\_Patzak](https://discourse.vtk.org/u/Borek_Patzak)\
**Replies:** 5\
**Last updated:** [April 14, 2025, 10:37am UTC](https://discourse.vtk.org/t/groups-of-vertices-or-cells/15488 "2025-04-14T10:37:37Z")

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Hello everyone, I am an FE guy working with large, unstructured datasets, and I am looking for advice on how to efficiently represent groups of vertices or cells in VTK. One typical scenario in my work involves selecti…

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## [Survey about updating minimum OpenGL version to 4.1](https://discourse.vtk.org/t/survey-about-updating-minimum-opengl-version-to-4-1/13631)

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**Author:** [@jaswantp](https://discourse.vtk.org/u/jaswantp)\
**Replies:** 4\
**Last updated:** [April 13, 2025, 9:25pm UTC](https://discourse.vtk.org/t/survey-about-updating-minimum-opengl-version-to-4-1/13631 "2025-04-13T21:25:24Z")

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We’re proposing to bump the minimum OpenGL version from 3.2 to 4.1. As VTK uses a core profile context and asks for the highest available version from the OS, chances are you’re already using 4.6. Please let us know if y…

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## [High fidelity ray traced volume rendering in VTK](https://discourse.vtk.org/t/high-fidelity-ray-traced-volume-rendering-in-vtk/15487)

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**Author:** [@Devadathan\_A](https://discourse.vtk.org/u/Devadathan_A)\
**Replies:** 0\
**Last updated:** [April 10, 2025, 7:07pm UTC](https://discourse.vtk.org/t/high-fidelity-ray-traced-volume-rendering-in-vtk/15487 "2025-04-10T19:07:31Z")

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I was trying to create a simple tool for volume rendering of medical images using VTK for Python, but currently the issue I am facing is that the volume render does not look visually appealing (when compared to similar t…

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## [Struggling to use vtkExtractUnstructuredGrid](https://discourse.vtk.org/t/struggling-to-use-vtkextractunstructuredgrid/15471)

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**Author:** [@Subject303](https://discourse.vtk.org/u/Subject303)\
**Replies:** 2\
**Last updated:** [April 8, 2025, 3:24pm UTC](https://discourse.vtk.org/t/struggling-to-use-vtkextractunstructuredgrid/15471 "2025-04-08T15:24:54Z")

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Hi I’m trying to convert a vtkUnstructuredGrid object read from a .case file into paraview and use the vtkExtractUnstructuredGrid filter to convert it to a vtkPolyData so that I can then use various polydata filters to g…

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## [vtkContourTriangulator fails for closed, 2d rectangle.](https://discourse.vtk.org/t/vtkcontourtriangulator-fails-for-closed-2d-rectangle/15474)

<div class="topic-metadata">

**Author:** [@rdbrn](https://discourse.vtk.org/u/rdbrn)\
**Replies:** 1\
**Last updated:** [April 7, 2025, 2:15pm UTC](https://discourse.vtk.org/t/vtkcontourtriangulator-fails-for-closed-2d-rectangle/15474 "2025-04-07T14:15:46Z")

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I am using vtkContourTriangulator to triangulate 2d shapes. But it fails for a simple rectangular shape: In related post: vtkContourTriangulator (Triangulation failed) - Development - VTK it is mentioned that triangu…

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## [How to color each cell under vtkunstructueredgrid](https://discourse.vtk.org/t/how-to-color-each-cell-under-vtkunstructueredgrid/15477)

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**Author:** [@mskmsk](https://discourse.vtk.org/u/mskmsk)\
**Replies:** 1\
**Last updated:** [April 7, 2025, 7:03am UTC](https://discourse.vtk.org/t/how-to-color-each-cell-under-vtkunstructueredgrid/15477 "2025-04-07T07:03:50Z")

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How to color cells of an unstructuredgrid. I could color by point data. I could color by actor. But I could not apply color for each cell. I used GetCellData of vtkUnstructuredGrid… and its showing as white.

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## [In Activiz No SetValue and GetValue in vtkCharArray and other Array](https://discourse.vtk.org/t/in-activiz-no-setvalue-and-getvalue-in-vtkchararray-and-other-array/15447)

<div class="topic-metadata">

**Author:** [@INCREADIBLE](https://discourse.vtk.org/u/INCREADIBLE)\
**Replies:** 3\
**Last updated:** [April 5, 2025, 10:56am UTC](https://discourse.vtk.org/t/in-activiz-no-setvalue-and-getvalue-in-vtkchararray-and-other-array/15447 "2025-04-05T10:56:59Z")

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Hi I am tring to move C++ VTK code to activiz 9.4 ,but meet some problem in vtkIntArray, vtkCharArray, etc. These array seems do not have SetValue and GetValue any more ,and they only have SetTuple and GetTuple to set/g…

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## [VTK.js ImageData Rendering width react](https://discourse.vtk.org/t/vtk-js-imagedata-rendering-width-react/15464)

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**Author:** [@psb01126](https://discourse.vtk.org/u/psb01126)\
**Replies:** 1\
**Last updated:** [April 3, 2025, 1:42pm UTC](https://discourse.vtk.org/t/vtk-js-imagedata-rendering-width-react/15464 "2025-04-03T13:42:15Z")

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Hello, I’m trying to develop a website using Python and react. However, there is a problem that image data is generated normally, but rendering is not possible. When I tested it with the conesource on the vtk homepage,…

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## [Question on vtkRenderWindowInteractor](https://discourse.vtk.org/t/question-on-vtkrenderwindowinteractor/15469)

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**Author:** [@Bipey](https://discourse.vtk.org/u/Bipey)\
**Replies:** 1\
**Last updated:** [April 2, 2025, 10:02pm UTC](https://discourse.vtk.org/t/question-on-vtkrenderwindowinteractor/15469 "2025-04-02T22:02:02Z")

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Hello, I was exploring examples of vtkRenderWindowInteractor when I noticed a strange behavior. When I press the key 3 in the render window, the entire window turns pink. I am not sure whether this is intentional or a b…

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## [Color does not match with values on look up table](https://discourse.vtk.org/t/color-does-not-match-with-values-on-look-up-table/15459)

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**Author:** [@vryy](https://discourse.vtk.org/u/vryy)\
**Replies:** 4\
**Last updated:** [April 1, 2025, 11:20pm UTC](https://discourse.vtk.org/t/color-does-not-match-with-values-on-look-up-table/15459 "2025-04-01T23:20:11Z")

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Hello I try to make a simple example to visualize scalar data on vtkUnstructuredGrid. The code is below import vtk # Create the 8-node cube (hexahedron) points = vtk.vtkPoints() points.InsertNextPoint(0, 0, 0) # Node…

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## [integrating VTK with QT](https://discourse.vtk.org/t/integrating-vtk-with-qt/15432)

<div class="topic-metadata">

**Author:** [@Emmynabs](https://discourse.vtk.org/u/Emmynabs)\
**Replies:** 9\
**Last updated:** [April 1, 2025, 8:07am UTC](https://discourse.vtk.org/t/integrating-vtk-with-qt/15432 "2025-04-01T08:07:50Z")

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I need assistance integrating VTK with QT, i have tried integrating them but my QT buttons do not work when i run the application. images do not render when i click the buttons to render them.

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## [Copying geometry from poly data clipper to another polydata using original IDs from ID filter](https://discourse.vtk.org/t/copying-geometry-from-poly-data-clipper-to-another-polydata-using-original-ids-from-id-filter/15451)

<div class="topic-metadata">

**Author:** [@jimiheinonen](https://discourse.vtk.org/u/jimiheinonen)\
**Replies:** 1\
**Last updated:** [April 1, 2025, 6:39am UTC](https://discourse.vtk.org/t/copying-geometry-from-poly-data-clipper-to-another-polydata-using-original-ids-from-id-filter/15451 "2025-04-01T06:39:24Z")

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Hey! I am looking to copy existing geometry inside a clipper from one polydata to another polydata, using original IDs from vtkIdFilter. I can get the original Ids from the filter, but how would I get around to copying t…

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## [python custom render pass](https://discourse.vtk.org/t/python-custom-render-pass/5743)

<div class="topic-metadata">

**Author:** [@devmessias](https://discourse.vtk.org/u/devmessias)\
**Replies:** 2\
**Last updated:** [April 1, 2025, 3:04am UTC](https://discourse.vtk.org/t/python-custom-render-pass/5743 "2025-04-01T03:04:58Z")

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Hi, I’m trying to create a custom render pass using just python. It seems that it’s impossible create a subclass in python using vtkRenderDelegate class myPass(vtk.vtkRendererDelegate): # def \_\_init\_\_(self, \*args, …

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## [Creating a subclass for vtkActor](https://discourse.vtk.org/t/creating-a-subclass-for-vtkactor/15449)

<div class="topic-metadata">

**Author:** [@jimiheinonen](https://discourse.vtk.org/u/jimiheinonen)\
**Replies:** 0\
**Last updated:** [March 31, 2025, 8:40am UTC](https://discourse.vtk.org/t/creating-a-subclass-for-vtkactor/15449 "2025-03-31T08:40:23Z")

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Hey, I am looking to override vtkActor and simply adding a name property (subclass name is namedActor). Now I’ve got the code compiling, but when rendering the window, the geometry of the actor is invisible. Am I missing…

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