# Support

**URL:** https://discourse.vtk.org/c/support/6.md?page=7

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

**Page:** 8

---

## [Texture mapping on a polygon](https://discourse.vtk.org/t/texture-mapping-on-a-polygon/15558)

<div class="topic-metadata">

**Author:** [@Balaji\_Ram](https://discourse.vtk.org/u/Balaji_Ram)\
**Replies:** 5\
**Last updated:** [July 25, 2025, 7:15pm UTC](https://discourse.vtk.org/t/texture-mapping-on-a-polygon/15558 "2025-07-25T19:15:08Z")

</div>

Hello, I am working on replacing the Visualization in our legacy application that earlier used OpenGL and trying to use VTK as a replacement. When applying a texture to a polygon as shown below, the texture image does …

---

## [How to programmatically determine if mesa dlls are needed to display a scene?](https://discourse.vtk.org/t/how-to-programmatically-determine-if-mesa-dlls-are-needed-to-display-a-scene/15864)

<div class="topic-metadata">

**Author:** [@toro](https://discourse.vtk.org/u/toro)\
**Replies:** 4\
**Last updated:** [July 25, 2025, 3:17pm UTC](https://discourse.vtk.org/t/how-to-programmatically-determine-if-mesa-dlls-are-needed-to-display-a-scene/15864 "2025-07-25T15:17:44Z")

</div>

Hi, I can display a VTK scene both on a Windows Remote machine through RDP (with no GPU), and on a local Windows machine. Through RDP, I managed to do this by loading GitHub - pal1000/mesa-dist-win: Pre-built Mesa3D dri…

---

## [QVTKOpenGLNativeWidget vkt9+qt5 framebuffer errors when using setParent](https://discourse.vtk.org/t/qvtkopenglnativewidget-vkt9-qt5-framebuffer-errors-when-using-setparent/8645)

<div class="topic-metadata">

**Author:** [@Michal\_Chlebiej](https://discourse.vtk.org/u/Michal_Chlebiej)\
**Replies:** 4\
**Last updated:** [July 25, 2025, 7:51am UTC](https://discourse.vtk.org/t/qvtkopenglnativewidget-vkt9-qt5-framebuffer-errors-when-using-setparent/8645 "2025-07-25T07:51:02Z")

</div>

Hi, I’m trying to migrate my code from Vtk 8.2 to 9.1 using QT 5.15. My main problem is VTK+QT widget. I’ve been using my own VTKQT widget implementation for some years based on QVTKOpenGLNativeWidget. After updating t…

---

## [Creating custom filter in Python](https://discourse.vtk.org/t/creating-custom-filter-in-python/15854)

<div class="topic-metadata">

**Author:** [@citronella3alain](https://discourse.vtk.org/u/citronella3alain)\
**Replies:** 2\
**Last updated:** [July 24, 2025, 1:00pm UTC](https://discourse.vtk.org/t/creating-custom-filter-in-python/15854 "2025-07-24T13:00:22Z")

</div>

I’ve not found many examples of creating custom vtk filters in python so I followed this one: Developing Custom Filters and Algorithms in VTK However, it doesn’t seem to work: custom\_filter.ipynb (7.8 KB) It doesn’t s…

---

## [qt+vtk9.4.2 mousemoveevent trigger twice](https://discourse.vtk.org/t/qt-vtk9-4-2-mousemoveevent-trigger-twice/15855)

<div class="topic-metadata">

**Author:** [@LostRaccoon](https://discourse.vtk.org/u/LostRaccoon)\
**Replies:** 0\
**Last updated:** [July 24, 2025, 1:42am UTC](https://discourse.vtk.org/t/qt-vtk9-4-2-mousemoveevent-trigger-twice/15855 "2025-07-24T01:42:36Z")

</div>

Compared to VTK 9.3, VTK 9.4.2 added the following code in QVTKInteractorAdapter if (t == QEvent::MouseMove || t == QEvent::HoverMove) { iren-\>InvokeEvent(vtkCommand::MouseMoveEvent, e2); } but in “QVTKOpenGLNativeW…

---

## [VTK with Xvfb](https://discourse.vtk.org/t/vtk-with-xvfb/15843)

<div class="topic-metadata">

**Author:** [@bfosso](https://discourse.vtk.org/u/bfosso)\
**Replies:** 4\
**Last updated:** [July 23, 2025, 4:56pm UTC](https://discourse.vtk.org/t/vtk-with-xvfb/15843 "2025-07-23T16:56:49Z")

</div>

Hi All, I have been making figures with VTK in a Docker container via Xvfb for a while now with no complaints. However, I recently updated the container dependencies and found that things no longer work with vtk==9.5.0. …

---

## [Keep only edges that create a closed loop](https://discourse.vtk.org/t/keep-only-edges-that-create-a-closed-loop/15847)

<div class="topic-metadata">

**Author:** [@mau\_igna\_06](https://discourse.vtk.org/u/mau_igna_06)\
**Replies:** 6\
**Last updated:** [July 22, 2025, 8:18pm UTC](https://discourse.vtk.org/t/keep-only-edges-that-create-a-closed-loop/15847 "2025-07-22T20:18:25Z")

</div>

Hi, I have an output from vtkFeatureEdges, only keeping the boundary edges. See picture below: I’d like to able to create a planar face for the closed yellow loop inside the to keep red marker. I’ve tried vtkStripp…

---

## [How to cast shadows from environmental lighting onto transparent shadow receiver?](https://discourse.vtk.org/t/how-to-cast-shadows-from-environmental-lighting-onto-transparent-shadow-receiver/15844)

<div class="topic-metadata">

**Author:** [@scotsman60](https://discourse.vtk.org/u/scotsman60)\
**Replies:** 3\
**Last updated:** [July 22, 2025, 7:42am UTC](https://discourse.vtk.org/t/how-to-cast-shadows-from-environmental-lighting-onto-transparent-shadow-receiver/15844 "2025-07-22T07:42:40Z")

</div>

Hello!!! I’m trying to render a scene that includes my model, a “ground plane” (planar mesh) and a Skybox. I want the lighting from the Skybox to cast shadows of the model onto the ground plane and I want the ground pla…

---

## [Can I assign different Camera passes to different renderers/render windows?](https://discourse.vtk.org/t/can-i-assign-different-camera-passes-to-different-renderers-render-windows/15848)

<div class="topic-metadata">

**Author:** [@scotsman60](https://discourse.vtk.org/u/scotsman60)\
**Replies:** 0\
**Last updated:** [July 22, 2025, 2:20am UTC](https://discourse.vtk.org/t/can-i-assign-different-camera-passes-to-different-renderers-render-windows/15848 "2025-07-22T02:20:52Z")

</div>

Hello!!!, I’m starting to use vtkCameraPass/SequencePass/RenderPassCollection primarily for the purpose of display outline highlights and using environmental lighting. I’m not saying I fully understand how it works, but…

---

## [Set vtkCubeAxesActor scale labels after vtkTransform](https://discourse.vtk.org/t/set-vtkcubeaxesactor-scale-labels-after-vtktransform/15825)

<div class="topic-metadata">

**Author:** [@Julien\_Champagnol](https://discourse.vtk.org/u/Julien_Champagnol)\
**Replies:** 2\
**Last updated:** [July 21, 2025, 3:44pm UTC](https://discourse.vtk.org/t/set-vtkcubeaxesactor-scale-labels-after-vtktransform/15825 "2025-07-21T15:44:52Z")

</div>

Hi, I am applying a vtkTransform to different actors and a vtkCubeAxesActor but this is changing the scale of the dimension. I would like the scale to stay the same (from 0 to 1 in this example). A workaround would…

---

## [Using AdaptiveSubdivisionFilter to triangulate polygon](https://discourse.vtk.org/t/using-adaptivesubdivisionfilter-to-triangulate-polygon/15820)

<div class="topic-metadata">

**Author:** [@ScottUFR](https://discourse.vtk.org/u/ScottUFR)\
**Replies:** 1\
**Last updated:** [July 21, 2025, 1:35pm UTC](https://discourse.vtk.org/t/using-adaptivesubdivisionfilter-to-triangulate-polygon/15820 "2025-07-21T13:35:20Z")

</div>

I’m new to VTK and trying to triangulate a polygon using vtkAdaptiveSubdivisionFilter having failed using vtkPolygon-\>Triangulate and BoundedTriangulate. There doesn’t seem to be anything produced. Any idea what I’m mi…

---

## [VTK 9.5.0 WebAssembly 64-bit build fails with BigInt conversion error](https://discourse.vtk.org/t/vtk-9-5-0-webassembly-64-bit-build-fails-with-bigint-conversion-error/15794)

<div class="topic-metadata">

**Author:** [@leehyeonseop](https://discourse.vtk.org/u/leehyeonseop)\
**Replies:** 6\
**Last updated:** [July 21, 2025, 1:13pm UTC](https://discourse.vtk.org/t/vtk-9-5-0-webassembly-64-bit-build-fails-with-bigint-conversion-error/15794 "2025-07-21T13:13:22Z")

</div>

Hello, I’m trying to build VTK 9.5.0 with WebAssembly 64-bit support following the official documentation, but I’m encountering a BigInt conversion error during the build process. Special Note: Initially, the build was …

---

## [Could NOT find LibPROJ](https://discourse.vtk.org/t/could-not-find-libproj/15779)

<div class="topic-metadata">

**Author:** [@Dave-Allured](https://discourse.vtk.org/u/Dave-Allured)\
**Replies:** 6\
**Last updated:** [July 21, 2025, 12:17pm UTC](https://discourse.vtk.org/t/could-not-find-libproj/15779 "2025-07-21T12:17:07Z")

</div>

I am working with a new install of VTK 9.5.0 from MacPorts. Then I try to build GDCM, an application that uses VTK. I get this error at the CMake configuration stage: CMake Error at /opt/local/share/cmake-3.31/Modules…

---

## [vtkhdf simple HTG example](https://discourse.vtk.org/t/vtkhdf-simple-htg-example/15827)

<div class="topic-metadata">

**Author:** [@omdaniel](https://discourse.vtk.org/u/omdaniel)\
**Replies:** 1\
**Last updated:** [July 18, 2025, 3:20pm UTC](https://discourse.vtk.org/t/vtkhdf-simple-htg-example/15827 "2025-07-18T15:20:09Z")

</div>

I am following the example here to write a vtkhdf file for a HyperTreeGrid generate\_simple\_htg and was wondering if # Tree descriptions descriptors = ( # Tree 0 1, # Depth 1 0, 0…

---

## [Is there any difference between Gouraud and Phong?](https://discourse.vtk.org/t/is-there-any-difference-between-gouraud-and-phong/801)

<div class="topic-metadata">

**Author:** [@Jellby](https://discourse.vtk.org/u/Jellby)\
**Replies:** 6\
**Last updated:** [July 18, 2025, 1:44pm UTC](https://discourse.vtk.org/t/is-there-any-difference-between-gouraud-and-phong/801 "2025-07-18T13:44:46Z")

</div>

I see a clear difference between flat interpolation and Gouraud/Phong, but the two latter look pixel-identical to me. I’ve tried with specular=1, high and low specular powers, and still can’t spot any difference, except …

---

## [Using VTK LinePlot3D in an MFC child window](https://discourse.vtk.org/t/using-vtk-lineplot3d-in-an-mfc-child-window/15804)

<div class="topic-metadata">

**Author:** [@efrederick](https://discourse.vtk.org/u/efrederick)\
**Replies:** 10\
**Last updated:** [July 17, 2025, 4:46pm UTC](https://discourse.vtk.org/t/using-vtk-lineplot3d-in-an-mfc-child-window/15804 "2025-07-17T16:46:09Z")

</div>

Hello, I have an extensive MFC (commercial) application and we need to replace the 3D graph. We were hoping to incorporate the LinePlot3D application, but, after many hours of trying to get a mini-application to work, I…

---

## [Building libVTK with MinGW64 or bcc64](https://discourse.vtk.org/t/building-libvtk-with-mingw64-or-bcc64/7744)

<div class="topic-metadata">

**Author:** [@MVoloshin](https://discourse.vtk.org/u/MVoloshin)\
**Replies:** 13\
**Last updated:** [July 16, 2025, 11:10am UTC](https://discourse.vtk.org/t/building-libvtk-with-mingw64-or-bcc64/7744 "2025-07-16T11:10:23Z")

</div>

Hello! I’m trying to compile vtk-8.2 (I need exactly 8.x) library with MinGW64 (x86\_64-w64-mingw32-gcc toolchain). But I’m getting linker errors while building libvtksys (bunch of unresolved external errors). My target …

---

## [Can different scalar fields be displayed on different blocks of a vtkPartitioned DataSetCollection?](https://discourse.vtk.org/t/can-different-scalar-fields-be-displayed-on-different-blocks-of-a-vtkpartitioned-datasetcollection/15801)

<div class="topic-metadata">

**Author:** [@scotsman60](https://discourse.vtk.org/u/scotsman60)\
**Replies:** 2\
**Last updated:** [July 11, 2025, 4:43am UTC](https://discourse.vtk.org/t/can-different-scalar-fields-be-displayed-on-different-blocks-of-a-vtkpartitioned-datasetcollection/15801 "2025-07-11T04:43:56Z")

</div>

Hello!!!, I’m using VTK9.4 and Python 3.12. I have a vtkPartitionedDataSetCollection and I’m trying to display some of the blocks in constant colors and others using scalar point field data. I was hoping to achieve th…

---

## [vtkCubeSource / vtkBoxWidget coupling issue](https://discourse.vtk.org/t/vtkcubesource-vtkboxwidget-coupling-issue/15797)

<div class="topic-metadata">

**Author:** [@madmoonman](https://discourse.vtk.org/u/madmoonman)\
**Replies:** 3\
**Last updated:** [July 9, 2025, 9:53am UTC](https://discourse.vtk.org/t/vtkcubesource-vtkboxwidget-coupling-issue/15797 "2025-07-09T09:53:25Z")

</div>

Hello vtk-Experts, I’ve encountered yet another interesting problem. For a few years I have been developing an in-house tool using vtk and PyQt5. Currently I do not have a working minimal example, but I will build one i…

---

## [How to know which label is selected with mouse clicking when using vtkLabelPlacementMapper?](https://discourse.vtk.org/t/how-to-know-which-label-is-selected-with-mouse-clicking-when-using-vtklabelplacementmapper/15729)

<div class="topic-metadata">

**Author:** [@Guo8](https://discourse.vtk.org/u/Guo8)\
**Replies:** 1\
**Last updated:** [July 9, 2025, 7:43am UTC](https://discourse.vtk.org/t/how-to-know-which-label-is-selected-with-mouse-clicking-when-using-vtklabelplacementmapper/15729 "2025-07-09T07:43:16Z")

</div>

Dear users, I tried to use vtkLabelPlacementMapper to manage many labels, but failed to get the info about which label was selected by mouse clicking. I used HardwareSelector，it could give which actor was selected (the …

---

## [vtkGDALRasterReader for C++](https://discourse.vtk.org/t/vtkgdalrasterreader-for-c/15792)

<div class="topic-metadata">

**Author:** [@tholland](https://discourse.vtk.org/u/tholland)\
**Replies:** 1\
**Last updated:** [July 8, 2025, 4:15pm UTC](https://discourse.vtk.org/t/vtkgdalrasterreader-for-c/15792 "2025-07-08T16:15:53Z")

</div>

I’m trying to get data loaded in using the vtkGDALRasterReader class. My assumption is that it holds the elevation data in the scalars, similar to the vtkDEMReader. However, that doesn’t seem to be the case (or I’ve comp…

---

## [Excessive RAM Usage and System Crash When Opening Large \`.vtkhdf\` AMR Dataset in ParaView](https://discourse.vtk.org/t/excessive-ram-usage-and-system-crash-when-opening-large-vtkhdf-amr-dataset-in-paraview/15787)

<div class="topic-metadata">

**Author:** [@Hemangi\_Varkal](https://discourse.vtk.org/u/Hemangi_Varkal)\
**Replies:** 2\
**Last updated:** [July 8, 2025, 1:54pm UTC](https://discourse.vtk.org/t/excessive-ram-usage-and-system-crash-when-opening-large-vtkhdf-amr-dataset-in-paraview/15787 "2025-07-08T13:54:24Z")

</div>

Hello, I’m working with astrophysical simulation data and using Python to generate .vtkhdf files based on vtkOverlappingAMR. The code I’m using was created by adapting a sample provided for converting Overlapping AMR da…

---

## [Optimizing vtkOverlappingAMR: Reducing .vti File Count](https://discourse.vtk.org/t/optimizing-vtkoverlappingamr-reducing-vti-file-count/15623)

<div class="topic-metadata">

**Author:** [@Hemangi\_Varkal](https://discourse.vtk.org/u/Hemangi_Varkal)\
**Replies:** 7\
**Last updated:** [July 5, 2025, 2:18pm UTC](https://discourse.vtk.org/t/optimizing-vtkoverlappingamr-reducing-vti-file-count/15623 "2025-07-05T14:18:50Z")

</div>

Hi VTK community, I’m working with AMR data output from the RAMSES astrophysical simulation code. I’m using Python with VTK to convert this data into the vtkOverlappingAMR format for visualization. Currently, each AMR …

---

## [How to access original point IDs after subset extraction with vtkExtractPolyDataGeometry?](https://discourse.vtk.org/t/how-to-access-original-point-ids-after-subset-extraction-with-vtkextractpolydatageometry/15783)

<div class="topic-metadata">

**Author:** [@Tomasso](https://discourse.vtk.org/u/Tomasso)\
**Replies:** 2\
**Last updated:** [July 4, 2025, 6:27pm UTC](https://discourse.vtk.org/t/how-to-access-original-point-ids-after-subset-extraction-with-vtkextractpolydatageometry/15783 "2025-07-04T18:27:24Z")

</div>

I’m using VTK 9.3 for my C++ application. I use vtkInteractorStyleRubberBandPick and vtkExtractPolyDataGeometry to select a vtkPolyData subset of a full vtkPolyData object. How can I find each selected subset point in …

---

## [Where can I find a list of breaking API changes for each release.](https://discourse.vtk.org/t/where-can-i-find-a-list-of-breaking-api-changes-for-each-release/15780)

<div class="topic-metadata">

**Author:** [@vtbose](https://discourse.vtk.org/u/vtbose)\
**Replies:** 2\
**Last updated:** [July 3, 2025, 2:48pm UTC](https://discourse.vtk.org/t/where-can-i-find-a-list-of-breaking-api-changes-for-each-release/15780 "2025-07-03T14:48:38Z")

</div>

…The release notes does not seem to include these details. For example vtkGenericOpenGLRenderWindow::SetBackBuffer (VTK: vtkGenericOpenGLRenderWindow Class Reference) no longer exists in the latest version of vtkGener…

---

## [\`vtkExtractSelection()\` removes hidden cells with VTK 9.4](https://discourse.vtk.org/t/vtkextractselection-removes-hidden-cells-with-vtk-9-4/15565)

<div class="topic-metadata">

**Author:** [@keurfonluu](https://discourse.vtk.org/u/keurfonluu)\
**Replies:** 2\
**Last updated:** [July 2, 2025, 2:44pm UTC](https://discourse.vtk.org/t/vtkextractselection-removes-hidden-cells-with-vtk-9-4/15565 "2025-07-02T14:44:30Z")

</div>

Hi, It seems that hidden cells are removed when using vtkExtractSelection() with VTK 9.4. The MRE creates an 8-cell grid, hide cell 0 and 1, then extracts all cells except cell 7, so the output mesh should have 7 cells.…

---

## [vtk volume rendering is not the same with slicer rendering with same classification curve](https://discourse.vtk.org/t/vtk-volume-rendering-is-not-the-same-with-slicer-rendering-with-same-classification-curve/15766)

<div class="topic-metadata">

**Author:** [@Chris\_Young\_Kim](https://discourse.vtk.org/u/Chris_Young_Kim)\
**Replies:** 5\
**Last updated:** [June 28, 2025, 1:23pm UTC](https://discourse.vtk.org/t/vtk-volume-rendering-is-not-the-same-with-slicer-rendering-with-same-classification-curve/15766 "2025-06-28T13:23:29Z")

</div>

I do volume rendering of conebeam CT image using VTK. The result image is different from slicer with the same classification curve. The vtk rendering looks more like CPU Rendering, less shading effect. I use qt6.7 an…

---

## [How to save renderer output (vtk python) in format that is compatible on web side(vtk.js)](https://discourse.vtk.org/t/how-to-save-renderer-output-vtk-python-in-format-that-is-compatible-on-web-side-vtk-js/7482)

<div class="topic-metadata">

**Author:** [@khadija](https://discourse.vtk.org/u/khadija)\
**Replies:** 9\
**Last updated:** [June 27, 2025, 12:03pm UTC](https://discourse.vtk.org/t/how-to-save-renderer-output-vtk-python-in-format-that-is-compatible-on-web-side-vtk-js/7482 "2025-06-27T12:03:49Z")

</div>

i want all the processing on python vtk side and send the resulting file on vtk.js side on webGL that only rendered the results. i want to save renderer output in any file format , that can be used on the other end side…

---

## [Rendering glitches when using vtkSSAOPass and vtkDepthPeelingPass](https://discourse.vtk.org/t/rendering-glitches-when-using-vtkssaopass-and-vtkdepthpeelingpass/15762)

<div class="topic-metadata">

**Author:** [@ctroesch](https://discourse.vtk.org/u/ctroesch)\
**Replies:** 5\
**Last updated:** [June 27, 2025, 11:14am UTC](https://discourse.vtk.org/t/rendering-glitches-when-using-vtkssaopass-and-vtkdepthpeelingpass/15762 "2025-06-27T11:14:29Z")

</div>

I there, I just moved from VTK 9.3.0 to VTK 9.5.0 and I experiment rendering glitches when displaying a scene with vtkSSAOPass on MacOS: I’m on an MacOS 15.4.1 (Sequoia) and using Xcode 16.3 (Apple clang version 1…

---

## [How can I use ray cast volume rendering customizing my own shader?](https://discourse.vtk.org/t/how-can-i-use-ray-cast-volume-rendering-customizing-my-own-shader/15743)

<div class="topic-metadata">

**Author:** [@Eva\_Monclus\_Lahoya](https://discourse.vtk.org/u/Eva_Monclus_Lahoya)\
**Replies:** 4\
**Last updated:** [June 26, 2025, 8:34am UTC](https://discourse.vtk.org/t/how-can-i-use-ray-cast-volume-rendering-customizing-my-own-shader/15743 "2025-06-26T08:34:05Z")

</div>

Hi, I’m working on ray cast volume rendering and would like to customize the rendering process by injecting my own shader code using Shader Replacement at specific stages. So, I tryed to use vtkOpenGLGPUVolumeRayCastMa…

[Previous page](https://discourse.vtk.org/c/support/6.md?page=6)

[Next page](https://discourse.vtk.org/c/support/6.md?page=8)